Four-wheel drive system for vehicles

Abstract

To provide a vehicular four-wheel drive device capable of simultaneously improving traveling performance such as bad road running performance and downsizing a structure as a whole.SOLUTION: A vehicular four-wheel drive device comprises: an engine 1; a motor 2; a rear wheel 7 to which driving force can be transmitted from the engine 1; a front wheel 10 to which a driving force can be transmitted from the motor 2; an input shaft 4; a rear output shaft 5 that is coupled to the input shaft 4; a differential mechanism 3 that comprises a sun gear 3s coupled with the motor 2, a ring gear 3r, and a carrier 3c, and performs a differential action with three rotary elements; a front output shaft 9 that outputs driving force transmitted from the carrier 3c to the front wheel 10; a first coupling portion 13 that couples and releases the input shaft 4 and the carrier 3c; and a fixed coupling portion 14 that fixes and release the ring gear 3r.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a four-wheel drive system capable of selectively driving the front and rear four wheels of a vehicle. [Background technology]

[0002] Patent Document 1 describes a device configured to transmit driving force to all wheels of a vehicle for driving. The device described in Patent Document 1 is an all-wheel drive vehicle equipped with a center differential that distributes the output torque of a driving force source consisting of an engine and a first motor / generator to the rear wheels and the front wheels, and is provided with a differential limiting clutch that connects a second motor / generator to the center differential via a driving force distribution change mechanism consisting of a planetary gear mechanism and limits the differential action of the driving force distribution change mechanism. In the device described in Patent Document 1, the ratio of the driving torque transmitted to the rear wheels and the driving torque transmitted to the front wheels can be changed by the positive or negative torque transmitted from the second motor / generator to the center differential. In addition, when the differential limiting clutch is engaged, the entire driving force distribution change mechanism rotates as a unit, and since the driving force distribution change mechanism is connected to the output shaft on the rear wheel side, it is possible to drive as an electric vehicle (EV driving) using the second motor / generator as a driving force source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-246056 A Summary of the Invention [Problem to be solved by the invention]

[0004] The load on the rear and front wheels or the drive torque borne by the wheels varies in various ways depending on the running conditions of the vehicle, such as acceleration / deceleration, turning, and climbing / descending slopes. According to the device described in Patent Document 1, the ratio of the drive torque output by the drive source to be distributed to the rear and front wheels can be continuously changed by the second motor generator, so that the drive torque of the rear and front wheels can be made to match the running conditions of the vehicle, and as a result, running stability, acceleration, and climbing / descending performance can be improved. On the other hand, four-wheel drive vehicles (or all-wheel drive vehicles) are sometimes required to have the ability to run on rough roads such as muddy roads (rough road running performance). In order to meet such requirements, it is necessary to increase the total drive force obtained by all four wheels, and a differential limiting function for the front and rear wheels is also required. In the device described in Patent Document 1, a transmission is provided between the drive source and the center differential, so that the total drive torque can be increased by increasing the gear ratio of the transmission. In addition, in the state where the differential is limited, during EV driving where the vehicle runs only on the second motor generator, the drive torque output by the second motor generator can be distributed and transmitted to all wheels. However, in the state where the differential is limited, the center differential rotates as a whole and outputs the transmitted torque as it is. Therefore, the device described in Patent Document 1 cannot necessarily increase the drive force sufficiently when the vehicle runs in all-wheel drive mode using the second motor generator as a drive force source, and if a torque amplification mechanism is added to improve this, the device will become larger. Thus, in the past, there was room for improvement in terms of so-called rough road driving performance and device miniaturization.

