TRANSMISSION AND WORK MACHINE INCLUDING THE SAME

Technical Field

The present disclosure relates to the field of work machine, in particular relates to a transmission for a work machine.

Background

Work machines such as loaders, excavators, and graders can travel to a desired location for related operations by means of a travelling device (i.e. wheels or tracks) driven by a power source (i.e. engine, electric motor etc.). As the dynamic characteristic of the power source and the load characteristic of the work machine cannot match completely, a transmission needs to be provided between the power source and the travelling device. In addition, the transmission can provide a neutral position to cut off the power connection between the power source and the travelling device even when the power source is in operation.

Transmissions of various types with different configurations are currently known. However, there is not a single type of transmission that can be appliable for all working environments of work machines and power sources. Therefore, depending on the specific type of the power source and the working environment of the work machine, a corresponding transmission that has a simple and reliable structure and is convenient to operate is desired.

Summary

In view of the actual experience and study of the inventors in the field, improved technical solutions are provided herein to achieve the above and/or other technical purposes.

A transmission for a work machine is provided, the transmission comprising: a first shaft; a first fixed gear wheel fixedly installed on the first shaft; a first free gear wheel freely installed on the first shaft; a first clutch configured to be selectively engaged or disengaged to engage or disengage the first free gear wheel with or from the first shaft; a second shaft; a second fixed gear wheel fixedly installed on the second shaft and constantly meshed with the first free gear wheel; a second free gear wheel freely installed on the second shaft and constantly meshed with the first fixed gear wheel; and a second clutch configured to be selectively engaged or disengaged to engage or disengage the second free gear wheel with or from the second shaft.

According to one exemplary configuration, the transmission further comprises a clutch controlling device, which is configured to control the first and second clutches according to operating conditions of the work machine or instructions of an operator of the work machine such that at most one of the two clutches is engaged when the transmission is in operation.

According to one exemplary configuration, a gear ratio between the first fixed gear wheel and the second free gear wheel is set to be different from a gear ratio between the first free gear wheel and the second fixed gear wheel.

According to one exemplary configuration, the transmission further comprises an input shaft configured to receive power input to the transmission, and an input gear wheel fixedly installed on the input shaft and configured to transfer the power to the first shaft.

According to one exemplary configuration, the transmission further comprises a first transmission gear wheel fixedly installed on the first shaft and constantly meshed with the input gear wheel.

According to one exemplary configuration, the transmission further comprises an output shaft configured to output power from the transmission, and an output gear wheel fixedly installed on the output shaft and configured to receive power output from the second shaft. According to one exemplary configuration, the transmission further comprises a second transmission gear wheel fixedly installed on the second shaft and constantly meshed with the output gear wheel.

According to one exemplary configuration, the first clutch and/or the second clutch are configured as a multi-plate clutch or a jaw clutch.

The present disclosure further relates to a work machine, which comprises a power source and a transmission as stated above for receiving power from the power source.

According to one exemplary configuration, the power source comprises an electric motor.

In the present disclosure, as conventionally described in the field, a gear wheel being “fixedly installed” on a shaft means that the gear wheel is connected to the shaft through removable methods such as spline connection, or directly through non-removable methods such as welding, so as to achieve such a transmission connection that the shaft and the gear wheel are rotated synchronously in the same angular speed. In other words, during normal operation of the transmission, rotation of the shaft would necessarily drive the gear wheel into rotation, and vice versa; that is, there is no relative rotation between the shaft and the gear wheel. The connection method opposite to “fixedly installed” is that a gear wheel is “freely installed” on a shaft. That is, the gear wheel is supported on the shaft through e.g. a bearing element and rotatable relative to the shaft, such that when the shaft is in rotation, the gear wheel may not be rotated at the same speed and therefore no power is transferred between the two; or when the gear wheel is in rotation, it cannot drive the shaft into rotation to transfer power.

