Field of the invention

The present invention relates to a tubular actuator, comprising a motor, preferably a cylindrical motor, wherein the motor is disposed in an elongated motor housing, preferably a cylindrical motor housing, wherein the tubular actuator has an inner position and an outer position. Background of the invention

In wheel chairs, actuators are often used for adjusting different features such as seat height, etc. In such applications, it is a problem if the actuators become too large. The shortest length of the actuator, the installation length, is often important for designing the wheel chairs in an optimal and compact manner.

Object of the invention

The object of the invention is to indicate a compact actuator having as short an installation length as possible. Description of the invention

According to the invention, this is achieved by means of a tubular actuator of the type mentioned by way of introduction, which is characterized in that the tubular actuator comprises a threaded tube with a thread, preferably a cylindrical threaded tube, wherein the threaded tube has a length that at least corresponds to the length of the motor housing, wherein the threaded tube is disposed such that the threaded tube, at least in the inner position, substantially encloses the motor housing, wherein the tubular actuator further comprises an engagement member, wherein the engagement member comprises means for engaging the threaded tube, wherein the engagement member and the threaded tube are movable relative to each other.

The inner position and outer position of the tubular actuator are defined by the movability of the threaded tube and the engagement member relative to each other. The distance between the inner position and the outer position defines the travel length of the actuator. The threaded tube comprises a thread, typically along the entire length of the threaded tube. The engagement member comprises means, for example in the form of a simple pin, tap or the like, capable of engaging the thread of the threaded tube. Accordingly, either the threaded tube or the engagement member will move relative to each other, if one of the parts is rotated by the motor. Typically, the inner position will be when the engagement member is located at one end of the threaded tube, and thus the outer position will be when the engagement member is located at the other end of the threaded tube.

Provided that the threaded tube has the same length as the motor housing, the travel length will be defined by the length of the motor housing in that the threaded tube, at least in the inner position, encloses the motor housing. Hereby, an actuator is achieved which, in its most compact form, has a travel length that is of the same length as the motor and thereby the motor housing, at the same time as also the installation length is defined by the length of the motor housing. If a longer travel length is desired, the threaded tube can be made longer relative to the motor housing. That is to say, the size of the actuator can be defined as the desired travel length, however, limited by the size of the motor. This provides very compact and versatile actuators.

According to a further embodiment, the tubular actuator is characterized in that the thread of the threaded tube is disposed on the outside of the threaded tube, and wherein the threaded tube is connected to the motor such that the threaded tube is rotatable relative to the motor housing.

In this embodiment, the threaded tube is disposed around the motor housing such that the thread is on the outside of the threaded tube. The threaded tube is connected to the motor, typically via the motor axle, such that the threaded tube can rotate when the motor is activated.

When the threaded tube rotates, the engagement member will be moved along the threaded tube due to the engagement with the thread. The tubular actuator can also comprise one or several bearings, around which the threaded tube can rotate, in order to minimize wear, noise, etc.

According to a further embodiment, the tubular actuator is characterized in that the engagement means comprises a forward attachment for attachment to a movable part.

The engagement member can be attached to a movable part in that the engagement member comprises a forward attachment. Hereby, the movable part can be moved by the engagement member, when the engagement member is moved by rotating the threaded tube. The forward attachment can be a threaded hole for receiving a bolt, screw or the like, or other suitable forms of attachment means. According to a further embodiment, the tubular actuator is characterized in that the thread of the threaded tube is disposed on the inside of the threaded tube, and wherein the engagement member is connected to the motor such that the engagement member is rotatable relative to the motor housing. In this embodiment, the engagement member is connected to the motor, typically via the motor axle, such that the engagement member can rotate. The threaded tube is disposed around the motor housing, with the thread on the inside, such that the threaded tube will move relative to the engagement member and thereby the motor housing when the engagement member is rotated. In the inner position, the threaded tube will substantially enclose the entire motor housing. When the motor is activated, the threaded tube will be moved toward the outer position and thus away from the motor housing.

According to a further embodiment, the tubular actuator is characterized in that the threaded tube comprises a forward attachment on the outside for attachment to a movable part.

The forward attachment can be disposed at any position along the entire length of the threaded tube. This offers a large number of possibilities to be able to adapt the tubular actuator to different applications.

Furthermore, the threaded tube could comprise a plurality of forward attachments, so that a single tubular actuator can be used in a large number of different applications just by using different forward attachments. According to a further embodiment, the tubular actuator is characterized in that the motor housing is connected to a rearward attachment for attachment to a fixed mechanical part.

The motor housing can be attached to a fixed mechanical part in that it is connected to a rearward attachment, so that the motor housing cannot rotate, and so that the tubular actuator is securely attached. According to a further embodiment, the tubular actuator is characterized in that the engagement member is a nut, wherein the nut comprises a thread corresponding to the thread on the threaded tube. A strong connection to the thread of the threaded tube is achieved in that the engagement member is a nut, and therefore a large torque can be produced, when either the nut or the threaded tube is rotated. The thread on the nut can either be formed on the inside such that the nut can be screwed onto a threaded tube, or the thread can be on the outside such that the nut can be screwed into a threaded tube.

According to a further embodiment, the tubular actuator is characterized in that the motor is an electric motor.

Electric motors are preferred in many situations, for example in wheel chairs, since electricity is often already available. Furthermore, electric motors have the advantage that they are inexpensive and are available in small compact sizes.

However, the tubular actuator is not limited to use in connection with an electric motor. Hydraulic, pneumatic or other forms of motors can also be used.

Description of drawings

In the following, the invention will be described more closely with reference to the accompanying drawings, in which Fig. 1 shows an exploded view of the tubular actuator, with external thread,

Fig. 2 shows the tubular actuator with external thread,

Fig. 3 shows an exploded view of the tubular actuator with internal thread,

Fig. 4 shows the tubular actuator with internal thread. In the description of the figures, identical or corresponding elements will be designated by the same reference numeral in the different figures. Thus, an explanation of all details in connection with each individual figure/embodiment will not be given.

Detailed description of the invention

Figure 1 shows an exploded view of the tubular actuator 1. In the shown embodiment, the tubular actuator comprises a threaded tube 2, wherein the thread 3 is disposed on the outside of the threaded tube 2. A nut 4 is disposed on the threaded tube 2. The nut 4 comprises a forward attachment 5. The tubular actuator 1 also comprises a motor housing 6, wherein the motor housing is connected to a rearward attachment 7. A motor 8 is placed in the motor housing 6, and the motor housing 6 is closed by an end part 9. A bearing 10 is disposed between the end part 9 and the threaded tube 2. The threaded tube 2 is connected to the motor axle 1 1, via a bottom part 12, wherein the bottom part 12 comprises a slit 13 for receiving the motor axle 11. The motor housing 6 also comprises an additional bearing 14, for supporting the threaded tube 2.

Figure 2 shows the tubular actuator 1 of Figure 1 in an assembled condition. When the motor axle 1 1 rotates 2, the threaded tube 2 will rotate, and the nut 4 will move along the thread 3.

Figure 3 shows an exploded view of another embodiment of the tubular actuator 1. In this embodiment, the tubular actuator 1 comprises a threaded tube 15 with an internal thread (not visible). A nut 16 is connected to the motor axle 1 1 via a bearing 17. The nut 16 is screwed into the threaded tube 15 via the thread (not visible) of the nut. The threaded tube 15 further comprises a forward attachment 18.

Figure 4 shows the tubular actuator 1 of figure 3 in an assembled condition. When the motor axle 1 1 rotates, the nut 16 will rotate, and thereby displace the threaded tube 15 relative to the motor housing 6.