[0005] The present invention has been made in consideration of the above-mentioned technical problems, and has an object to increase the driving force without increasing the size of a vehicle four-wheel drive system configured to transmit driving force from a driving force source to driving wheels via a differential mechanism. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a four-wheel drive system for a vehicle including a first driving force source, a second driving force source, a first driving wheel to which driving force can be transmitted from the first driving force source, and a second driving wheel to which driving force can be transmitted from the second driving force source. The position is a differential mechanism including at least three rotating elements, namely, an input member to which the driving torque of the first driving force source is transmitted, a first output member connected to the input member and outputting the driving torque to the first driving wheel, an input element to which torque from the second driving force source is transmitted, a fixed element selectively connected to a predetermined fixed portion to stop rotation, and an output element which rotates at a reduced speed relative to the input element with the fixed element connected to the fixed portion, and which performs a differential action using the three rotating elements; and a second output member which outputs the driving force transmitted from the output element to the second driving wheel by engaging with the first driving force source and the front Must be fixed The first driving force source and the front driving force source are connected and released from each other. Must be fixed a first connecting part that disconnects the fixing element from the fixing part; and a fixing connecting part that connects the fixing element to the fixing part by engaging with the fixing element and disconnects the fixing element from the fixing part by releasing the fixing connecting part. another connecting portion that connects the output element and the second output member by engaging with it and disconnects the output element and the second output member by releasing it; and a further connecting portion that connects the output element and the first output member by engaging with it and disconnects the output element and the first output member by releasing it. The first connection part and the other connecting part Engage and said fixed connection part and the further other connecting part a first driving mode in which the first driving force source is disengaged and the driving torque output by the first driving force source is transmitted to the first driving wheel and the second driving wheel; part and the further other connecting part Release and said fixed connection part and the other connecting part a second driving mode in which the vehicle is driven by the second driving force source being engaged and the driving torque output by the second driving force source being amplified by the differential mechanism and transmitted to the second driving wheels; and a two-wheel drive state in which one of the first connecting portion and the fixed connecting portion is engaged and the other is released, and the other connecting portion is released and the still other connecting portion is engaged, thereby transmitting drive torque output from the first driving force source and the second driving force source to the first driving wheel and traveling. The present invention is characterized in that it is configured to be configurable. Effect of the Invention

[0007] In the present invention, the first link part and the other connecting part Engage and said fixed connection part and the further other connecting part a first driving mode in which the drive torque output by the first drive force source is transmitted to the first drive wheel and the second drive wheel by disengaging the first drive force source; part and the further other connecting part Release and said fixed connection part and the other connecting part A second driving mode can be set in which, by engaging the first driving force source, the driving torque output by the second driving force source is amplified by the differential mechanism and transmitted to the second driving wheels for driving. Therefore, when the present invention is applied to a hybrid vehicle in which the first driving force source is an internal combustion engine and the second driving force source is a motor or a motor-generator (hereinafter, these will be collectively referred to as a motor), the driving force when driving with the motor can be made sufficiently large, and a special mechanism for increasing the driving force is not required, making the overall configuration of the device smaller and lighter. Furthermore, when driving with the internal combustion engine as the first driving force source, the driving torque can be distributed to the first and second driving wheels by the differential mechanism, in which case the driving torque can be adjusted by the torque of the second driving force source, and if the motor has a power generation function, the motor can generate electricity and recover energy. Furthermore, a two-wheel drive state can be set in which one of the first connecting portion and the fixed connecting portion is engaged and the other is released, and the other connecting portion is released and the further other connecting portion is engaged, thereby transmitting drive torque output by the first driving force source and the second driving force source to the first driving wheel for traveling. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a skeleton diagram showing an example of a configuration assumed in one embodiment of the present invention, in which (A) shows a state in which a first driving mode is set, and (B) shows a state in which a second driving mode is set. [Diagram 2] FIG. 2 is a nomographic diagram for explaining the operating state of the configuration example shown in FIG. 1, in which (A) shows a state in which a first driving mode is set, and (B) shows a state in which a second driving mode is set. [Diagram 3] FIG. 2 is a skeleton diagram showing a second configuration example that is a premise of an embodiment of the present invention. [Figure 4] FIG. 13 is a skeleton diagram showing a third configuration example that is a premise of an embodiment of the present invention. [Diagram 5] FIG. 13 is a skeleton diagram showing a fourth configuration example that is a premise of an embodiment of the present invention. [Figure 6] FIG. 13 is a skeleton diagram showing a fifth configuration example that is a premise of an embodiment of the present invention. [Figure 7] FIG. 13 is a skeleton diagram showing a sixth configuration example that is a premise of an embodiment of the present invention. [Figure 8]FIG. 1 is a skeleton diagram showing one embodiment of the present invention. [Figure 9] FIG. 13 is a skeleton diagram showing another embodiment of the present invention. [Figure 10] FIG. 11 is a skeleton diagram showing yet another embodiment of the present invention, in which (A) shows a state in which a driving mode is set in which the front and rear four wheels are driven by the engine and motor, (B) shows a state in which a driving mode is set in which the differential mechanism is set to a low gear and the rear wheels are driven by the engine and motor, and (C) shows a state in which a driving mode is set in which the differential mechanism is set to a high gear (direct gear) and the rear wheels are driven by the engine and motor. [Figure 11] FIG. 11 is a skeleton diagram showing yet another embodiment of the present invention, in which (A) shows a state in which a driving mode is set in which the front and rear four wheels are driven by the engine and motor, (B) shows a state in which a driving mode is set in which the differential mechanism is set to a low gear and the rear wheels are driven by the engine and motor, and (C) shows a state in which a driving mode is set in which the differential mechanism is set to a high gear (direct gear) and the rear wheels are driven by the engine and motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Next, a specific example of the present invention will be described. Note that the specific example described below is merely one example of the present invention and does not limit the present invention.

