TECHNICAL FIELD

The invention relates to the field of linear motors. One particular example of concern is a linear motor configured for moving an antenna of a base station, or for moving a component of an antenna of a base station. BACKGROUND

In the prior art, motors for antennas are well known. For example, these motors are used for actuating a phase shifter in order to radiate a beam of the antenna at a desired angle of deflection. A transmission system is required in order to transmit the force and the motion of the motor to the phase shifter. In a known design, rigid bars or flexible shafts are used to transmit force/torque to drive the phase shifter to move or rotate the phase shifter. It is also known to functionally connect the motor to a control unit, which manages the power supply strategies and control the movement of the motor. A disadvantage of these prior art devices is that the transmission system requires a long transmission chain, which causes much loss in efficiency and causes that dimension tolerances are accumulated, thereby causing poor transmission precision. In particular in multi-frequency situations, the prior art devices limit the phase shifter layout design. Furthermore, the costs of these driving systems are relatively high.

There is a driving device in the prior art, which on the basis of a ratchet mechanism facilitates a linear movement. This driving device, however, is not very suitable for an antenna or the phase shifter of an antenna, since the driving system provides the linear movement only in one direction. Furthermore, this driving device has a relatively complex layout. SUMMARY

Therefore, it is an objective of the present invention to overcome these disadvantages of the prior art. It is in particular an objective of the present invention to provide a motor, which is compact, more efficient and provides both a forward and a backward movement.

These and other objects, which become apparent upon reading the following description, are solved by the subject-matter of the independent claim. The dependent claims refer to preferred embodiments of the invention.

According to the invention, a linear motor having a forward mode and a backward mode comprises: a reciprocating unit arranged to be moved in a forward direction and in a backward direction, and a thrust unit arranged, in the forward mode, to move in the forward direction in response to the reciprocating unit moving in the forward direction and, in the backward mode, to move in a backward direction opposed to the forward direction in response to the reciprocating unit moving in the backward direction.

Therefore, in each of the forward and backward direction of the thrust unit, the thrust unit can be moved along a desired distance irrespective of the limited distance, which the reciprocating unit can move in its forward and backward direction. That is, the distance the thrust unit can travel is independent of the distance, along which the reciprocating unit moves back and forth, but only dependent on the length of the thrust unit. As such, the reciprocating unit can be accommodated in a relatively small space, and the thrust unit can be selectively moved in the forward or backward direction and along a desired distance being independent of the dimensions of said accommodation space. Furthermore, the reciprocating unit is required to move only linearly. Thus, a relatively compact linear motor is provided. And since the thrust unit moves in response to the reciprocating unit, i.e. the velocity of the thrust unit in the forward and backward direction substantially corresponds to the velocity of the reciprocating unit in the forward and backward direction, respectively, the transmission chain between the thrust unit and the reciprocating unit can be significantly reduced, thereby increasing the efficiency of the linear motor.

In an implementation form of the invention, in the forward mode the thrust unit is arranged to be stationary when the reciprocating unit moves in the backward direction, and in the backward mode the thrust unit is arranged to be stationary when the reciprocating unit moves in the forward direction. It is thus ensured that the thrust unit moves only in the selected direction (forward or backward direction), even though reciprocating unit moves in a reciprocating manner. This effects, in particular, a more accurate movement of the thrust unit.

In a further implementation form of the invention, the linear motor has a blocking mode, and wherein, in the blocking mode, movement of the thrust unit in the forward direction and in the backward direction is blocked. Thereby, additional blocking or braking means are not required to stop the thrust unit from moving.

In a further implementation form of the invention, the linear motor further comprises an actuating device for moving the reciprocating unit in the forward direction and in the backward direction. The actuating device may comprise one or more of the following: a. one or more shape memory alloy (SMA) elements,

b. one or more solenoids,

c. one or more piezoelectric elements, and

d. one or more elastic elements for providing a restoring force depending on a position of the reciprocating unit. These actuating elements can provide a linear motion by extending along a longitudinal axis only, thereby providing a compact layout of the actuating device and the reciprocating unit.

In a further implementation form of the invention, the reciprocating unit is moveable between a first state and a second state, wherein in the first state the reciprocating unit is arranged to mesh with the thrust unit for moving the thrust unit in the forward direction in response to the reciprocating unit moving in the forward direction, thereby operating the linear motor in the forward mode, and wherein in the second state the reciprocating unit is arranged to mesh with the thrust unit for moving the thrust unit in the backward direction in response to the reciprocating unit moving in the backward direction, thereby operating the linear motor in the backward mode. This provides a simple layout of the reciprocating unit for moving the thrust unit, since no further components other than the reciprocating unit are required for transmitting the force and movement of the reciprocating unit to the thrust unit for moving the thrust unit in the desired direction. In a further implementation form of the invention, in the first state the reciprocating unit is arranged to be released from the thrust unit when the reciprocating unit moves in the backward direction, thereby effecting the thrust unit to be stationary when the reciprocating unit moves in the backward direction, and wherein in the second state the reciprocating unit is arranged to be released from the thrust unit when the reciprocating unit moves in the forward direction, thereby effecting the thrust unit to be stationary when the reciprocating unit moves in the forward direction.

In a further implementation form of the invention, the linear motor further comprises a stationary unit for effecting, in the forward mode, that the thrust unit is stationary when the reciprocating unit moves in the backward direction, and for effecting, in the backward mode, that the thrust unit is stationary when the reciprocating unit moves in the forward direction. Thus, both during the backward movement and during the forward movement of the reciprocating unit, the reciprocating unit can remain in direct contact with the thrust unit in order to move the thrust unit only in the forward or the backward direction. This effects an easy control and compact design of the reciprocating unit.

In a further implementation form of the invention, the stationary unit is moveable between a first state and a second state, wherein in the first state the stationary unit is arranged to engage with the thrust unit such that the thrust unit is stationary when the reciprocating unit moves in the backward direction, and wherein in the second state the stationary unit is arranged to engage with the thrust unit such that the thrust unit is stationary when the reciprocating unit moves in the forward direction. This provides a simple layout of the stationary unit for effecting the thrust unit to remain stationary during the backward or forward movement of the reciprocating unit, since no further components other than the stationary unit are required for preventing the thrust unit from moving in the direction being opposite of the desired direction.

