CN116221396A

CN116221396A - Transfer case

Info

Publication number: CN116221396A
Application number: CN202111468593.0A
Authority: CN
Inventors: 郑飞翔; 徐志力; 吴少雄
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Holding China Co Ltd
Priority date: 2021-12-03
Filing date: 2021-12-03
Publication date: 2023-06-06

Abstract

The invention relates to a transfer case. The transfer case comprises a clutch separating mechanism and a gear shifting mechanism, wherein the gear shifting mechanism comprises a shifting fork. Wherein the shift mechanism further comprises a first hydraulic actuator for driving the fork and a first hydraulic line for supplying hydraulic fluid to the first hydraulic actuator. The transfer case is simple in structure.

Description

Transfer case

Technical Field

The invention relates to the technical field of vehicles. In particular, the invention relates to a transfer case for a drive train of a motor vehicle.

Background

In a multi-axle motor vehicle, a transfer case is provided for distributing the power output by the engine to a plurality of different drive axles. The transfer case is typically arranged at the rear end in the torque output direction of the transmission. The transfer case transmits power from the engine to the front axle and the rear axle of the vehicle, respectively.

Current conventional transfer case designs are seen in the CN 113586696A et al patent literature. Such transfer cases include a mechanical fork for shifting gears. The fork is axially movable between positions corresponding to different gears. The clutch release mechanism for controlling the clutch may push against the clutch when the fork is in different gear, thereby switching the clutch between the engaged state and the released state. The actuator of the clutch release mechanism includes a rotatable cam plate having a plurality of grooves formed therein. Due to the different depths of the grooves on the cam plate, the cam plate also moves axially during rotation. The clutch and the actuator will be engaged or disengaged depending on the direction of rotation of the cam plate.

In current designs, the actuators are typically all-metal in construction, heavy in weight, and complex in construction and assembly processes. Meanwhile, a motor for driving the actuator has a high cost. Further, a shock phenomenon occurs when the actuator and the clutch are shifted from the disengaged state to the engaged state. In addition, after wear of the friction plate group of the clutch, the stroke of the actuator needs to be adjusted to maintain its original function.

Disclosure of Invention

The object of the present invention is therefore to provide an improved transfer case.

The above-mentioned technical problem is solved by a transfer case according to the invention. The transfer case comprises a clutch separating mechanism and a gear shifting mechanism, wherein the gear shifting mechanism comprises a shifting fork. Wherein the shift mechanism further comprises a first hydraulic actuator for driving the fork and a first hydraulic line for supplying hydraulic fluid to the first hydraulic actuator. The construction of the hydraulic actuator is simpler than that of existing mechanical actuators. Furthermore, the hydraulic actuator does not require a dedicated motor that is bulky and costly to drive, but rather only requires hydraulic lines to provide hydraulic fluid to drive. Therefore, the arrangement space in the transfer case can be effectively saved.

According to a preferred embodiment of the invention, the first hydraulic line may be adapted to be connected to the transmission for introducing hydraulic fluid from the transmission to the first hydraulic actuator. Because of the lack of a hydraulic source in the transfer case, the hydraulic lines introduce hydraulic fluid from a transmission with a sufficient hydraulic source, which not only solves the problem of hydraulic fluid supply, but also does not require additional space inside the transfer case.

According to another preferred embodiment of the present invention, the first hydraulic actuator may include a first housing and a first piston, the first housing may include a first cavity extending in an axial direction, and the first piston is axially movably mounted in the first cavity. A working chamber may be defined between the piston and the end of the cavity for containing hydraulic fluid, the hydraulic fluid in the working chamber being capable of generating an axial hydraulic thrust force on the piston to control movement of the piston along the cavity.

According to another preferred embodiment of the invention, at least a portion of the fork may be connected to the first piston through the first housing, and the at least a portion of the fork may be axially slidable with respect to the first housing following the first piston.