[0010] First, a configuration that is a premise of the embodiment of the present invention will be described. (A) and (B) in FIG. 1 show the present invention. The configuration assumed in the embodiment of the present inventionIt is a skeleton diagram showing the main parts, and this four-wheel drive device is mounted on a vehicle equipped with an internal combustion engine (ENG, hereafter referred to as engine) 1 and a motor generator (MG, hereafter referred to as motor) 2 as drive power sources. A differential mechanism 3 is provided to combine the power of the engine 1 and the motor 2. One example of the differential mechanism 3 is a planetary gear mechanism, and FIG. 1 shows a single-pinion planetary gear mechanism. This differential mechanism 3 has rotating elements consisting of a sun gear 3s, which is an external gear, a ring gear 3r, which is an internal gear arranged concentrically with the sun gear 3s, and a carrier 3c, which holds a pinion gear 3p meshed with the sun gear 3s and the ring gear 3r so that the pinion gear 3p can rotate and revolve, and is configured to perform a differential action using these three rotating elements.

[0011] An input shaft 4, which corresponds to the input member in the present invention, to which power is transmitted from an engine 1, which corresponds to the first driving force source in the present invention, is disposed along the central axis of rotation of a differential mechanism 3, and this input shaft 4 is connected to a rear output shaft 5, which corresponds to the first output member in the present invention. The rear output shaft 5 is connected to rear wheels 7, which correspond to the first driving wheels in the present invention, via a final reduction gear 6 and the like. In other words, a driving force is output from the rear output shaft 5 to the rear wheels 7.

[0012] The motor 2, which corresponds to the second driving force source in the present invention, is disposed coaxially with the input shaft 4 and closer to the engine 1 than the differential mechanism 3. The motor 2 is, for example, a permanent magnet type synchronous motor, and its rotor 2R is connected to the sun gear 3s in the differential mechanism 3 by a rotor shaft 8.

[0013] In the example shown in FIG. 1, the carrier 3c in the differential mechanism 3 is an output element, and the carrier 3c is configured to output a driving force to a front output shaft 9, which corresponds to the second output member in the present invention. The front output shaft 9 is arranged in parallel with the input shaft 4 and the rotor shaft 8, and is connected to a front wheel 10, which corresponds to the second driving wheel in the present invention, via a final reduction gear 11 and the like. A suitable mechanism can be adopted as a transmission mechanism for transmitting torque between the front output shaft 9 and the carrier 3c in the differential mechanism 3 as required, and in the example shown in FIG. 1, a winding transmission mechanism, more specifically, a chain mechanism 12 is used. That is, a driving sprocket 12a is integrated with the carrier 3c, and a driven sprocket 12b is integrated with the front output shaft 9, and a chain 12c is wound around these sprockets 12a and 12b. These sprockets 12a and 12b may have the same diameter, but the diameter of the driven sprocket 12b can be made larger than the diameter of the driving sprocket 12a to function as a reduction mechanism.

[0014] The power transmission device shown in Fig. 1 can set at least two driving modes with different modes of transmission of driving force to the drive wheels 7, 10, and is provided with two connecting parts 13, 14 for this purpose. These connecting parts 13, 14 are for selectively transmitting and blocking torque, and can appropriately adopt various conventionally known configurations such as a configuration for transmitting torque by frictional force or a configuration for transmitting torque by meshing of teeth, and in the example shown in Fig. 1, a meshing type engagement means, i.e., a dog clutch, is used.

[0015] Specifically, the first connecting portion 13 is an engagement mechanism for selectively connecting the input shaft 4 and the ring gear 3r functioning as a fixed element or a reaction element, and includes a hub 13a (hereinafter sometimes referred to as a ring gear hub) integrally provided with the ring gear 3r, a hub 13b (hereinafter sometimes referred to as an input hub) integrally provided with the input shaft 4 (or the rear output shaft 5), and a sleeve 13c that moves in the axial direction on the outer periphery of the hubs 13a and 13b to mesh with spline teeth formed on the outer periphery of the hubs 13a and 13b. By moving the sleeve 13c leftward as shown in FIG. 1A by an actuator (not shown), the sleeve 13c meshes with the hubs 13a and 13b, and the ring gear 3r is connected to the input shaft 4 or the rear output shaft 5. That is, the first connecting portion 13 is engaged. Conversely, by moving it to the right as shown in FIG. 1(B), the engagement between the sleeve 13c and the ring gear hub 13a is released, the first connecting portion 13 is released, and the connection between each hub 13a, 13b (the connection between the ring gear 3r and the input shaft 4 or the rear output shaft 5) is released.

