Driving force transmitting device

Abstract

A driving force transmitting device (2) according to the present disclosure is for transmitting the driving force of a motor (1) installed in a vehicle to wheels, and comprises a sleeve (23), an idler gear (24), a linear motion mechanism (3), and a brush (4). The sleeve (23) is slidable in the extension direction of, and non-rotatable in the circumferential direction of, a shaft member (20) involved in the transmission of driving force. The idler gear (24) has clutch teeth (25) that mate with the sleeve (23), and is inserted loosely into the shaft member (20). The linear motion mechanism (3) drives the sleeve (23) along the extension direction of the shaft member (20) to interrupt / allow the transmission of driving force between the shaft member (20) and the idler gear (24). The brush (4) contacts a case (5) of the driving force transmitting device (2) and the linear motion mechanism (3).

Description

Drive force transmission device

[0001] The present invention relates to a driving force transmission device that transmits driving force from a motor mounted on a vehicle to wheels.

[0002] It is known that in vehicles equipped with a traction motor, electromagnetic inverter noise resulting from inverter operation propagates through the power transmission path, potentially generating acoustic noise (radio noise) in the output of the vehicle's radio. The inverter noise is transmitted along the power transmission path via the motor's output shaft, and is radiated into the surrounding area using the drive shaft and suspension as antennas. Therefore, it has been proposed to suppress the propagation of inverter noise by electrically grounding the power transmission path by providing a body earth from the power transmission path to the vehicle body (see Patent Documents 1 to 3).

[0003] JP 2000-310296 A JP 2006-320129 A JP 2014-147293 A

[0004] In Patent Document 1, the motor rotor shaft is supported on the case using a conductive bearing filled with conductive grease, thereby electrically grounding the power transmission path. However, conductive bearings are disadvantageous in terms of durability and maintainability compared to ordinary bearings, and are also expensive. In Patent Documents 2 and 3, the power transmission path is electrically grounded using a carbon brush that slides against the rotating shaft. However, the carbon brush that slides against the rotating shaft is subject to severe wear and requires regular replacement and maintenance.

[0005] One of the objects of the present invention, which was devised in light of the above-mentioned problems, is to provide a driving force transmission device that can suppress the propagation of inverter noise while improving durability and maintainability. However, in addition to this object, another object of the present invention is to achieve effects derived from the configurations shown in the "Description of Embodiments" below, which are effects that cannot be obtained with conventional technology.

[0006] The disclosed driving force transmission device can be realized as the following disclosed embodiments (application examples), which solve at least part of the above-mentioned problems. Each of the embodiments from embodiment 2 onwards is an embodiment that can be selected as an additional option, and each of the embodiments from embodiment 2 onwards is an embodiment that can be omitted. None of the embodiments from embodiment 2 onwards discloses an embodiment or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed driving force transmission device transmits the driving force of a motor, and includes a sleeve that is slidable in the extension direction of a shaft member related to the transmission of the driving force and non-rotatable in the circumferential direction, an idling gear that has clutch teeth that engage with the sleeve and is loosely inserted into the shaft member, a linear motion mechanism that drives the sleeve along the extension direction of the shaft member to connect and disconnect the transmission of the driving force between the shaft member and the idling gear, and a brush that contacts a case of the driving force transmission device and the linear motion mechanism.

[0008] Aspect 2. With regard to aspects including Aspect 1 above, it is preferable that the driving force transmission device includes a gear chamber in which the sleeve and the idler gear are disposed, and that the brush is disposed outside the gear chamber. Aspect 3. With regard to aspects including Aspect 1 above, it is preferable that the linear motion mechanism includes a link shaft formed in a cylindrical shape having a cylindrical axis extending parallel to the extension direction of the shaft member, and that the brush is fixed in a state where it is pressed against the outer cylindrical surface of the link shaft.

[0009] Aspect 4. In the aspects including Aspect 1 above, it is preferable that the shaft member is a reduction shaft disposed adjacent to a motor shaft to which rotation of the motor is input.

[0010] According to the disclosed driving force transmission device, by bringing the brush into contact with the case of the driving force transmission device and the linear motion mechanism, it is possible to suppress wear on the brush while suppressing the transmission of inverter noise, thereby improving the durability and maintainability of the driving force transmission device.