In a further implementation form of the invention, the linear motor comprises a switching mechanism for switching at least between the forward mode and the backward mode.

In a further implementation form of the invention, the switching mechanism is arranged to move the reciprocating unit between the first and the second state, thereby switching at least between the forward mode and the backward mode. Therefore, the switching mechanism does not require to directly act on the thrust unit for selectively moving the thrust unit in the forward or backward direction.

In a further implementation form of the invention, the switching mechanism is arranged to elastically deform the reciprocating unit for moving the reciprocating unit between the first and the second state. Therefore, the reciprocating unit can be simply designed, requiring less components; for example, the reciprocating unit can thus be designed monolithic. Furthermore, the restoring force of the elastically deformed reciprocating unit can be used for moving the reciprocating unit in order to engage the reciprocating unit with the thrust unit for the desired movement of the thrust unit, without requiring further components for this movement.

In a further implementation form of the invention, the reciprocating unit comprises one or more first structures, wherein the switching mechanism comprises one or more second structures, wherein the one or more first structures and the one or more second structures are arranged to cooperate with one another in order to move the reciprocating unit between the first and the second state. As such, the structures can easily transform a movement of the switching mechanism in a movement of the reciprocating unit in order to move the reciprocating unit between the first and the second state.

In a further implementation form of the invention, the switching mechanism is arranged to switch the stationary unit between the first state and the second state such that in the forward mode the stationary unit is in its first state for effecting that the thrust unit is stationary when the reciprocating unit moves in the backward direction and such that in the backward mode the stationary unit is in its second state for effecting that the thrust unit is stationary when the reciprocating unit moves in the forward direction. Thus, a simple means for switching the stationary unit between the first state and the second state is provided.

In a further implementation form of the invention, the switching mechanism comprises a switching driving unit arranged to be moved in a forward direction and in a backward direction, wherein the switching mechanism is arranged to switch the linear motor into the forward mode in response to the switching driving unit moving in the forward direction and to switch the linear motor into the backward mode in response to the switching driving unit moving in the backward direction. The switching driving unit may be arranged to move linearly. This provides a compact design for switching the linear motor between the forward mode and the backward mode.

In a further implementation form of the invention, the switching driving unit comprises an actuating device for moving the switching driving unit in the forward direction and in the backward direction. The actuating device may comprise one or more of the following: a. one or more shape memory alloy (SMA) elements,

b. one or more solenoids,

c. one or more piezoelectric elements, and

d. one or more elastic elements for providing a restoring force depending on a position of the switching driving unit. These actuating elements can provide a linear motion by extending along a longitudinal axis only, thereby effecting a compact layout of the actuating device and the switching driving unit.

In a further implementation form of the invention, the reciprocating unit is arranged to move linearly in a first direction, and wherein the switching driving unit is arranged to move linearly in a second direction, wherein the reciprocating unit and the switching driving unit are arranged such that the first direction is substantially parallel to the second direction. Thus, the reciprocating unit and the switching unit can be arranged in a compact manner in the linear motor.

In a further implementation form of the invention, the reciprocating unit can be arranged between the thrust unit and the switching driving unit. Thereby, a compact layout of the linear motor is achieved.

In a further implementation form of the invention, the linear motor is configured for moving an antenna of a base station, or for moving a component of an antenna of a base station. The component may be a phase shifter. Thereby, the linear motor can efficiently move the antenna or the component. Furthermore, the linear motor can be arranged in a compact manner, in particular without the need of a transmission between the linear motor and the antenna or component of the antenna; that is, the linear motor can be directly connected to the antenna or component of the antenna, thereby reducing both losses in efficiency and accumulated dimension tolerances. BRIEF DESCRIPTION OF DRAWINGS

The above described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 schematically shows an embodiment of the linear motor according to the present invention,

FIG. 2 schematically shows a further embodiment of the linear motor or according to the present invention,

FIG. 3 schematically shows the linear motor of FIG. 2 operating in the backward mode, wherein the thrust unit of the linear motor moves in the backward direction in response to the reciprocating unit moving in the backward direction,

FIG. 4 schematically shows the linear motor according to FIG. 2 and 3, wherein the linear motor is operating in the backward mode, and wherein the thrust unit is arranged to be stationary when the reciprocating unit moves in the forward direction,

FIG. 5 schematically shows the linear motor according to FIG. 2 to 4, wherein the reciprocating unit has reached a different position by the movement according to FIG. 4,

FIG. 6 is a schematic cross-sectional view of FIG. 5 along the line VI- VI, FIG. 7 A is a schematic cross-sectional view of the linear motor shown in FIG. 2 to 6 along the line A-A in FIG. 6, with a preferred switching mechanism, wherein the switching mechanism switched the linear motor into the forward mode, FIG. 7B is a detailed view of FIG. 7A,

FIG. 8A is a schematic view of the linear motor shown in FIG. 7A and 7B, wherein the switching mechanism switched the linear motor into the backward mode,

FIG. 8B is a detailed view of FIG. 8A,

FIG. 9A is a schematic view of the linear motor shown in FIG. 7A to 8B, wherein the switching mechanism switched the linear motor into the blocking mode,

FIG. 9B is a detailed view of FIG. 9A,

FIG. 10A is a schematic perspective view of a further embodiment of the linear motor according to the present invention, and

FIG. 10B is a detailed view of FIG. 10A.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 exemplarily shows a linear motor 1 according to an embodiment of the present invention. The linear motor 1 has a forward mode and a backward mode and comprises a reciprocating unit 20, which is arranged to be moved in a forward direction FW (in the figures: to the right) and a backward direction BW (in the figures: to the left). The reciprocating unit 20 is therefore movable between a first point and second point, wherein at the first point the reciprocating unit 20 returns from moving along the backward direction BW to moving along the forward direction FW, and wherein at the second point the reciprocating unit 20 returns from moving along the forward direction FW to moving along the backward direction BW.