The gear wheel “freely installed” on the shaft is usually used in cooperation with a “clutch”, which can be selectively engaged or disengaged to engage the gear wheel with the shaft or disengage the gear wheel from the shaft. When the gear wheel is engaged with the shaft, its working state is like the case where the gear wheel is “fixedly installed” on the shaft; and when the gear wheel is disengaged from the shaft, its working state is like the case where the gear wheel is “freely installed” on the shaft. During operation of the transmission, the connection relation between the gear wheel freely installed on the shaft and the shaft is changed by controlling the engagement or disengagement of the clutch, so as to establish or cancel the power transmission relation.

Brief Description of the Drawings

Illustrative embodiments of the present disclosure will be described with reference to the drawings in which: FIG. 1 is a structural diagram of a transmission and its upstream and downstream parts according to one embodiment of the present disclosure.

FIG. 2 is a transmission relation diagram of one gear position of the transmission shown in FIG. 1.

FIG. 3 is a transmission relation diagram of another gear position of the transmission shown in FIG. 1.

Detailed Description

Specific embodiments of the present disclosure will be explained with reference to the drawings.

As shown in FIG. 1, the transmission according to the present disclosure is arranged after the power source and before the travelling device of the work machine. In the illustrated embodiment, the work machine uses an electric motor M as the power source. Besides, the power source may be an internal combustion engine such as a gasoline engine, a diesel engine etc. The travelling device may be wheels 6 schematically shown in FIG. 1. The transmission has a housing 50 in which four gear shafts are arranged e.g. in parallel with one another. The gear shafts are rotatably supported on the housing 50 of the transmission through support elements such as bearings, and different numbers of gear wheels are arranged on the gear shafts as required. It can be seen from FIG. 1 that the uppermost gear shaft is an input shaft 10, which is configured to receive the power input to the transmission. For example, a coupling 4 as shown in FIG. 1 can be used to receive power from the output shaft of the electric motor M. An input gear wheel Z0 is fixedly installed on the input shaft 10. The lowermost gear shaft in FIG. 1 is an output shaft 40, which is configured to output the power with a changed speed from the transmission, e.g. to the wheels 6. A brake 3 may be arranged at a proper position on the transmission chain between the output shaft 40 and the wheel 6. An output gear wheel Z7 is fixedly installed on the output shaft 40. As one of the main improvements of the transmission according to the present disclosure, two intermediate shafts are arranged between the input shaft 10 and the output shaft 40. In order to facilitate depiction, the intermediate shaft in direct transmission connection with the input shaft 10 will be referred to as first shaft 20, and the intermediate shaft in direct transmission connection with the output shaft 40 will be referred to as second shaft 30.

It can be seen from FIG. 1 that three gear wheels Zl, Z2, and Z4 and a first clutch Cl are arranged on the first shaft 20. The gear wheel Zl is fixedly installed on the first shaft 20, and constantly meshed with the input gear wheel Z0 on the input shaft. Therefore, the first shaft 20 can receive input power from the input shaft 10. In the following, the gear wheel Zl will be referred to as “first transmission gear wheel”. One of the gear wheels Z2 and Z4 is fixedly installed on the first shaft 20, and the other is freely installed on the first shaft 20. As explained in the above, the gear wheel freely installed on the first shaft can be engaged with or disengaged from the first shaft through selective engagement or disengagement of the clutch.

More specifically, in the embodiment shown in FIG. 1 , the gear wheel Z2 is freely installed on the first shaft 20 and cooperates with the first clutch Cl, so that the gear wheel Z2 can be engaged with or disengaged from the first shaft through selective engagement or disengagement of the first clutch Cl. The gear wheel Z4 is fixedly installed on the first shaft 20. In the following, the gear wheel Z2 will be referred to as “first free gear wheel”, and the gear wheel Z4 will be referred to as “first fixed gear wheel”. As an alternative arrangement, the gear wheel Z2 may be fixedly installed on the first shaft and the gear wheel Z4 may be freely installed on the first shaft and cooperate with the first clutch C 1.