[0011] It is a schematic diagram showing the structure of the driving force transmission device according to the embodiment. It is a cross-sectional view showing the inside of the driving force transmission device. It is a cross-sectional view of a brush built into the driving force transmission device. It is a schematic diagram showing the structure of the driving force transmission device according to a modified example.

[0012] The disclosed driving force transmission device transmits driving force from a motor mounted on a vehicle to wheels. Specific examples of vehicles to which the driving force transmission device can be applied include electric vehicles and hybrid vehicles. The driving force transmission device can be applied to hybrid vehicles (HEVs) equipped with an engine, a motor, and a battery, and plug-in hybrid vehicles (PHEVs).

[0013] A plug-in hybrid vehicle is a hybrid vehicle that can externally charge its battery or receive external power from the battery. A plug-in hybrid vehicle is equipped with a charging port (inlet) for inserting a charging cable that supplies power from an external charging facility and an outlet for external power supply.

[0014] [1. Configuration] Fig. 1 is a schematic diagram showing the structure of a driving force transmission device 2 according to an embodiment. The driving force transmission device 2 is applied to a hybrid vehicle equipped with an engine (not shown) and a motor 1 as a driving source. In Fig. 1, the power transmission path for transmitting the driving force of the engine to the drive wheels is omitted.

[0015] The driving force transmission device 2 is installed on a power transmission path that transmits the driving force of the motor 1 to the drive wheels. The driving force transmission device 2 functions as a reducer that reduces the speed of rotation output from the motor 1 and increases the torque. The motor 1 is, for example, a three-phase AC synchronous motor. AC power for driving the motor 1 is generated by an inverter (not shown) and supplied to the motor 1.

[0016] The inverter is a converter (DC-AC inverter) that converts between power (DC power) from a DC circuit in which a driving battery (not shown) is installed and power (AC power) from an AC circuit in which the motor 1 is installed. Inside the inverter, for example, a three-phase bridge circuit including multiple switching elements and diodes is provided. AC power conversion is achieved by intermittently switching the connection state of the multiple switching elements. Note that inverter noise is generated by the on / off operation of these switching elements.

[0017] The driving force transmission device 2 includes a motor shaft 10 and a reduction shaft 20. The motor shaft 10 is a rotating shaft to which the rotation of the motor 1 is input, and the reduction shaft 20 is a rotating shaft that transmits rotation that is reduced in speed compared to the motor shaft 10. Both the motor shaft 10 and the reduction shaft 20 are shaft members involved in transmitting the driving force of the motor 1, and are rotatably provided inside a metal case 5. The reduction shaft 20 is disposed, for example, adjacent to the motor shaft 10 and parallel to the motor shaft 10. A motor gear 11 is fixed to the motor shaft 10 to transmit the rotation of the motor shaft 10 to the reduction shaft 20.

[0018] The reduction shaft 20 includes a clutch mechanism 21, a reduction gear 24, and an output gear 26. The reduction gear 24 has clutch teeth 25 (gear piece) that mate with a sleeve 23 (described later), and is an idling gear that is loosely inserted into the reduction shaft 20 while meshing with the motor gear 11. The clutch mechanism 21 is a power connection / disconnection mechanism that switches between a state in which the reduction gear 24 is rotatable relative to the reduction shaft 20 and a state in which the reduction gear 24 is unable to rotate relative to the reduction shaft 20 (i.e., a state in which the reduction gear 24 rotates integrally with the reduction shaft 20). The output gear 26 is a gear that meshes with a drive shaft gear 7 fixed to the drive shaft 6 of the drive wheels.

[0019] When the clutch mechanism 21 connects the reduction gear 24 and the reduction shaft 20, the rotation of the motor gear 11 is transmitted to the reduction shaft 20 via the reduction gear 24, and the rotation is transmitted to the drive wheels via the output gear 26, the drive shaft gear 7, and the drive shaft 6. When the clutch mechanism 21 disconnects the reduction gear 24 from the reduction shaft 20, the reduction gear 24 rotates freely relative to the reduction shaft 20, and the transmission of driving force from the motor 1 to the drive wheels is interrupted.