[0016] The other connecting part 14 is an engagement mechanism for fixing the ring gear 3r, and will be referred to as the fixed connecting part 14 below. The fixed connecting part 14 has a hub (hereinafter, sometimes referred to as the second ring gear hub) 14a that is integral with the ring gear 3r, a predetermined fixed part 15 such as a casing on which spline teeth are formed, and a sleeve 14b that selectively meshes with the second ring gear hub 14a and the fixed part 15 by moving in the axial direction. As shown in Fig. 1A, by moving this sleeve 14b to the left by an actuator (not shown), the sleeve 14b comes off the second ring gear hub 14a or the fixed part 15, and the fixed connecting part 14 is released, and the ring gear 3r is released from the fixed part and becomes rotatable. Furthermore, as shown in FIG. 1B, the sleeve 14b is moved to the right by an actuator (not shown) so as to mesh with the second ring gear hub 14a and the fixed portion 15, whereby the fixed connecting portion 14 enters an engaged state, and the ring gear 3r is connected to the fixed portion 15, thereby stopping (fixing) the rotation of the ring gear 3r.

[0017] In the four-wheel drive device according to the present invention described above, since it is provided with the two connecting parts 13, 14, a number of drive modes can be set according to the engaged and disengaged states of these connecting parts 13, 14. For example, it is possible to set a driving mode in which the driving torque output by the engine 1 is transmitted to the rear wheels 7 and distributed via the differential mechanism 3 to the motor 2 and the front wheels 10 to drive the four wheels, and a driving mode in which the driving torque output by the motor 2 is amplified by the differential mechanism 3 and transmitted to the front wheels 10.

[0018] FIG. 1A shows a state where a driving mode is set in which the engine 1 drives the front and rear four wheels and the engine 1 and the motor 2 are connected via the differential mechanism 3. This driving mode can be called a split mode and corresponds to the first driving mode in the present invention. This first driving mode is set by releasing the fixed connecting part 14 to release the connection between the ring gear 3r and the fixed part 15, and engaging the first connecting part 13 to connect the ring gear 3r to the input shaft 4 (engine 1). The operating state of the differential mechanism 3 in this first driving mode is shown in FIG. 2A in a collinear diagram. As is conventionally known, the collinear diagram shows each rotating element constituting the differential mechanism 3 with vertical lines, the interval between the lines corresponds to the gear ratio (the ratio between the number of teeth of the sun gear and the number of teeth of the ring gear) in the planetary gear mechanism constituting the differential mechanism 3, and further shows the rotation speed at the position from the base line of the vertical lines showing each rotating element.

[0019] In the differential mechanism 3, the driving torque output by the engine 1 is input to the ring gear 3r, so that the ring gear 3r is an input element, and the carrier 3c is connected to the front wheel 10 via the chain mechanism 12, so that the carrier 3c is an output element, and the motor 2 outputs torque as an electric motor (motor), so that a torque is applied to the sun gear 3s in a direction that increases its rotation speed, so that the sun gear 3s is a reaction element. In other words, in the differential mechanism 3, the driving torques of the engine 1 and the motor 2 are combined. Also, as shown in FIG. 2A, the rotation speed of the ring gear 3r is a rotation speed corresponding to the engine rotation speed or the rotation speed of the rear wheel 7, and the rotation speed of the carrier 3c is a rotation speed corresponding to the rotation speed of the front wheel 10, and the rotation speed of the sun gear 3s, i.e., the rotation speed of the motor 2, is a rotation speed determined by the rotation speeds of the ring gear 3r and the carrier 3c, and the gear ratio of the planetary gear mechanism constituting the differential mechanism 3.

[0020] In the first driving mode, as described above, the engine 1 and the motor 2 both function as driving force sources, so that the overall driving force of the vehicle is large. In addition, all wheels (four wheels), i.e., the rear wheels 7 and the front wheels 10, are driven wheels, so that the vehicle's rough-road performance and driving stability are improved. Furthermore, the rear wheels 7 are driven by the engine 1, and the front wheels 10 are driven by the driving force transmitted from the differential mechanism 3 to which the driving torque is input from the engine 1 and the motor 2, so that the vehicle is in a state similar to when the differential mechanism 3 is limited in differential motion, and no situation occurs in which torque is lost from either the front or rear wheels 7, 10, and in this respect as well, the vehicle's rough-road performance is improved.