The linear motor 1 further comprises a thrust unit 30, which is movable in a forward direction FW and a backward direction BW, which is opposed to the forward direction FW. The forward direction FW of the thrust unit 30 has preferably the same direction as the forward direction FW of the reciprocating unit 20, and the backward direction BW of the thrust unit 30 has preferably the same direction as the backward direction BW of the reciprocating unit 20. The thrust unit 30 is preferably the output of the linear motor 1. Thereby, the thrust unit 30 may be directly or indirectly connected, e.g. by suitable fastening means, to an element which is to be actuated by the linear motor 1. For example, the linear motor 1 is configured for moving an antenna of a base station or for moving a component, e.g. a phase shifter, of an antenna of a base station. As such, the thrust unit 30 may be directly or indirectly connected or connectable to the antenna or the component of the antenna, e.g. the phase shifter.

In the forward mode of the linear motor 1, the thrust unit 30 is arranged to move in the forward direction FW in response to the reciprocating unit 20 moving in the forward direction FW. Thereby, the reciprocating unit 20 moves the thrust unit by a distance in the forward direction FW, wherein said distance equals the distance, which the reciprocating unit 20 moves in the forward direction FW. In the backward mode of the linear motor 1, the thrust unit 30 is arranged to move in the backward direction BW in response to the reciprocating unit 20 moving in the backward direction BW. Thereby, the reciprocating unit 20 moves the thrust unit 30 by a distance in the backward direction BW, wherein said distance equals the distance, which the reciprocating unit 20 moves in the backward direction BW. Given a theoretically infinite long thrust unit 30, the thrust unit 30 can be moved along an infinite distance in the forward direction FW or the backward direction BW by means of the reciprocating unit 20 reciprocating along a limited distance.

It is preferred that in the forward mode of the linear motor 1, the thrust unit 30 is arranged to be stationary when the reciprocating unit 20 moves in the backward direction BW, thereby ensuring that the thrust unit 30 moves only in the forward direction FW in the forward mode. It is also preferred that in the backward mode of the linear motor 1, the thrust unit 30 is arranged to be stationary when the reciprocating unit 20 moves in the forward direction FW, thereby ensuring that the thrust unit 30 moves only in the backward direction BW, when operating the linear motor 1 in the backward mode.

The mechanism for the movement of the thrust unit 30 by means of the reciprocating unit 20 is therefore a ratchet like mechanism, which is configured to move the thrust unit 30 both in the forward direction FW and the backward direction BW. The reciprocating unit 20 may be moveable between a first state and a second state, wherein for the operation of the linear motor 1 in the forward mode, the reciprocating unit 20 is in the first state, and wherein for the operation of the linear motor 1 in the backward mode, the reciprocating unit 20 is in the second state.

The linear motor 1 may comprise a stationary unit 40 for effecting, in the forward mode, that the thrust unit 30 is stationary when the reciprocating unit 20 moves in the backward direction BW, and for effecting, in the backward mode, that the thrust unit 30 is stationary when the reciprocating unit 20 moves in the forward direction FW. This function provided by the stationary unit 40 may be effected by providing the stationary unit 40 to be movable between a first state and a second state. In the first state, the stationary unit 40 is arranged to engage with the thrust unit 30 such that the thrust unit 30 is stationary when the reciprocating unit 20 moves in the backward direction BW. This engagement of the stationary unit 40 with the thrust unit 30 in the first state of the stationary unit 40, however, still facilitates that the thrust unit 30 can be moved in the forward direction FW. In the second state, the stationary unit 40 is arranged to engage with the thrust unit 30 such that the thrust unit 30 is stationary when the reciprocating unit 20 moves in the forward direction FW. This engagement of the stationary and 40 with the thrust unit 30 and the second state of the stationary unit 40, however, still facilitates a thrust unit 30 can be moved in the backward direction BW.

Besides the forward mode and the backward mode, the linear motor 1 may comprise a blocking mode, in which a movement of the thrust unit 30 in the forward direction FW and in the backward direction BW is blocked. This blocking mode may be effected by simultaneously operating the linear motor 1 in the forward mode and in the backward mode, i.e. by complete engagement of the reciprocating unit 20 with the thrust unit 20, thereby effecting that the thrust unit 30 is stationary when the reciprocating unit moves in the forward direction FW and in the backward direction BW, respectively. In this blocking mode, the stationary unit 40 may be both in the first state and the second state, i.e. completely engaged with the thrust unit 30, thereby effecting the thrust unit 30 to be stationary, when the reciprocating unit 20 moves in the backward direction BW and the forward direction FW, respectively. The linear motor 1 may comprise a switching mechanism 50 for switching the linear motor 1 between the forward mode and the backward mode, and preferably also into the blocking mode. For example, the switching mechanism 50 is arranged to move the reciprocating unit 20 and/or the stationary unit 40 for switching the linear motor 1 between the forward mode and the backward mode, and preferably into the blocking mode.

FIG. 2 to 9B show the linear motor 1 in a possible implementation. Same reference signs are used for the same features. A dashed arrow of the backward direction BW or the forward direction FW indicates that the respective component, i.e. the reciprocating unit 20 or the thrust unit 30, does not move in this direction.

The reciprocating unit 20 and/or the thrust unit 30 may be received by or accommodated in a housing 60. The housing 60 may comprise openings 61, through which the thrust unit 30 can move, when the thrust unit 30 is moved in the forward direction FW or the backward direction BW. When viewed in the backward direction BW or the forward direction FW, the openings 61 may have a form, which corresponds to the form of the thrust unit 30. For example, each of the openings 61 is designed as a slit. The thrust unit 30 is preferably designed as a plate.

The thrust unit 30 may connect to the reciprocating unit 20 by way of teeth, which engage with one another. For example, the thrust unit 30 comprises a plurality of teeth 31, which are arranged along the forward direction FW and backward direction BW, respectively. For each of the directions FW and BW of the thrust unit 30, the reciprocating unit 20 may comprise one or more teeth 21. Thus, the reciprocating unit 20 and the thrust unit 30 are meshing with one another in order to move the thrust unit 30 in the forward direction FW and the backward direction BW, respectively. The reciprocating unit 20 is preferably designed as a ratchet structure or plate.