[0020] The clutch mechanism 21 has a hub 22, a sleeve 23, and a linear motion mechanism 3. The hub 22 is a cylindrical member having splines (concave and recessed grooves, outer teeth, extending in the axial direction of the reduction shaft 20) on its outer circumferential surface, and is fixed to the reduction shaft 20. The sleeve 23 is a cylindrical member having splines (internal teeth) on its inner circumferential surface. The sleeve 23 is provided so as to be slidable relative to the outer circumferential surface of the hub 22 in the extension direction (axial direction) of the reduction shaft 20, but is non-rotatable in the rotation direction (circumferential direction) of the reduction shaft 20.

[0021] The clutch teeth 25 are provided on the reduction gear 24 so as to be able to engage with and disengage from the sleeve 23. The clutch teeth 25 are formed, for example, in a cylindrical shape with splines on the outer circumferential surface and are fixed to the reduction gear 24. Alternatively, the clutch teeth 25 are formed in a shape that constitutes a known synchromesh mechanism. For example, the clutch teeth 25 are formed in a shape that has splines on the outer circumferential surface and a conical or cylindrical surface that realizes synchronous rotation with the reduction gear 24, and are provided so as to be able to rotate relative to the reduction gear 24 with a predetermined friction force. When the rotational speed difference between the reduction gear 24 and the clutch teeth 25 is large, the clutch teeth 25 slide against the reduction gear 24 via the conical or cylindrical surface, gradually reducing the rotational speed difference. Furthermore, when the rotational speed difference between the reduction gear 24 and the clutch teeth 25 decreases, the reduction gear 24 and the clutch teeth 25 rotate synchronously together.

[0022] The linear motion mechanism 3 is a mechanism for reciprocatingly driving (linearly moving) the sleeve 23 along the extension direction of the reduction shaft 20 to connect or disconnect the transmission of driving force between the reduction shaft 20 and the reduction gear 24. The linear motion mechanism 3 functions to move the sleeve 23 in a direction of contact (approaching or moving away from) with respect to the clutch teeth 25. The linear motion mechanism 3 brings the sleeve 23 close to the clutch teeth 25 and engages them, thereby integrating the hub 22 and the reduction gear 24 and connecting the reduction shaft 20 and the reduction gear 24. This allows the driving force of the motor 1 to be transmitted to the reduction shaft 20. On the other hand, the linear motion mechanism 3 moves the sleeve 23 away from the clutch teeth 25 and disengages them, thereby disconnecting the reduction shaft 20 and the reduction gear 24. This prevents the driving force of the motor 1 from being transmitted to the reduction shaft 20.

[0023] 2 is a cross-sectional view showing the interior of the driving force transmission device 2. The driving force transmission device 2 includes a gear chamber 29 in which at least a sleeve 23 and a reduction gear 24 are disposed. The reduction shaft 20 is supported on the case 5, for example, within the gear chamber 29 via a plurality of shaft bearings 27. The reduction gear 24 is supported on the reduction shaft 20 via a needle bearing 28 that is annularly mounted on the outer circumferential surface of the reduction shaft 20. Lubricating oil (oil) is supplied to the interior of the gear chamber 29 to lubricate sliding parts of the reduction shaft 20, clutch mechanism 21, reduction gear 24, etc.

[0024] The linear motion mechanism 3 has a fork 31, a link shaft 32, and an actuator 33. The fork 31 is a member that engages with the sleeve 23, and has, for example, a U-shaped portion that circumscribes the outer periphery of the sleeve 23, a rod-shaped portion that extends from the U-shaped portion toward the outside in the radial direction of the reduction shaft 20, and a cylindrical portion that is provided at the tip of the rod-shaped portion and is fitted and fixed to the link shaft 32.

[0025] The link shaft 32 is a member for sliding the entire fork 31 along the extension direction of the reduction shaft 20. The link shaft 32 is formed in a tubular shape (for example, a cylindrical or rectangular tubular shape) having a tubular axis that extends parallel to the extension direction of the reduction shaft 20. The fork 31 (tubular portion) is fixed to one end of the link shaft 32, and the actuator 33 is connected to the other end of the link shaft 32.