[0021] On the other hand, FIG. 1B shows a state in which a so-called low speed ratio driving mode is set in which the differential mechanism 3 functions as a reduction mechanism to amplify the driving torque output by the motor 2 and transmit it to the front wheels 10. This driving mode corresponds to the second driving mode in the present invention. In this second driving mode, in order to make the differential mechanism 3 function as a reduction mechanism, the fixed connecting portion 14 is engaged to connect the ring gear 3r to the fixed portion 15 to fix it, and the first connecting portion 13 is released to release the connection between the ring gear 3r and the input shaft 4 or the engine 1. This state is shown in FIG. 2B by a collinear diagram, and in the differential mechanism 3, the ring gear 3r is a fixed element, whereas the driving torque of the motor 2 is input to the sun gear 3s, making the sun gear 3s an input element, and the carrier 3c is an output element. Therefore, the driving torque of the motor 2 is amplified from the carrier 3c and output to the front wheels 10. On the other hand, since the first connecting portion 13 is released and the connection between the ring gear 3r and the engine 1 is released, the engine 1 can drive only the rear wheels 7.

[0022] Therefore, in the second driving mode, the vehicle can run as a front-wheel drive vehicle using only the motor 2 as a driving force source, or as an all-wheel drive vehicle (four-wheel drive vehicle) by driving the engine 1 in addition to the motor 2. In either case, the driving torque output from the motor 2 is amplified by the differential mechanism 3 and transmitted to the front wheels 10, so that the overall driving force of the vehicle can be increased, and starting acceleration, for example, can be improved. Furthermore, if the motor 2 is made to function as a generator during deceleration, energy is regenerated from the front wheels 10, which are subjected to a large braking torque, so that regeneration efficiency can be improved.

[0023] And this Clear and assumed In the above-described four-wheel drive system, the differential mechanism 3 functions as a power distribution mechanism and a reduction mechanism to set a variety of driving modes. This makes it possible to reduce the number of components required to improve driving stability, rough-road driving performance, starting acceleration, energy efficiency, etc., and therefore to simplify and lighten the structure of the entire system or the entire vehicle.

[0024] The present invention can be practiced by maintaining the basic configuration and varying the configuration and arrangement of the connecting parts 13, 14 or the arrangement of the chain mechanism (transmission mechanism) 12 from the specific example described above, and such examples are described below. Note that in the example described below, the rear wheels 7, front wheels 10, and front and rear final reduction gears 6, 11 have the same configuration as in the specific example described above, so their description and illustration will be omitted.

[0025] In the example shown in Fig. 3, the arrangement order (arrangement order in the longitudinal direction of the vehicle) of the motor 2, the chain mechanism (transmission mechanism) 12, the differential mechanism 3, and each of the connecting parts 13, 14 is reversed from the order shown in Fig. 1. That is, the input shaft 4 is arranged coaxially with the rotational center axis of the engine 1, the input hub 13b is provided at the end of the input shaft 4 on the engine 1 side, and the differential mechanism 3 is arranged adjacent to the input hub 13b and on the rear side of the vehicle. The first connecting part 13 and the fixed connecting part 14 are arranged in this order from the front side in the longitudinal direction of the vehicle on the outer periphery of the input hub 13b and the differential mechanism 3. The chain mechanism 12 is arranged on the rear side of the vehicle of the differential mechanism 3 and the fixed connecting part 14, and the motor 2 is arranged on the rear side of the vehicle of the chain mechanism 12.

[0026] The configuration shown in Fig. 3 can be operated in the same way as the example shown in Fig. 1 described above, and therefore can provide the same actions and effects as the example shown in Fig. 1. In particular, in the configuration shown in Fig. 3, the chain mechanism 12 is disposed on the vehicle front side relative to the motor 2, which tends to have a long shaft length, so that the front output shaft 9 extending from the chain mechanism 12 to the vehicle front side can be shortened.

[0027] The example shown in Fig. 4 is an example in which an engagement mechanism for integrating the entire differential mechanism 3 is added to the configuration shown in Fig. 1. That is, as shown in Fig. 4, a second connecting portion 16 is provided for selectively connecting the sun gear 3s and the carrier 3c in the differential mechanism 3, and this second connecting portion 16 is formed of a friction engagement mechanism such as a multi-plate clutch.