As can be seen in FIG. 7A to 9B, the teeth 21, 31 of the reciprocating unit 20 and the thrust unit 30 may be designed such that a first group 21A, 31A of the teeth 21, 31 can move the thrust unit 30 only in the backward direction BW (FIG. 8A and 8B) and a second group 21B, 31B of the teeth 21, 31 can move the thrust unit 30 only in the forward direction FW (FIG. 7A and 7B). The first group and the second group 21 A, 21B, 31 A, 3 IB of the teeth 21, 31 are preferably provided along a direction - e.g. a width direction of the linear motor 1 - which is perpendicular to the forward direction FW and the backward direction BW, e.g. perpendicular to the drawing plane of each of the FIG. 2 to 5.

FIG. 8A and 8B exemplarily show the linear motor 1 operating in the backward mode. As can be seen in FIG. 8A and 8B, only the teeth of the first group 21A, 31A of the teeth 21, 31 engage with one another, thereby moving the thrust unit 30 only in the backward direction BW in response to the reciprocating unit moving in the backward direction BW. Thus, the reciprocating unit 20 is in its second state, in which the reciprocating unit 20, i.e. the first group 21A of the teeth 21, is arranged to mesh with the thrust unit 30, i.e. the first group 31A of the teeth 31, for moving the thrust unit 30 in the backward direction BW in response to the reciprocating unit 20 moving in the backward direction BW. Consequently, the reciprocating unit 20 moves the thrust unit 30 from the position shown in FIG. 2 in the backward direction BW, via the position shown in FIG. 3 to the position shown in FIG. 4. When the reciprocating unit 20 cannot further move in the backward direction BW, the reciprocating unit 20 returns and moves in the forward direction FW (see FIG. 4). During the movement of the reciprocating unit 20 in the forward direction FW, the thrust unit 30 remains stationary. This is in particular due to the design of the first group 21 A, 31A of the teeth 21, 31, which effects, in particular by a sloped design of the teeth 21, 31, that during the movement of the reciprocating unit 20 in the forward direction FW the first group 21 A of the reciprocating unit 20 is (elastically) pushed away from the thrust unit 30, thereby moving the reciprocating unit 20 relative to the thrust unit 30 in order to engage the first group 21A of the reciprocating unit 20 at a different point of the thrust unit 30 (FIG. 5). At said different point, the reciprocating unit 20 thus can return and move in the backward direction, thereby moving the thrust unit 30 again in the backward direction BW in response to the reciprocating unit again moving in the backward direction BW. This kind of movement substantially corresponds to the mechanism of a ratchet and thus can be arranged in a compact manner.

In the backward mode of the linear motor 1, in which the reciprocating unit 20 is in its second state, the reciprocating unit 20, in particular the teeth of the second group 21B of the teeth 21, may be arranged to be released from the thrust unit 30, i.e. not engaged with the second group 3 IB of the teeth 31, when the reciprocating unit 20 moves in the forward direction FW, thereby effecting the thrust unit 30 to be stationary when the reciprocating unit 20 moves in the forward direction FW. That is, in the backward mode of the linear motor 1 and during the movement of the reciprocating unit 20 in the forward direction FW, the reciprocating unit 20 is in the state as shown in FIG. 8A and 8B, which is the second state of the reciprocating unit 20.

FIG. 7 A and 7B exemplarily show the linear motor 1 operating in the forward mode. As can be seen in FIG. 7A and 7B, only the teeth of the second group 21B, 3 IB of the teeth 21, 31 engage with one another, thereby moving the thrust unit 30 only in the forward direction FW in response to the reciprocating unit 20 moving in the forward direction FW. Thus, the reciprocating unit 20 is in its first state, in which the reciprocating unit 20, i.e. the second group 21B of the teeth 21, is arranged to mesh with the thrust unit 30, i.e. the second group 3 IB of the teeth 31, for moving the thrust unit 30 in the forward direction FW in response to the reciprocating unit 20 moving in the forward direction FW. When the reciprocating unit 20 cannot further move in the forward direction FW, the reciprocating unit 20 returns and moves in the backward direction BW. During the movement of the reciprocating unit 20 in the backward direction BW, the thrust unit 30 remains stationary. This is in particular due to the design of the second group 2 IB, 3 IB of the teeth 21, 31, which effects that during the movement of the reciprocating unit 20 in the backward direction BW the second group 2 IB of the reciprocating unit 20 is (elastically) pushed away from the thrust unit 30, thereby moving the reciprocating unit 20 relative to the thrust unit 30 in order to engage the second group 21B of the reciprocating unit 20 at a different point of the thrust unit 30. At said different point, the reciprocating unit 20 thus can return and move in the forward direction FW, thereby moving the thrust unit 30 again in the forward direction FW in response to the reciprocating unit again moving in the forward direction FW.

In the forward mode of the linear motor 1, in which the reciprocating unit 20 is in its first state, the reciprocating unit 20, in particular the teeth of the first group 21A of the teeth 21, may be arranged to be released from the thrust unit 30, i.e. not engaged with the first group 31A of the teeth 31, when the reciprocating unit 20 moves in the backward direction BW, thereby effecting the thrust unit 30 to be stationary when the reciprocating unit 20 moves in the backward direction BW. That is, in the forward mode of the linear motor 1 and during the movement of the reciprocating unit 20 in the backward direction 20, the reciprocating unit 20 is in the state as shown in FIG. 8A and 8B, which is the first state of the reciprocating unit 20. FIG. 9A and 9B exemplarily show the linear motor 1 operating in the blocking mode. As can be seen in FIG. 9A and 9B, both the teeth of the first group 21 A, 31A and the second group 2 IB, 3 IB of the teeth 21, 31 engage with one another, thereby blocking a movement of the thrust unit 30 in the forward direction FW and in the backward direction BW. This is in particular due to the design of the first group 21 A, 31A and the second group 2 IB, 3 IB of the teeth 21, 31, which effects that a movement of the first group 21 A of the reciprocating unit 20 relative to thrust unit 30 is blocked by the second group 21B of the reciprocating unit 20 meshing with the second group 3 IB of the thrust unit 30, and that a movement of the second group 21B of the reciprocating unit 20 relative to thrust unit 30 is blocked by first group 21 A of the reciprocating unit 20 meshing with the first group 31A of the thrust unit 30. Consequently, the reciprocating unit 20 is in a third state, which effects that the thrust unit 30 is prevented from moving a distance, which is greater than the amplitude of the reciprocating unit 20.