[0026] The actuator 33 is a drive device that slides the link shaft 32 in its axial direction. The power source of the actuator 33 may be an electric motor or a hydraulic pump. The other end of the link shaft 32 (the end connected to the actuator 33) preferably extends through the case 5 of the driving force transmission device 2 to the outside of the gear chamber 29. The actuator 33 is also preferably disposed outside the gear chamber 29.

[0027] The actuator 33 functions to drive the link shaft 32 and engage the sleeve 23 with the clutch teeth 25 when the vehicle's driving mode is, for example, an EV driving mode (a mode in which the vehicle runs using only the driving force of the motor 1). The actuator 33 also functions to drive the link shaft 32 and disengage the sleeve 23 from the clutch teeth 25 when the vehicle's driving mode is, for example, an ENG driving mode (a mode in which the vehicle runs using only the driving force of the engine).

[0028] The driving force transmission device 2 of this embodiment includes a brush 4 that contacts the case 5 and the linear motion mechanism 3. The brush 4 is a noise removal brush that removes inverter noise that is propagated along the power transmission path via the motor shaft 10 and the reduction shaft 20. The linear motion mechanism 3 is electrically grounded (body earthed) to the case 5 and the vehicle body via the brush 4. As shown in FIG. 2 , the brush 4 is preferably disposed outside the gear chamber 29. This prevents contact between the lubricating oil in the gear chamber 29 and the brush 4 (reduction in conductivity due to the lubricating oil).

[0029] 3 is a cross-sectional view of the brush 4. The brush 4 includes a main body 41, a carbon brush 42, a spring 43, a conductive wire 44, and a bracket 45. The main body 41 is formed of, for example, an insulating resin. The main body 41 has a cylindrical cavity large enough to accommodate the carbon brush 42. The carbon brush 42 is a conductive member made of a solidified mixture of carbon, metal, resin, etc., and is disposed inside the cylindrical cavity formed in the main body 41.

[0030] The spring 43 is an elastic member that biases the carbon brush 42 toward the outside of the cylindrical cavity. The carbon brush 42 is fixed in place with its tip pressed against the object to be contacted by the spring 43. The conductive wire 44 is a member that connects the carbon brush 42 to a bracket 45. The bracket 45 is a metal fitting that is attached in contact with the case 5 and is made of, for example, a conductive metal.

[0031] [2. Effects] (1) The driving force transmission device 2 of this embodiment transmits the driving force of a motor 1 mounted on a vehicle to wheels, and includes a sleeve 23, a reduction gear 24 (idle gear), a linear motion mechanism 3, and a brush 4. The sleeve 23 is provided slidable in the extension direction of a shaft member (reduction shaft 20 in this embodiment) involved in the transmission of driving force but unrotatable in the circumferential direction. The reduction gear 24 has clutch teeth 25 that engage with the sleeve 23 and is loosely inserted on the reduction shaft 20. The linear motion mechanism 3 drives the sleeve 23 along the extension direction of the reduction shaft 20 to connect and disconnect the transmission of driving force between the reduction shaft 20 and the reduction gear 24. The brush 4 contacts a case 5 of the driving force transmission device 2 and the linear motion mechanism 3.

[0032] In this way, by bringing the brush 4 into contact with the case 5 of the driving force transmission device 2 and the linear motion mechanism 3, the reduction shaft 20 connected to the linear motion mechanism 3 can be electrically grounded. Furthermore, when the driving force of the motor 1 is being transmitted to the drive shaft 6, the engagement between the sleeve 23 and the clutch teeth 25 allows the motor shaft 10 and the reduction shaft 20 to be electrically grounded. This makes it possible to suppress the propagation of inverter noise resulting from the operation of the inverter.

[0033] Furthermore, because the brush 4 comes into contact with the linear motion mechanism 3, wear on the brush 4 can be suppressed compared to when the brush 4 is in sliding contact with, for example, the motor shaft 10 or the reduction shaft 20, thereby improving the durability of the brush 4 and the driving force transmission device 2. Furthermore, for example, the frequency of replacement and maintenance of the carbon brush 42 and the spring 43 can be reduced, improving the maintainability of the brush 4 and the driving force transmission device 2. Furthermore, expensive conductive bearings such as those described in Patent Document 1 are not required, thereby reducing costs.