According to another preferred embodiment of the present invention, the shift mechanism may further include a guide rod extending through the shift fork in an axial direction, the guide rod being capable of guiding the shift fork to move in the axial direction, and the first housing may be fixedly connected to the guide rod. The guide rod is an existing part for guiding the shifting fork to move in the gear shifting mechanism, and the first shell is fixed by the guide rod, so that the installation mode of the hydraulic actuator can be simplified.

According to another preferred embodiment of the invention, the first piston is movable in an axially central region of the first cavity, so that two hydraulic chambers are defined in the first cavity, one at each axial end of the first piston. By cooperatively controlling the hydraulic fluid in the two hydraulic chambers, the first piston can be stably driven to move along the first cavity.

According to another preferred embodiment of the invention, the first housing comprises two hydraulic ports communicating with the two hydraulic chambers, respectively, the two hydraulic ports being connected to the first hydraulic line, respectively. The flow of fluid from the first hydraulic line to the two hydraulic ports can be controlled by a solenoid valve of simple construction.

According to another preferred embodiment of the present invention, the clutch release mechanism may comprise a second hydraulic actuator for driving the clutch and a second hydraulic line for supplying hydraulic fluid to the second hydraulic actuator. This also results in an effective saving of space in the transfer case due to the elimination of the motor.

According to another preferred embodiment of the invention, the second hydraulic line may be adapted to be connected to the transmission for introducing hydraulic fluid from the transmission to the second hydraulic actuator. This also solves the problem of hydraulic fluid supply and does not require additional space inside the transfer case.

According to another preferred embodiment of the present invention, the second hydraulic actuator may comprise a second housing comprising an axially extending second cavity in which the second piston is axially movably mounted, the second cavity comprising axially opposite closed and open ends, a second piston and a release bearing mounted at the end of the second piston facing the open end. A working chamber is defined between the second piston and the closed end of the second cavity for containing hydraulic fluid, the hydraulic fluid in the working chamber being capable of generating an axial hydraulic thrust force on the second piston to control movement of the second piston along the second cavity. The second piston may abut the clutch of the transfer case through a release bearing, thereby allowing the clutch to rotate relative to the second piston while providing axial thrust to the clutch.

Drawings

The invention is further described below with reference to the accompanying drawings. Like reference numerals in the drawings denote functionally identical elements. Wherein:

FIG. 1 illustrates a schematic diagram of a transfer case according to an exemplary embodiment of the present invention;

fig. 2a and 2b show a perspective view and a cross-sectional view, respectively, of a shift mechanism of a transfer case according to an exemplary embodiment of the invention; and

fig. 3a and 3b show a perspective view and a cross-sectional view, respectively, of a second hydraulic actuator of a transfer case according to an exemplary embodiment of the invention.

Detailed Description

Specific embodiments of transfer cases according to the present invention will be described below with reference to the accompanying drawings. The following detailed description and the accompanying drawings are provided to illustrate the principles of the invention and not to limit the invention to the preferred embodiments described, the scope of which is defined by the claims.

According to an embodiment of the present invention, a transfer case is provided. Such transfer cases are installed in the drive trains of motor vehicles and are typically arranged at the rear end of the transmission (relative to the engine) for distributing the power output by the engine to a plurality of different drive axles.

Fig. 1 shows a schematic view of a transfer case according to an exemplary embodiment of the invention. As shown in fig. 1, the transfer case includes a shift mechanism, a clutch release mechanism, a clutch 10, a propeller shaft 20, and the like. The clutch 10 is shown schematically as a friction clutch having a friction plate set that is movable in an axial direction. The clutch 10 is formed in a generally annular configuration with the drive shaft 20 passing substantially coaxially through the clutch 10.

The shift mechanism includes a shift fork 30, a first hydraulic actuator 50, and a first hydraulic line (not shown). As shown in fig. 1, the first hydraulic actuator 50 is disposed substantially in parallel on one side of the drive shaft 20. The shift fork 30 extends between the first hydraulic actuator 50 and the drive shaft 20.

Fig. 2a and 2b show a perspective view and a cross-sectional view, respectively, of the gear shifting mechanism. As shown, the first hydraulic actuator 50 includes a first housing 51 and a first piston 52. The first housing 51 is formed in a substantially cylindrical shape and has a cylindrical inner cavity extending in the axial direction, which may be referred to as a first cavity. The axial direction of the first housing 51 and the first cavity is substantially parallel to the drive shaft 20.