FIG. 2 to 6 exemplarily show a possible implementation of the stationary unit 40. The stationary unit 40 may be stationary provided such that the reciprocating unit 20 and the thrust unit 30 can move relative to the stationary unit 40. For example, the stationary unit 40 is fixed to the housing 60, which accommodates the reciprocating unit 20 and/or the thrust unit 30. In a particularly preferred example, the stationary unit 40 is integrally formed with the housing 60. In other examples, the stationary unit 40 may also be fixed to the housing by one or more fastening elements.

The thrust unit 30 may connect to the stationary unit 40 by way of teeth, which engage with one another. For example, for each of the directions FW and BW of the thrust unit 30, the stationary unit 40 may comprise one or more teeth 41. The teeth 31, 41 may be designed such that a first group 41A the teeth 41 blocks a movement of the thrust unit 30 in the forward direction FW (see FIG. 2 to 5) and a second group 4 IB of the teeth 41 blocks a movement of the thrust unit in the backward direction BW. The first group 41 A and the second group 41B of the teeth 41 are preferably provided along a direction - e.g. a width direction of the linear motor 1 - which is perpendicular to the forward direction FW and the backward direction BW, e.g. perpendicular to the drawing plane of each of the FIG. 2 to 5. In the backward mode of the linear motor 1, which is in particular shown in FIG. 2 to 5, the functioning of the reciprocating unit 20 and the thrust unit 30 in the preferred combination with the stationary unit 40 is preferably as follows. The teeth of the first group 21 A, 31A of the teeth 21, 31 engage with one another, thereby moving the thrust unit 30 only in the backward direction BW in response to the reciprocating unit moving in the backward direction BW. During the movement of the reciprocating unit 20 in the backward direction BW in order to move the thrust unit 30 in the backward direction BW, the stationary unit 40, i.e. the first group 41A of teeth 41, is (elastically) pushed away from the thrust unit 30, thereby moving the thrust unit 30 relative to the stationary unit 40. When the reciprocating unit 20 cannot further move in the backward direction BW, the reciprocating unit 20 returns and moves in the forward direction FW. During the movement of the reciprocating unit 20 in the forward direction FW, the thrust unit 30 remains stationary, in particular due to the design of the first group 41A of the teeth 41 and the engagement with the first group 31A of the teeth, which provides a counter force for preventing the thrust unit 30 to move in the forward direction FW. The reciprocating unit 20, however, moves relative to the thrust unit 30 in order to engage the first group 21A of the reciprocating unit 20 at the different point of the thrust unit 30, wherein at said different point, the reciprocating unit 20 can return and move in the backward direction BW, thereby moving the thrust unit 30 again in the backward direction BW in response to the reciprocating unit again moving in the backward direction BW.

In the backward mode of the linear motor 1, in which the stationary unit 40 is in its second state, the stationary unit 40, in particular the teeth of the second group 41B of the teeth 41, may be arranged to be released from the thrust unit 30, i.e. not engaged with the second group 3 IB of the teeth 31, thereby facilitating that the thrust unit 30 can move in the backward direction BW when the reciprocating unit 20 moves in the backward direction BW.

In the forward mode of the linear motor 1, the functioning of the reciprocating unit 20 and the thrust unit 30 in the preferred combination with the stationary unit 40 is preferably as follows. The teeth of the second group 2 IB, 3 IB of the teeth 21, 31 engage with one another, thereby moving the thrust unit 30 only in the forward direction FW in response to the reciprocating unit 20 moving in the forward direction FW. During the movement of the reciprocating unit 20 in the forward direction FW in order to move the thrust unit 30 in the forward direction FW, the stationary unit 40, i.e. the second group 41B of teeth 41, is (elastically) pushed away from the thrust unit 30, thereby moving the thrust unit 30 relative to the stationary unit 40. When the reciprocating unit 20 cannot further move in the forward direction FW, the reciprocating unit 20 returns and moves in the backward direction BW. During the movement of the reciprocating unit 20 in the backward direction BW, the thrust unit 30 remains stationary, in particular due to the design of the second group 41B of the teeth 41 and the engagement with the second group 3 IB of the teeth 31, which provide a counter force for preventing the thrust unit 30 to move in the backward direction BW. The reciprocating unit 20, however, moves relative to the thrust unit 30 in order to engage the second group 21B of the reciprocating unit 20 at the different point of the thrust unit 30, wherein at said different point, the reciprocating unit 20 can return and move in the forward direction FW, thereby moving the thrust unit 30 again in the forward direction FW in response to the reciprocating unit 20 again moving in the forward direction FW. That is, the teeth 41 have preferably a design, which corresponds to the teeth 31, e.g. a sloped design.

In the backward mode of the linear motor 1, the functioning of the reciprocating unit 20 and the thrust unit 30 in the preferred combination with the stationary unit 40 is preferably as follows. The teeth of the first group 21 A, 31A of the teeth 21, 31 engage with one another, thereby moving the thrust unit 30 only in the backward direction BW in response to the reciprocating unit 20 moving in the backward direction BW. During the movement of the reciprocating unit 20 in the backward direction BW in order to move the thrust unit 30 in the backward direction BW, the stationary unit 40, i.e. the first group 41A of teeth 41, is (elastically) pushed away from the thrust unit 30, thereby moving the thrust unit 30 relative to the stationary unit 40. When the reciprocating unit 20 cannot further move in the backward direction BW, the reciprocating unit 20 returns and moves in the forward direction FW. During the movement of the reciprocating unit 20 in the forward direction FW, the thrust unit 30 remains stationary, in particular due to the design of the first group 41 A of the teeth 41 and the engagement with the first group 31A of the teeth 31, which provide a counter force for preventing the thrust unit 30 to move in the forward direction FW. The reciprocating unit 20, however, moves relative to the thrust unit 30 in order to engage the first group 21 A of the reciprocating unit 20 at the different point of the thrust unit 30, wherein at said different point, the reciprocating unit 20 can return and move in the backward direction BW, thereby moving the thrust unit 30 again in the backward direction BW in response to the reciprocating unit 20 again moving in the backward direction BW.