Similarly, three gear wheels Z6, Z3, and Z5 and a second clutch C2 are arranged on the second shaft 30. The gear wheel Z6 is fixedly installed on the second shaft 30 and constantly meshed with the output gear wheel Z7 on the output shaft 40. Therefore, the second shaft 30 can output power to the output shaft 40. In the following, the gear wheel Z6 will be referred to as “second transmission gear wheel”. One of the gear wheels Z3 and Z5 is fixedly installed on the second shaft 30, and the other is freely installed on the second shaft 30. As explained in the above, the gear wheel freely installed on the second shaft can be engaged with or disengaged from the second shaft through selective engagement or disengagement of the clutch. More specifically, in the embodiment shown in FIG. 1 , the gear wheel

Z5 is freely installed on the second shaft 30 and cooperates with the second clutch C2, so that the gear wheel Z5 can be engaged with or disengaged from the second shaft through selective engagement or disengagement of the second clutch C2. The gear wheel Z3 is fixedly installed to the second shaft 30. In the following, the gear wheel Z5 will be referred to as “second free gear wheel”, and the gear wheel Z3 will be referred to as “second fixed gear wheel”. As an alternative arrangement, the gear wheel Z5 may be fixedly installed on the second shaft and the gear wheel Z3 may be freely installed on the second shaft and cooperate with the second clutch C2.

As the implementation exemplarily shown in FIG. 1, both the clutches Cl and C2 adopt the form of a multi-plate clutch, including a first group of friction plates fixedly installed on the first or second shaft, and a second group of friction plates fixedly installed on an axial projection of the corresponding first or second free gear wheel and capable of selective friction engagement with the first group of friction plates. Further, the multi-plate clutch may be of a hydraulic control type. The working state (engaged or disengaged) of the first clutch Cl can be switched by means of a first control valve VI, and the working state (engaged or disengaged) of the second clutch C2 can be switched by means of a second control valve V2. In the present disclosure, the first and second control valves VI and V2 may be considered as at least a portion of the “clutch controlling device” in the transmission of the present disclosure. Or alternatively, either or both of the first clutch Cl and the second clutch C2 may take the form of a jaw clutch which is well known to a person skilled in the art.

Besides, it can be seen from FIG. 1 that sensors may be arranged in the transmission in order to detect the rotational speed of gear wheels or shafts. For example, a sensor 1 may be arranged to detect the rotational speed of the input gear wheel Z0 on the input shaft, and a sensor 2 may be arranged to detect the rotational speed of the second transmission gear wheel Z6 on the second shaft 30. Naturally, other sensors may be arranged to detect the rotational speed of other gear wheels. For example, another sensor may be arranged to detect the rotational speed of the output gear wheel Z7 on the output shaft.

It is to be noted that FIG. 1 is just a schematic diagram for displaying the connection and transmission relations inside the transmission, rather than a sectional view along a plane. That is, although the four gear shafts are arranged from top to bottom in FIG. 1, it does not mean that they must be located in one plane in the actual structure; instead, they may be positioned respectively in different planes parallel to the drawing plane. In addition, while an input shaft 10 for receiving input power and an output shaft 40 for outputting power are shown in the illustrated embodiment, they are not necessarily provided. Instead, the skilled could conceive that the first shaft 20 is used to directly receive input power of the transmission and/or that the second shaft 30 is used to directly output power having a speed changed by the transmission. Industrial Applicability

A clear and complete explanation has been provided in the above in combination with FIG. 1 concerning the exemplary structure of the transmission and feasible alternative implementations of the present disclosure. The operation method of the transmission will be explained in the following in combination with FIGS. 2 and 3. For the sake of conciseness, only elements related to power transfer in the transmission are shown in FIGS. 2 and 3.