The first piston 52 is mounted in the first cavity and is axially movable along the first cavity. The first piston 52 conforms to the cross-sectional shape of the first cavity such that the first piston 52 can contact the side walls of the first cavity, thereby sealing off the spaces located on both axial sides of the first piston 52. The first piston 52 moves in an axially middle region of the first cavity and thereby defines two hydraulic chambers, i.e., a first hydraulic chamber 511 and a second hydraulic chamber 512, respectively, at both axial ends of the first piston 52. Each hydraulic chamber is located between a respective end of the first housing 51 and the first piston 52. The end of the first housing 51 may be closed by a detachable member to facilitate the installation of the first piston 52.

The first housing 51 is also formed with two hydraulic ports, namely a first hydraulic port 513 and a second hydraulic port 514. Wherein the first hydraulic port 513 communicates with the first hydraulic chamber 511 and the second hydraulic port 514 communicates with the second hydraulic chamber 512. Each hydraulic port penetrates a side wall of the first housing 51, respectively. Preferably, two hydraulic ports are respectively communicated to opposite ends of the side wall of the first cavity so that the two hydraulic ports can always communicate with the corresponding hydraulic chambers regardless of the axial position of the first piston 52.

A first hydraulic line (not shown) is arranged outside the first hydraulic actuator 50 and is connected to the transmission of the motor vehicle in order to introduce hydraulic fluid from the transmission to the first hydraulic actuator 50. There are typically many hydraulically actuated components and corresponding hydraulic sources in the transmission (not shown) so that sufficient hydraulic fluid may be provided to the first hydraulic actuator 50 in the transfer case. In particular, the first hydraulic line may be of various suitable hose or conduit configurations, as the invention is not limited in this regard. The first hydraulic line has an input connected to a hydraulic source in the transmission and an output connected to the first housing 51 and communicating with two hydraulic ports on the first housing 51, respectively. The hydraulic source in the transmission may be, for example, a hydraulic main pump of the transmission. Hydraulic fluid from the transmission may flow to the first housing 51 via the first hydraulic line and into the respective hydraulic chambers via the hydraulic ports. A hydraulic valve (not shown) may be disposed in the first hydraulic line or hydraulic port to control the flow state of the hydraulic fluid, including controlling the on-off and/or flow rate of the flow path.

The first hydraulic chamber 511 and the second hydraulic chamber 512 may contain hydraulic fluid introduced into the hydraulic chambers from the respective hydraulic ports, and generate hydraulic pressure in the axial direction to the first piston 52, thereby controlling the first piston 52 to move in the axial direction. Preferably, in order to prevent leakage of hydraulic fluid, a sealing ring may be provided between the first piston 52 and the side wall of the first cavity.

An opening 515 toward the fork 30 is formed in a region of an axial middle portion of the first housing 51. A portion of the end of the fork 30 extends into the opening 515 and is fixedly coupled with the first piston 52. The first piston 52 may thereby push the fork 30 together to move axially. The shift fork 30 moving in the axial direction can perform a shift function. The axial movement range of the first piston 52 is limited by the opening 515 and the fork 30. Throughout the movable range of the first piston 52, the opening 515 is always closed by the first piston 52 without communicating with any of the hydraulic chambers.

To guide the axial movement of the fork 30, the shift mechanism may further include a guide bar 40. The guide rod 40 extends substantially parallel to the transmission shaft 20 and the first housing 51, and axially passes through the fork 30. The guide rod 40 thus guides the shift fork 30 to move in the axial direction. In addition, the guide bar 40 may be provided with a positioning feature to position the axial position of the fork 30. The first housing 51 and the guide bar 40 may be fixedly coupled together by one or more coupling portions 53. This allows the first hydraulic actuator 50 to be positioned by the guide rod 40. For example, one connection portion 53 may be provided at each end of the first housing 51, each connection portion 53 extending perpendicularly to the axial direction between the guide bar 40 and the first housing 51.