[0028] In the configuration shown in FIG. 4, a driving mode can be set in which the first connecting portion 13 and the fixed connecting portion 14 are released and the second connecting portion 16 is engaged. In this case, the differential mechanism 3 rotates as a whole as a unit by connecting two of its rotating elements. Therefore, the driving torque output by the motor 2 is transmitted to the front wheels 10 without being increased or decreased by the differential mechanism 3. In other words, the differential mechanism 3 does not function as a speed change mechanism, or serves as a power transmission mechanism with a speed change ratio of "1". As a result, when traveling using the motor 2 alone or together with the engine 1 as a driving force source, the rotation speed of the motor 2 is lower than when decelerating by the differential mechanism 3, so that the motor rotation speed at high vehicle speeds can be reduced to improve the power consumption rate (electricity cost). Also, in the configuration shown in FIG. 4, the driving torque output by the motor 2 can be transmitted to the chain mechanism 12 without passing through the differential mechanism 3. Therefore, the torque applied to the differential mechanism 3 is small, and the differential mechanism 3 can be made smaller in size. It should be noted that even with the configuration shown in FIG. 4, the same actions and effects can be obtained by operating it in the same manner as with the configuration shown in FIG.

[0029] In order to integrate the entire differential mechanism 3, at least two of the rotating elements may be connected. Therefore, the second connecting portion 16 may be configured to connect the carrier 3c and the ring gear 3r as shown in FIG. 5, or to connect the sun gear 3s and the ring gear 3r as shown in FIG. 6, in addition to the configuration shown in FIG. 4, in which the sun gear 3s and the carrier 3c are connected. In either configuration shown in FIG. 5 or FIG. 6, when the vehicle is driven using the motor 2 alone or together with the engine 1 as a driving force source, the rotation speed of the motor 2 is lower than when the vehicle is decelerated by the differential mechanism 3, so that the motor rotation speed at high vehicle speeds can be reduced to improve the power consumption rate (electricity cost). Furthermore, the same action and effect can be obtained by operating the vehicle in the same way as the configuration shown in FIG. 1 described above.

[0030] The example shown in FIG. 7 is an example in which the configuration of the fixed portion 15 is changed from that shown in FIG. 1. In the example shown in FIG. 1, the fixed portion 15 is arranged side by side with the ring gear 3r in the axial direction, and the sleeve 14b is arranged on the outer circumferential side thereof so as to be movable in the axial direction. In contrast to this, in the example shown in FIG. 7, the fixed portion 15 is provided on the outer circumferential side of the second ring gear hub 14a, and spline teeth are formed on the inner surface (the surface facing the ring gear 3r) of the fixed portion 15. Spline teeth are formed on both the inner and outer circumferential surfaces of the sleeve 14b, and the sleeve 14b is inserted between the second ring gear hub 14a and the fixed portion 15 to engage with the second ring gear hub 14a and the fixed portion 15 to connect them, and the sleeve 14b is removed from between the second ring gear hub 14a and the fixed portion 15 in the axial direction to release the connection between them. Therefore, in the configuration shown in FIG. 7, the number of parts arranged in the axial direction is reduced, making it possible to shorten the overall axial length of the four-wheel drive device.

[0031] figure FIG. 8 shows an embodiment of the present invention based on the above-mentioned configuration. The example shown here is as follows: This is an example of a configuration in which the rear wheel 7 is driven by the motor 2 in addition to the engine 1. More specifically, in the configuration shown in FIG. 8, in addition to the configuration shown in FIG. 1, the carrier 3c and the drive sprocket 12a of the chain mechanism 12 are selectively connected. The first link is another 3. A connecting portion 18 selectively connects the carrier 3c and the input shaft 4. As another connecting part, A fourth connecting portion 19 is additionally provided. These connecting portions 18, 19 may be meshing engagement mechanisms or friction engagement mechanisms, and in the example shown in Fig. 8, the third connecting portion 18 is configured by a dog clutch, and the fourth connecting portion 19 is configured by a friction engagement mechanism.