In the forward mode of the linear motor 1, in which the stationary unit 40 is in its first state, the stationary unit 40, in particular the teeth of the first group 41A of the teeth 41, may be arranged to be released from the thrust unit 30, i.e. not engaged with the first group 31A of the teeth 31, thereby facilitating that the thrust unit 30 can move in the forward direction FW when the reciprocating unit 20 moves in the forward direction FW.

FIG. 2 to 6 and, in particular, FIG. 7A to 9B, exemplarily show a possible implementation of the switching mechanism 50. The switching mechanism 50 is arranged to move the reciprocating unit 20 between the first state and the second state. In order to switch the reciprocating unit 20 between the first state and the second state, the reciprocating unit 20 may be elastically provided, wherein the switching mechanism 50 is arranged to elastically deform or bend the at least partially elastic reciprocating unit 20 for moving the reciprocating unit 20 between the first and the second state. For providing the elasticity of the reciprocating unit 20, the reciprocating unit 20 may comprise a monolithic structure and/or be made of an appropriate material. FIG. 8A and 8B show a state, in which the switching mechanism 50, e.g. a switching element 51, preferably in the form of a rod, elastically deformed the reciprocating unit 20 such that the second group 2 IB of the teeth 21 of the reciprocating unit 20 is (elastically) pushed away from the thrust unit 30 in order to disengage the second group 2 IB from the second group 3 IB of the teeth 31 of the thrust unit 30, whereas the first group 21 A still engages or meshes with the first group 31A of the teeth 31 of the thrust unit 30. The linear motor 1 thus operates in the backward mode. FIG. 7A and 7B show a state, in which the switching mechanism 50, e.g. the switching element 51, elastically deformed the reciprocating unit 20 such that the first group 21 A of the teeth 21 of the reciprocating unit 20 is (elastically) pushed away from the thrust unit 30 in order to disengage the first group 21 A from the first group 31A of the teeth 31 of the thrust unit 30, whereas the second group 21B still engages or meshes with the second group 3 IB of the teeth 31 of the thrust unit 30. The linear motor 1 thus operates in the forward mode.

As can be seen in FIG. 7B, 8B and 9B in more detail, the reciprocating unit 20 may comprise one or more, preferably two, first structures 22A, 22B, and the switching mechanism 50, in particular the switching element 51, may comprise one or more, preferably two, second structures 51 A, 5 IB. The structures 22A, 22B, 51 A, 5 IB are arranged to cooperate with one another in order to move the reciprocating unit 20 between the first and the second state, i.e. to selectively push the first group 21 A or the second group 21B away from the thrust unit 30. For example, each of the one or more first structures 22A, 22B is formed as a protrusion (e.g. a trapezoidal protrusion, a ramp-like protrusion, or a protrusion having an inclined plane), wherein each of the one or more second structures 52A, 52B has a shape corresponding to the first structures 22A, 22B, e.g. having a shape in the form of a recess or notch. Each of the protrusions may be chamfered (e.g. in the form of a trapezoid) in order to facilitate an efficient cooperation with the respectively dedicated recess. In the backward mode, the forward mode and the blocking mode, the structures 22A, 22B, 51 A, 5 IB thus cooperate as follows.

In the backward mode of the linear motor 1, which is shown in FIG. 8A and 8B, the first structure 22A in the form of a protrusion is (fully) accommodated in the second structure 52A in the form of a recess, thereby effecting that the first group 21A of the teeth 21 engages with the first group 31A of the teeth 31, whereas the second structure 22B in the form of a protrusion is only partially accommodated in or even provided outside of the second structure 52B in the form of a recess, thereby effecting that the second group 21B of the teeth 21 is (elastically) pushed away and thus disengaged from the second group 3 IB of the teeth 31.

In the forward mode of the linear motor 1, which is shown in FIG. 7A and 7B, the second structure 22B is (fully) accommodated in the second structure 52B, thereby effecting that the second group 2 IB of the teeth 21 engages with the second group 3 IB of the teeth 31, whereas the first structure 22A is only partially accommodated in or even provided outside of the first structure 52 A, thereby effecting that the first group 21 A of the teeth 21 is (elastically) pushed away and thus disengaged from the first group 31 A of the teeth 31.

In the blocking mode of the linear motor 1, which is shown in FIG. 9 A and 9B, the first structure 22A is (fully) accommodated in the second structure 52A, thereby effecting that the first group 21 A of the teeth 21 engages with the first group 31A of the teeth 31, and the second structure 22B is (fully) accommodated in the second structure 52B, thereby effecting that also the second group 2 IB of the teeth 21 engages with the second group 3 IB of the teeth 31. Additionally or alternatively, the switching mechanism 50 may be arranged to switch the stationary unit 40 between the first state and the second state of the stationary unit 40. In order to switch the stationary unit 40 between the first state and the second state, the stationary unit 40 may be elastically provided, wherein the switching mechanism 50 is arranged to elastically deform the at least partially elastic stationary unit 40 for moving the stationary unit 50 between the first and the second state. For providing the elasticity of the stationary unit 50, the stationary unit 50 may comprise a monolithic structure, e.g. formed from a single piece, wherein the monolithic stationary unit 50 is integrally formed with the housing 60 such that an elastic connection between the stationary unit 50 and the housing 60 is provided. In the backward mode, the switching mechanism 50, e.g. a further switching element 52, preferably in the form of a rod, elastically deforms the stationary unit 40 such that the second group 4 IB of the teeth 41 of the stationary unit 40 is (elastically) pushed away from the thrust unit 30 in order to disengage the second group 41B from the second group 3 IB of the teeth 31 of the thrust unit 30, whereas the first group 41 A still engages with the first group 31A of the teeth 31 of the thrust unit 30. The stationary unit 40 can thus block a movement of the thrust unit 30 in the forward direction and the linear motor 1 thus operates in the backward mode. The switching mechanism 50, e.g. the further switching element 52, may also elastically deform the stationary unit 40 such that the first group 41 A of the teeth 41 is (elastically) pushed away from the thrust unit 30 in order to disengage the first group 41 A from the first group 31A of the teeth 31 of the thrust unit 30, whereas the second group 4 IB still engages with the second group 3 IB of the teeth 31 of the thrust unit 30 in order to block a movement of the thrust unit 30 in the backward direction BW. The linear motor 1 thus operates in the forward mode.