[0034] (2) The driving force transmission device 2 described above includes a gear chamber 29 in which the sleeve 23 and the reduction gear 24 are disposed. As shown in FIG. 2, the brush 4 is disposed outside the gear chamber 29. This prevents contact between the lubricating oil in the gear chamber 29 and the brush 4 (reduction in conductivity due to the lubricating oil). This prevents performance degradation and quality deterioration of the brush 4 due to the lubricating oil, further improving the durability and maintainability of the brush 4.

[0035] (3) The linear motion mechanism 3 has a cylindrical link shaft 32 having a cylindrical axis extending parallel to the extension direction of the reduction shaft 20. The brush 4 is fixed in a state where it is pressed against the outer cylindrical surface of the link shaft 32. The position of the outer cylindrical surface of the link shaft 32 does not change even if the sleeve 23 is moved along the extension direction of the reduction shaft 20. In other words, because the brush 4 is fixed in a state where it is pressed against the outer cylindrical surface whose position does not change, the position of the main body 41 of the brush 4 and the load acting on the spring 43 can be stabilized. Therefore, deformation of the main body 41 of the brush 4 and deterioration of the spring 43 due to driving of the linear motion mechanism 3 can be suppressed, and the durability and maintainability of the brush 4 can be further improved.

[0036] (4) In the driving force transmission device 2 described above, the clutch mechanism 21 is applied to the reduction shaft 20, which is disposed adjacent to the motor shaft 10 to which the rotation of the motor 1 is input. That is, the shaft member to which the sleeve 23 and the reduction gear 24 are applied is the reduction shaft 20, which is electrically grounded to the case 5 and the vehicle body via the brush 4. By grounding the reduction shaft 20 to the body in this manner, inverter noise transmitted to the drive shaft 6 and suspension downstream of the reduction shaft 20 can be reduced compared to when the motor shaft 10 is grounded to the body. This enhances the inverter noise suppression effect.

[0037] [3. Other] The above-described embodiments are merely illustrative and are not intended to exclude various modifications or applications of techniques not explicitly described in the present embodiments. Each configuration of the present embodiments can be modified in various ways without departing from the spirit of the present embodiments. Furthermore, each configuration of the present embodiments can be selected as needed, or can be appropriately combined with various configurations included in known techniques.

[0038] In the above embodiment, the driving force transmission device 2 is applied to a hybrid vehicle, but the vehicle to which the driving force transmission device 2 is applied is not limited to a hybrid vehicle. The driving force transmission device 2 can be applied to a vehicle equipped with at least a motor 1. Furthermore, in the above embodiment, a structure in which the brush 4 is in contact with the linear motion mechanism 3 that drives the clutch mechanism 21 provided on the reduction shaft 20 has been described, but the position of the linear motion mechanism 3 that the brush 4 is in contact with can be changed as appropriate. In other words, the linear motion mechanism 3 may be disposed on a shaft member other than the reduction shaft 20.

[0039] Furthermore, in the above embodiment, the clutch mechanism 21 related to the connection and disconnection of the driving force has been described in detail, but the function of the clutch mechanism 21 is not limited thereto. For example, the brush 4 may be brought into contact with a linear motion mechanism that drives the clutch mechanism related to the speed change of the driving force. Fig. 4 is a schematic diagram showing the structure of a driving force transmission device 50 according to a modified example. This driving force transmission device 50 includes a linear motion mechanism 51 that drives a clutch mechanism 61 provided on a motor shaft 60 (shaft member), and the brush 4 is provided so as to come into contact with this linear motion mechanism 51.

[0040] The driving force transmission device 50 includes a motor shaft 60 and a reduction shaft 70. The motor shaft 60 is a rotating shaft to which the rotation of the motor 1 is input, and the reduction shaft 70 is a rotating shaft that transmits rotation that is reduced in speed compared to the motor shaft 60. A first reduction gear 71, a second reduction gear 72, and an output gear 73 are fixed to the reduction shaft 70. The first reduction gear 71 and the second reduction gear 72 are gears that correspond to different reduction ratios and have different numbers of teeth and radii. The output gear 73 is a gear that meshes with a drive shaft gear 7 fixed to the drive shaft 6 of the drive wheel.