[0032] 8, by releasing the first connecting portion 13 and the third connecting portion 18 and engaging the fixed connecting portion 14 and the fourth connecting portion 19, the motor 2 is connected to the rear output shaft 5 or the rear wheel 7 in addition to the engine 1. That is, in the differential mechanism 3, the ring gear 3r is connected to the fixed portion 15 and fixed, and the carrier 3c is disconnected from the chain mechanism 12 (or the front wheel 10) while being connected to the input shaft 4 or the rear output shaft 5, and in this state, the driving torque is input from the motor 2 to the sun gear 3s. Therefore, the differential mechanism 3 functions as a reduction mechanism with the sun gear 3s as an input element, the ring gear 3r as a fixed element, and the carrier 3c as an output element, so that the driving torque output by the motor 2 is amplified by the differential mechanism 3 and output from the rear output shaft 5 to the rear wheel 7. Since the engine 1 is connected to the rear output shaft 5 via the input shaft 4, the vehicle is in a two-wheel drive state in which the rear wheel 7 is driven by the driving torque of the engine 1 and the motor 2 to run. Even in this case, the driving torque output by the motor 2 can be amplified by the differential mechanism 3, so that a large driving force can be obtained.

[0033] The example shown in FIG. 9 is an example in which the second connecting portion 16 described above is added to the configuration shown in FIG. 8. With the configuration shown in FIG. 9, the entire differential mechanism 3 can be rotated as an integrated unit by engaging the second connecting portion 16. Therefore, the entire differential mechanism 3 is integrated by engaging the second connecting portion 14 with the fixed connecting portion 14 and the third connecting portion 18 in a released state, and in this state, the differential mechanism 3 that rotates as an integrated unit is connected to the input shaft 4 or the rear output shaft 5 by engaging the first connecting portion 13 or the fourth connecting portion 19. That is, the motor 2 is connected to the input shaft 4 or the rear output shaft 5. As a result, the driving torque of the motor 2 in addition to the engine 1 is transmitted to the rear wheels 7, and the vehicle is in a two-wheel drive state in which the rear wheels 7 are driven to travel. In this case, the differential mechanism 3 does not function as a speed change mechanism, or serves as a power transmission mechanism with a gear ratio of "1", so the rotation speed of the motor 2 becomes lower than when decelerating using the differential mechanism 3. As a result, the motor rotation speed at high vehicle speeds can be reduced, thereby improving the power consumption rate (electricity efficiency).

[0034] The example shown in Fig. 10 is an example in which the first connecting portion 13, the second connecting portion 16, and the fourth connecting portion 19, which connect the ring gear 3r and the input shaft 4, in the configuration shown in Fig. 9, are configured to share components. Specifically, a carrier hub 16a, which is integrated with the carrier 3c and has spline teeth formed on its outer circumferential surface, is provided between the ring gear hub 13a and the input hub 13b. A sleeve 13c, which is a part of the first connecting portion 13, is long enough to mesh only with the ring gear hub 13a, and a sleeve 19a, which is spaced apart from the sleeve 13c in the axial direction, is provided so that the two move in the axial direction together. The sleeve 19a is long enough to simultaneously mesh with the ring gear hub 13a, the carrier hub 16a, and the input hub 13b, which are aligned in the axial direction. The spacing between these sleeves 13c, 19a is set so that when the sleeve 13c constituting the first connecting portion 13 is engaged with the ring gear hub 13a, the sleeve 19a engages with the input hub 13b, and when the sleeve 13c is disengaged from the ring gear hub 13a of the first connecting portion 13, the sleeve 19a engages with the input hub 13b and the carrier hub 16a, or engages with the ring gear hub 13a, the carrier hub 16a, and the input hub 13b simultaneously. The other configurations are the same as those shown in FIG. 9.

[0035] Fig. 10(A) shows a state in which a running mode that can be called a split mode similar to the running mode shown in Fig. 1(A) described above is set. In this running mode, the sleeve 13c corresponding to the first connecting portion 13 meshes with the ring gear hub 13a, and the sleeve 19a integral with this sleeve 13c meshes with the input hub 13b, connecting the ring gear 3r to the input shaft 4 (or the rear output shaft 5). In addition, the fixed connecting portion 14 is released, and the third connecting portion 18 is engaged, connecting the carrier 3c to the chain mechanism 12.

[0036] The travel mode set as shown in Fig. 10(A) corresponds to the first travel mode in the present invention, and in this first travel mode, the engine 1 and the motor 2 both function as driving force sources, so that the overall driving force of the vehicle is large. In addition, all wheels (four wheels), i.e., the rear wheels 7 and the front wheels 10, are driven wheels, so that the rough-road running performance and running stability are improved. Furthermore, the rear wheels 7 are driven by the engine 1, and the front wheels 10 are driven by the driving force transmitted from the differential mechanism 3 to which the driving torque is input from the engine 1 and the motor 2, so that the state is the same as when the differential mechanism 3 is limited in differential motion, and a situation such as torque loss from either the front or rear wheels 7, 10 does not occur, and in this respect as well, the rough-road running performance is improved.