The speed change operation of the transmission according to the present disclosure can be achieved by controlling engagement or disengagement of the first clutch Cl and the second clutch C2 with the clutch controlling device. The clutch controlling device can be configured to automatically control the first and second clutches according to the operating conditions of the work machine such that at most one of them is engaged when the transmission is operating; in this case an automatic transmission is realized. Or alternatively, the clutch controlling device can be configured to perform the above control of the first and second clutches according to instructions of the work machine operator (e.g. a gear shifting instruction indicated by a manual gear shifting operation). As stated in the above, when the first and second clutches are hydraulically controlled multi-plate clutches, the clutch controlling device may include the first and second control valves VI and V2. In FIG. 2, the clutch controlling device performs control such that the first clutch Cl is disengaged (decoupled) and the second clutch C2 is engaged. Therefore, when power from the power source (e.g. the electric motor M) is input through the input shaft 10, the input gear wheel Z0 on the input shaft is rotated along with the input shaft 10, in turn driving the first transmission gearwheel Z1 constantly meshed with the input gear wheel Z0 into rotation, and the first shaft 20 is thus rotated synchronously. As the first clutch Cl is not engaged, the rotational power of the first shaft 20 will not be transferred through the first clutch Cl to the first free gear wheel Z2; instead, it is only transferred directly to the first fixed gear wheel Z4, and in turn to the second free gear wheel Z5 constantly meshed therewith. As the second clutch C2 is engaged, the second free gear wheel Z5 can transfer the power through the second clutch C2 to the second shaft 30, in turn driving the second transmission gear wheel Z6 into rotation, and ultimately driving the output gear wheel Z7 constantly meshed with the gear wheel Z6 and the output shaft 40 into rotation. A person skilled in the art could understand that when the second shaft 30 is rotated, the second fixed gear wheel Z3 fixedly installed on it and the first free gear wheel Z2 constantly meshed with the gear wheel Z3 will be rotated along with the second shaft; however, as the first clutch Cl is disengaged, the rotation of the first free gear wheel Z2 will not influence rotation of the first shaft 20 through the first clutch Cl. A plurality of arrows in FIG. 2 show the power transfer path described above, and the transmission speed ratio or gear position achieved through the power transfer path can be set by designing the gear ratios of meshed gear pairs (Z0/Z1; Z4/Z5; and Z6/Z7) in the power transfer path. According to requirements, the speed ratio of the gear position can be designed to be in the range of 3.5-3.8, serving as a lower gear of the transmission.

In FIG. 3, the clutch controlling device performs control such that the first clutch Cl is engaged and the second clutch C2 is disengaged (decoupled). Therefore, when power from the power source (e.g. the electric motor M) is input through the input shaft 10, the input gear wheel Z0 on the input shaft is rotated along with the input shaft 10, in turn driving the first transmission gear wheel Z 1 constantly meshed with the input gear wheel Z0 into rotation, and the first shaft 20 is thus rotated synchronously. As the first clutch Cl is engaged, the rotational power of the first shaft 20 can be transferred through the first clutch Cl to the first free gear wheel Z2, in turn to the second fixed gear wheel Z3 constantly meshed therewith. As the second fixed gear wheel Z3 is fixedly installed on the second shaft 30, it can transfer power directly to the second shaft 30, in turn driving the second transmission gear wheel Z6 also fixedly installed on the second shaft 30 into rotation, and ultimately driving the output gear wheel Z7 constantly meshed with the gear wheel Z6 and the output shaft 40 into rotation. A person skilled in the art could understand that when the first shaft 20 is rotated, the first fixed gear wheel Z4 fixedly installed on it and the second free gear wheel Z5 constantly meshed with the gear wheel Z4 will be rotated along with the first shaft; however, as the second clutch C2 is disengaged, the rotation of the second free gear wheel Z5 will not influence rotation of the second shaft 30 through the second clutch C2. A plurality of arrows in FIG. 3 show the power transfer path described above, and the transmission speed ratio or gear position achieved through the power transfer path can be set by designing the gear ratios of meshed gear pairs (Z0/Z1; Z2/Z3; and Z6/Z7) in the power transfer path. According to requirements, the speed ratio of the gear position can be designed to be in the range of 1-1.1, serving as a higher gear of the transmission. It can be seen that as long as the gear pair Z4/Z5 is set to have a gear ratio different from that of the gear pair Z2/Z3, the above two gears of the transmission having different speed ratios can be achieved.

A person skilled in the art could easily understand that the transmission will be placed in a neutral position when the clutch controlling device controls both the first clutch Cl and the second clutch C2 to be disengaged (decoupled).

The above only describes the illustrative implementations of spirits and principles of the present disclosure. A person skilled in the art knows that various changes may be made to the described embodiments without deviating from the spirits and principles, and all the changes and their equivalences can be conceived by those skilled in the art and fall within the scope defined by the claims of the present disclosure.