[0041] The motor shaft 60 includes a clutch mechanism 61, a first motor gear 64, and a second motor gear 66. The first motor gear 64 has first clutch teeth 65 that mate with a sleeve 63 (described later), and is an idling gear that is loosely inserted onto the motor shaft 60 while meshed with a first reduction gear 71. The second motor gear 66 has second clutch teeth 67 that mate with a sleeve 63 (described later), and is an idling gear that is loosely inserted onto the motor shaft 60 while meshed with a second reduction gear 72.

[0042] The clutch mechanism 61 is a power connection / disconnection mechanism for switching between a state in which the first motor gear 64 rotates integrally with the motor shaft 60, a state in which the second motor gear 66 rotates integrally with the motor shaft 60, and a state in which the first motor gear 64 and the second motor gear 66 are rotatable relative to the motor shaft 60. The clutch mechanism 61 has a hub 62, a sleeve 63, and a linear motion mechanism 51. The configurations of the hub 62, the sleeve 63, the first clutch teeth 65, and the second clutch teeth 67 are similar to the configurations of the hub 22, the sleeve 23, and the clutch teeth 25 described above, and therefore description thereof will be omitted.

[0043] In this way, even in the driving force transmission device 50 in which the clutch mechanism 61 is provided on the motor shaft 60, by bringing the brush 4 into contact with the case 5 and the linear motion mechanism 51, it is possible to suppress the propagation of inverter noise resulting from the operation of the inverter and improve the durability and maintainability of the brush 4 and the driving force transmission device 50. Note that even if a linear motion mechanism 51 that drives the clutch mechanism 61 provided on the reduction shaft 70 (shaft member) is provided and the brush 4 is provided so as to come into contact with this linear motion mechanism 51, it is possible to obtain the same effects as in this modified example.

[0044] This invention can be used in the manufacturing industry of driving force transmission devices that transmit the driving force of a motor mounted on a vehicle to the wheels, and can be used in the manufacturing industry of vehicles equipped with motors and driving force transmission devices, and the manufacturing industry of vehicle drive systems (powertrains).

[0045] REFERENCE SIGNS LIST 1 Motor 2 Driving force transmission device 3 Linear motion mechanism 4 Brush 5 Case 6 Drive shaft 7 Drive shaft gear 10 Motor shaft (shaft member) 11 Motor gear 20 Reduction shaft (shaft member) 21 Clutch mechanism 22 Hub 23 Sleeve 24 Reduction gear (idling gear) 25 Clutch teeth 26 Output gear 27 Shaft bearing 28 Needle bearing 29 Gear chamber 31 Fork 32 Link shaft 33 Actuator 41 Main body 42 Carbon brush 43 Spring 44 Conductive wire 45 Bracket 50 Driving force transmission device 60 Motor shaft (shaft member) 61 Clutch mechanism 62 Hub 63 Sleeve 64 First motor gear 65 First clutch teeth 66 Second motor gear 67 Second clutch teeth 70 Reduction shaft (shaft member) 71 First reduction gear 72 Second reduction gear 73 Output gear

Claims

1. A driving force transmission device that transmits the driving force of a motor mounted on a vehicle to wheels, comprising: a sleeve that is slidable in the extension direction of a shaft member involved in the transmission of the driving force but is unable to rotate circumferentially; an idling gear that has clutch teeth that engage with the sleeve and is loosely inserted into the shaft member; a linear motion mechanism that drives the sleeve along the extension direction of the shaft member to connect and disconnect the transmission of the driving force between the shaft member and the idling gear; and a brush that contacts the case of the driving force transmission device and the linear motion mechanism.

2. A driving force transmission device according to claim 1, characterized in that it comprises a gear chamber in which the sleeve and the idler gear are arranged, and the brush is arranged outside the gear chamber.

3. A driving force transmission device according to claim 1, characterized in that the linear motion mechanism has a link shaft formed in a cylindrical shape with a cylindrical axis extending parallel to the extension direction of the shaft member, and the brush is fixed in a state where it is pressed against the outer cylindrical surface of the link shaft.

4. The driving force transmission device according to claim 1, wherein the shaft member is a reduction shaft disposed adjacent to the motor shaft to which rotation of the motor is input.

Images