Corresponding to the reciprocating unit 20, the stationary unit 40 may comprise one or more, preferably two, first structures, and the switching mechanism 50, in particular the switching element 52, may comprise one or more, preferably two, third structures. These structures are then arranged to cooperate with one another in order to move the stationary unit 40 between the first and the second state, i.e. to selectively push the first group 41A or the second group 41B away from the thrust unit 30. For example, each of the one or more first structures of the stationary unit 40 is formed as a protrusion (e.g. a trapezoidal protrusion, a ramp-like protrusion, or a protrusion having an inclined plane), wherein each of the one or more third structures of the switching unit 50 has a shape corresponding to the first structures of the stationary unit 40, e.g. having a shape in the form of a recess or notch. Each of the protrusions may be chamfered (e.g. in the form of a trapezoid) in order to facilitate an efficient cooperation with the respectively dedicated recess. In the backward mode, the forward mode and the blocking mode, the first structures of the stationary unit 40 and the one or more third structures of the switching unit 50 thus cooperate as follows.

In the backward mode of the linear motor 1, the first structure of the stationary unit 40 in the form of a protrusion is (fully) accommodated in a third structure of the switching unit 50 in the form of a recess, thereby effecting that the first group 41A of the teeth 41 engages with the first group 31A of the teeth 31, whereas a further first structure of the stationary unit 40 in the form of a protrusion is only partially accommodated in or even provided outside of a further third structure of the switching unit 50 in the form of a recess, thereby effecting that the second group 4 IB of the teeth 41 is (elastically) pushed away and thus disengaged from the second group 3 IB of the teeth 31.

In the forward mode of the linear motor 1, the further first structure of the stationary unit 40 is (fully) accommodated in the further third structure of the switching unit 50, thereby effecting that the second group 4 IB of the teeth 41 engages with the second group 3 IB of the teeth 31, whereas the first structure of the stationary unit 40 is only partially accommodated in or even provided outside of the third structure of the switching unit 50, thereby effecting that the first group 41 A of the teeth 41 is (elastically) pushed away and thus disengaged from the first group 31A of the teeth 31.

In the blocking mode of the linear motor 1, the further first structure of the stationary unit 40 is (fully) accommodated in the further third structure of the switching unit 50, thereby effecting that the second group 4 IB of the teeth 41 engages with the second group 3 IB of the teeth 31, and the first structure of the stationary unit 40 is (fully) accommodated in the third structure of the switching unit 50, thereby effecting that also the first group 41A of the teeth 41 engages with the first group 31A of the teeth 31.

As can be seen in FIG. 2 to 9B, the linear motor 1 may comprise an actuating device 70 for moving the reciprocating unit in the forward direction FW and in the backward direction BW. For example, the actuating device 70 may comprise for each of the forward direction FW and the backward direction BW of the reciprocating unit 20 a respective actuating device element 71, 72. The actuating device 70, preferably each of the actuating device elements 71, 72, may have two ends, wherein one end is fixed with respect to the housing 60, and wherein the other end is fixed to the reciprocating unit 20; alternatively, none of these ends may be fixed to the reciprocating unit 20, e.g. by way of entangling the reciprocating unit 20 by the actuating device or by each of the actuating device elements. As such, a structural change of the dimensions, e.g. of the length, of the actuating device 70 or the actuating device elements 71, 72, e.g. in response to an applied electrical voltage, may be used to move the reciprocating element 20 in the forward direction FW and/or the backward direction BW. The actuating device 70 may comprise one or more of the following: one or more shape memory alloy (SMA) elements, one or more solenoids, one or more piezoelectric elements, and one or more elastic elements for providing a restoring force depending on a position of the reciprocating unit. These actuating device elements 71, 72 may be provided in a longitudinal form, e.g. in the form of a wire.

In a particularly preferred embodiment, each of the actuating device elements 71, 72 comprises a (single) shape memory alloy (SMA) element or wire. In response to a heat applied to the respective shape memory alloy element, e.g. by resistance heating, the shape memory alloy element shortens or shrinks, as soon as a particular temperature is exceeded. More specifically, the resistance heating may be effected by an electrical power source, which heats the shape memory alloy element by resistance heating, wherein at the transformation or transition temperature, the shape memory alloy changes from the martensitic to the austenitic state; thereby the change of the length (shortening) of the element is effected. The shape memory alloy may comprise a nickel titanium alloy and/or nitinol.

Therefore, when the actuating device element 71 in the form of the shape memory alloy element shortens, the reciprocating unit 20 moves in the backward direction BW until the actuating device element 71 reaches its shortest state. In the backward mode, the thrust unit 30 thus simultaneously moves in the backward direction BW. For moving the reciprocating unit 20 in the forward direction FW, the actuating device element 72 in the form of the shape memory alloy element is shortened, and the reciprocating unit 20 moves in the forward direction FW until the actuating device element 72 reaches its shortest state. In the backward mode, the thrust unit 30, however, is not moving in the forward direction. This process of the actuating device elements 71, 72 can be repeated, thereby effecting the reciprocating movement of the reciprocating unit 20. This process is, however, not limited to shape memory alloys, but can be used with any actuating device element, which facilitates a change of the dimension, in particular of the length, in response to a force and/or an electrical voltage and/or current applied to the actuating device element.

The switching mechanism 50 may comprise a switching driving unit 53, which is arranged to be moved in a forward direction, e.g. the forward direction FW, and in a backward direction, e.g. the backward direction BW. The switching mechanism 50 is arranged to switch the linear motor 1 into the forward mode, in particular the reciprocating unit 20 in its second state and/or the stationary unit 40 in its second state, in response to the switching driving unit 53 moving in the forward direction and to switch the linear motor 1 into the backward mode, in particular the reciprocating unit 20 in its first state and/or the stationary unit 50 in its first state, in response to the switching driving unit 53 moving in the backward direction. It is preferred that the switching driving unit 53 is arranged to move linearly.