Fig. 3a and 3b show a perspective view and a cross-sectional view, respectively, of a clutch release mechanism of a transfer case according to an exemplary embodiment of the invention. The clutch release mechanism may preferably include a second hydraulic actuator 60 and a second hydraulic line (not shown). As shown in fig. 1, the second hydraulic actuator 60 is formed in a substantially annular structure. The drive shaft 20 passes substantially coaxially through the second hydraulic actuator 60. The second hydraulic actuator 60 is disposed axially adjacent to the clutch 10.

As shown in fig. 3b, the second hydraulic actuator 60 may include a second housing 61, a second piston 62, and a release bearing 63. The second housing 61 is formed in an annular structure arranged substantially coaxially with the drive shaft 20. The second housing 61 includes a second cavity extending substantially axially. The second cavity includes axially opposite open and closed ends. The second cavity is also an annular structure arranged substantially coaxially with the second housing 61. Wherein the open end of the second cavity faces the clutch 10 when the second hydraulic actuator 60 is mounted on the drive shaft 20. The second housing 61 is also formed with a hydraulic passage 611. The hydraulic passage 611 extends in the second housing 61, and has one end communicating to the outer surface of the second housing 61 and the other end communicating to the second cavity.

Similar to the first hydraulic line, the second hydraulic line is arranged outside the second hydraulic actuator 60 and is connected to the transmission of the motor vehicle in order to introduce hydraulic fluid from the transmission to the second hydraulic actuator 60. One end of the second hydraulic line is connected to a hydraulic pressure source in the transmission, and the other end is connected to the second housing 61 and communicates with the hydraulic passage 611 on the second housing 61. The hydraulic source in the transmission may likewise be the hydraulic main pump of the transmission. Hydraulic fluid from the transmission may flow to the second housing 61 via the second hydraulic line and into the second cavity of the second housing 61 via the hydraulic channel 611. A hydraulic valve (not shown) may also be arranged in the second hydraulic line or hydraulic channel 611 to control the flow state of the hydraulic fluid.

The second piston 62 is also formed in an annular structure coaxially arranged with the second cavity. The second piston 62 may be inserted axially into the second cavity from the open end of the second cavity. The second piston 62 conforms to the cross-sectional shape of the second cavity such that the second piston 62 is axially movable within the second cavity and is capable of contacting both the outer and inner side walls of the second cavity to seal the interior of the second cavity from the external environment. Thus, a working chamber 612 of the second hydraulic actuator 60 is defined between the second piston 62 and the closed end of the second cavity. The working chamber 612 may contain hydraulic fluid introduced from the hydraulic passage 611 into the second cavity and generate hydraulic pressure in the axial direction to the second piston 62, thereby controlling the second piston 62 to move in the axial direction.

In a preferred embodiment, to ensure that the second piston 62 does not block the hydraulic passage 611 in any axial position, the second hydraulic passage 611 may be in communication with the closed end of the second cavity. This allows the opening of the second hydraulic passage 611 to communicate with the working chamber 612 at all times.

A release bearing 63 is mounted at the end of the second piston 62 facing the open end. The release bearing 63 may be, for example, an annular thrust bearing. The release bearing 63 is arranged substantially coaxially with the second piston 62 and axially abuts between the clutch 10 and the second piston 62. When the second piston 62 moves axially in the second cavity, the second piston 62 can push the clutch 10 via the release bearing 63, thereby controlling the clutch 10 to switch between the engaged state and the released state.

The radial dimensions of the clutch 10, the release bearing 63 and the second piston 62 are substantially the same, ensuring that the three can abut each other in the axial direction. Since the radial dimension of the clutch 10 is typically much larger than the dimension of the drive shaft 20, the radial dimension of the entire second hydraulic actuator 60 may also be much larger than the dimension of the drive shaft 20. This allows a large empty space between the second hydraulic actuator 60 and the drive shaft 20. In addition, since the motor is not required to control the clutch, the arrangement space inside the transfer case can be saved. These empty spaces can be used, for example, for lubricating pumps or the like in which transfer cases are arranged.