As can be seen in FIG. 7A, 8A and 9A, the switching mechanism 50 may comprise an actuating device 54 for moving the switching driving unit 50 in the forward direction and in the backward direction. For example, the actuating device 54 may comprise for each of the forward direction and the backward direction of the switching driving unit 50 a respective actuating device element 55, 56. The actuating device 54, preferably each of the actuating device elements 55, 56, may have two ends, wherein one end is fixed with respect to the housing 60, and wherein the other end is fixed to the switching driving unit 50; alternatively, none of these ends may be fixed to the switching driving unit 50, e.g. by way of entangling the switching driving unit 50 by the actuating device or by each of the actuating device elements. As such, a structural change of the dimensions, e.g. of the length, of the actuating device 54 or the actuating device elements 55, 56, e.g. in response to an applied electrical voltage, may be used to move the switching driving unit 50 in the forward direction and/or the backward direction. The actuating device 54 may comprise one or more of the following: one or more shape memory alloy (SMA) elements, one or more solenoids, one or more piezoelectric elements, and one or more elastic elements for providing a restoring force depending on a position of the reciprocating unit. These actuating device elements 55, 56 may be provided in a longitudinal form, e.g. in the form of a wire. In a particularly preferred embodiment, each of the actuating device elements 55, 56 comprises a (single) shape memory alloy (SMA) element or wire, as described above with respect to the actuating device elements 71, 72. Therefore, when the actuating device element 55 in the form of the shape memory alloy element shortens, the switching driving unit 50 moves in the backward direction BW, e.g. until the actuating device element 55 reaches its shortest state. According to this movement, e.g. in the forward mode, linear motor 1 thus switches into the backward mode. For subsequent switching of the linear motor 1 into the forward mode, the actuating device element 56 in the form of the shape memory alloy element is shortened, and the switching driving unit 50 thus moves in the forward direction, e.g. until the actuating device element 72 reaches its shortest state. This process of shortening the actuating device elements 55, 56 is, however, not limited to shape memory alloys, but can be used with any actuating device element, which facilitates a change of the dimension, in particular of the length, in response to a force and/or an electrical voltage and/or current applied to the actuating device element.

The switching driving unit 53 may comprise a switching driving unit structure 57, to which the actuating device 54, in particular one end of each of the actuating device elements 55, 56, is directly connected. The switching driving unit structure 57, e.g. in the form of a plate, may move the switching element 51 (for switching the reciprocating unit 20 between its first state and second state) and/or the switching element 52 (for switching the stationary unit 40 between its first state and second state) directly or indirectly. An indirect movement of the switching element 51 and/or the switching element 52 by means of the switching driving unit structure 57 may be effected by a transmission 58 between the switching driving unit structure 57 on the one side and the switching element 51 and/or the switching element 52 on the other side. The transmission 58 is configured to transmit a motion of the switching driving unit structure 57 to the switching element 51 and/or the switching element 52, such that the switching element 51 and/or the switching element 52 can accordingly switch the reciprocating unit 20 and/or the stationary unit 50 between their respective first and second state, i.e. cooperate with the respective structures of the switching element 51 and/or the switching element 52 in order to switch between their first and second state. For example, the transmission 58 is configured to translate a linear motion of the switching driving unit structure 57, which is directed in a first direction, into a linear motion of the switching element 51 and/or the switching element 52, which is directed in a second direction; said first direction may be directed in the forward direction FW or backward direction BW, wherein the second direction is not directed in the forward direction FW or backward direction BW, but encloses an angle with the forward direction FW or backward direction BW, e.g. substantially 90°.

As shown in FIG. 7A, 8A, 9A and, in particular, in FIG. 10A and 10B, for each of the switching elements 51, 52, the transmission 58 may comprise a respective transmission element 58A, 58B. The respective transmission element 58A, 58B, e.g. designed as a rod, may be rotatable about a rotation axis in order to translate the linear motion of the switching driving unit structure 57 into the linear motion of the switching element 51 and 52, respectively. For example, each of the transmission elements 58 A, 58B may comprise a first lever on the side of the switching driving unit structure 57 and a second lever on the side of the respective switching element 51, 52. The first lever and the second lever may be provided such that the linear motion of the switching driving unit structure 57 in the first direction rotates the first lever and thus the transmission element 58 A, 58B about the rotation axis, wherein this rotation in turn rotates the second lever, thereby moving the respective switching element 51, 52 in the second direction. As can be seen in FIG. 10B, the levers of the respective transmission element 58A, 58B may be provided at different angles with respect to and around the rotation axis. More specifically, when viewed in the direction of the rotation axis, the first lever and the second lever may enclose an angle, e.g. substantially 90°. Each lever may comprise a respective protrusion, which is rotatably received in a corresponding recess of the switching driving unit structure 57 and the switching element 51, 52, respectively, so that the first lever can rotate with respect to the switching driving unit structure 57 and the second lever can rotate with respect to the respective switching element 51, 52.

In a preferred example, the reciprocating unit 20 is arranged to move linearly in a first direction, and the switching driving unit 50 is arranged to move linearly in a second direction, wherein the reciprocating unit 20 and the switching driving unit 50 are arranged such that the first direction is substantially parallel to the second direction. In particular, the first direction lies in a first plane and the second direction lies in a second plane, wherein the first plane and the second plane are parallel to one another. For a particularly compact layout of the linear motor 1, the reciprocating unit 20 may be provided or sandwiched between the thrust unit 30 and the switching driving unit 50. The linear motor 1 may comprise a (electronic) control unit for controlling the reciprocating unit 20 and/or the switching mechanism 50, in particular the switching driving unit 53. For example, the control unit may provide the actuating device 70 with a periodic signal in order to effect the actuation of the reciprocating unit 20. The periodic signal may have a defined frequency, so that on the basis of the defined frequency of the periodic signal the frequency of the periodic movement of the reciprocating unit 20 can be adjusted. Thus, the higher the frequency of the periodic signal is set, the faster the thrust unit 30 can move in the respective direction. The control unit may provide the switching driving unit 53 with at least two signals, wherein a first signal is used for switching the linear motor 1 into the forward mode, and wherein a second signal is used for switching the linear motor 1 into the backward mode. The control unit may comprise an interface, which is configured to be functionally connected to a functional unit so that the functional unit can input control parameters into the control unit for controlling the reciprocating unit 20 and/or the switching mechanism 50. The functional unit may be a user-interface or may be functionally connected to a user-interface.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word“comprising” does not exclude other elements or steps and the indefinite article“a” or“an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.