The transfer case according to the invention uses two sets of hydraulic actuators instead of the conventional mechanical actuators, so that the motors for driving the actuators are omitted, which saves not only layout space but also production costs. With reduced components, the axial dimensions of the transfer case can be reduced, so that a more compact layout is achieved. Meanwhile, the release bearing can be always abutted between the clutch and the piston, so that the problems of impact and vibration are avoided, and the release bearing serving as the thrust bearing can compensate the misalignment between the parts at two sides in the axial direction, so that the requirement on the installation precision is reduced. In addition, the hydraulic actuator has an automatic stroke compensation function, and when the friction plate group of the clutch is worn, the piston of the hydraulic actuator can ensure that the release bearing abuts against the clutch by further moving in the axial direction, without replacing any component, which significantly reduces maintenance costs.

While possible embodiments are exemplarily described in the above description, it should be understood that there are numerous variations of the embodiments still through all known and furthermore easily conceivable combinations of technical features and embodiments by the skilled person. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. The technical teaching for converting at least one exemplary embodiment is provided more in the foregoing description to the skilled person, wherein various changes may be made without departing from the scope of the claims, in particular with regard to the function and structure of the components.

Reference numeral table

10. Clutch device

20. Transmission shaft

30. Shifting fork

40. Guide rod

50. First hydraulic actuator

51. First shell body

511. First hydraulic chamber

512. Second hydraulic chamber

513. First hydraulic port

514. Second hydraulic port

515. An opening

52. First piston

53. Connecting part

60. Second hydraulic actuator

61. Second shell

611. Hydraulic channel

612. Working chamber

62. Second piston

63. Release bearing

Claims

1. A transfer case includes a clutch release mechanism and a shift mechanism including a fork (30),

it is characterized in that the method comprises the steps of,

the shift mechanism further comprises a first hydraulic actuator (50) for driving the fork (30) and a first hydraulic line for supplying hydraulic fluid to the first hydraulic actuator (50).

2. The transfer case of claim 1, wherein the first hydraulic line is for connection to a transmission for introducing hydraulic fluid from the transmission to the first hydraulic actuator (50).

3. The transfer case of claim 2 wherein the first hydraulic actuator (50) includes a first housing (51) and a first piston (52), the first housing (51) including a first cavity extending in an axial direction, the first piston (52) being axially movably mounted in the first cavity.

4. The transfer case according to claim 3, characterized in that the shift mechanism further comprises a guide rod (40) extending axially through the fork (30), the guide rod (40) being capable of guiding the fork (30) to move axially, the first housing (51) being fixedly connected with the guide rod (40).

5. The transfer case according to claim 3 or 4, characterized in that at least a part of the fork is connected to the first piston (52) through the first housing (51) and that the at least a part of the fork is axially slidable with respect to the first housing (51) following the first piston (52).

6. A transfer case according to claim 3, characterized in that the first piston (52) is moved in an axially middle region of the first cavity, so that two hydraulic chambers (511, 512) are defined in the first cavity, which are located at the axial ends of the first piston (52), respectively.

7. The transfer case according to claim 6, characterized in that the first housing (51) comprises two hydraulic ports (513, 514) communicating with the two hydraulic chambers (511, 512), respectively, the two hydraulic ports (513, 514) being connected to the first hydraulic line, respectively.

8. The transfer case according to any one of claims 1 to 7, characterized in that the clutch release mechanism comprises a second hydraulic actuator (60) for driving a clutch (10) and a second hydraulic line for supplying hydraulic fluid to the second hydraulic actuator (60).

9. The transfer case of claim 8, wherein the second hydraulic line is for connection to a transmission for introducing hydraulic fluid from the transmission to the second hydraulic actuator (60).

10. The transfer case of claim 9 wherein the second hydraulic actuator (60) includes a second housing (61), a second piston (62) and a release bearing (63), the second housing (61) including an axially extending second cavity in which the second piston (62) is axially movably mounted, the second cavity including axially opposite closed and open ends, the release bearing (63) being mounted at an end of the second piston (62) that is oriented toward the open end.