[0037] FIG. 10B shows a mode in which the vehicle travels in a two-wheel drive state in which the rear wheels 7 are driven by the driving torque of the engine 1 and the motor 2. In this travel mode, the front wheels 10 are disconnected from the differential mechanism 3 because the third connecting portion 18 is released, and no driving force is transmitted to the front wheels 10. The fixed connecting portion 14 is in an engaged state, and the ring gear 3r is fixed, so that the differential mechanism 3 functions as a reduction mechanism. Furthermore, the sleeves 13c and 19a, which are integral with each other, move one pitch to the left in FIG. 10 from the position shown in FIG. 10A described above, and the sleeve 13c comes off the ring gear hub 13a, and the sleeve 19a meshes with the input hub 13b and the carrier hub 16a, connecting the carrier 3c to the input shaft 4 (or the rear output shaft 5).

[0038] Therefore, the driving torque output by the motor 2 is amplified by the differential mechanism 3, output from the carrier 3c, and transmitted to the input shaft 4 (or rear output shaft 5). In other words, since the differential mechanism 3 functions as a reduction mechanism, this driving mode becomes a so-called low-speed mode (low mode). Note that, when the engine 1 is driven, the driving torque is transmitted to the rear wheels 7 via the input shaft 4 and the rear output shaft 5, so that a two-wheel drive state with large driving force can be achieved with both the engine 1 and the motor 2 as driving force sources.

[0039] Fig. 10C shows a state in which a so-called high-speed (direct-coupled) mode (high mode) driving mode is set, in which the differential mechanism 3 is rotated as a whole as a unit to eliminate the deceleration function of the differential mechanism 3 or to function as a transmission with a gear ratio of "1". Explaining this driving mode in comparison with the state shown in Fig. 10B described above, the fixed connecting portion 14 is released, the sleeve 19a is engaged with the three ring gear hubs 13a arranged in the axial direction, the carrier hub 16a and the input hub 13b, and the operating states of the other connecting portions are the same as those shown in Fig. 10B.

[0040] Therefore, the differential mechanism 3 rotates as a whole integrally by connecting the carrier 3c and the ring gear 3r. The carrier 3c is connected to the input shaft 4 (or the rear output shaft 5) via the sleeve 19a and the input hub 13b. Therefore, the driving torque output by the motor 2 is transmitted to the rear wheels 7 from the rear output shaft 5 without being increased or decreased, although it passes through the differential mechanism 3. In other words, the high speed (direct drive) mode (or high mode) is entered. Therefore, the motor rotation speed at high vehicle speeds can be reduced more than in the low mode, thereby improving the power consumption rate (electricity efficiency).

[0041] 10, the ring gear 3r and the connecting portion for selectively connecting the carrier 3c and the input shaft 4 (or the rear output shaft 5) are configured to share parts, which reduces the number of components of the four-wheel drive device as a whole, simplifying the configuration and reducing the weight.

[0042] Fig. 11 shows an example of the configuration shown in Fig. 10, in which the fixed connecting part 14 and the third connecting part 18 share the same components to simplify the configuration. Specifically, the third connecting part 18 is composed of a driving side hub 18a integrated with the driving sprocket 12a of the chain mechanism 12, a second carrier hub 18b integrated with the carrier 3c, and a sleeve 18c that moves in the axial direction to connect and disconnect these hubs 18a, 18b. The sleeve 18c is connected to the sleeve 14b of the fixed connecting part 14 so as to move in the axial direction integrally with the sleeve 14b. The distance between these sleeves 18c, 14b is set to set the following state.

[0043] That is, when the sleeve 18c meshes with the drive side hub 18a and the second carrier hub 18b to engage the third connecting portion 18, the sleeve 14b of the fixed connecting portion 14 disengages from the second ring gear hub 14a and the fixed portion 15, releasing the fixed connecting portion 14. This state is shown in Figure 11(A).

[0044] Furthermore, when the sleeve 14b of the fixed connecting part 14 is engaged with the second ring gear hub 14a and the fixed part 15, the sleeve 18c of the third connecting part 18 disengages from both the drive side hub 18a and the second carrier hub 18b, releasing the third connecting part 18. This state is shown in Figure 11(B).

[0045] Furthermore, when the sleeve 18c of the third connecting part 18 is engaged only with the drive side hub 18a, the sleeve 14b of the fixed connecting part 14 disengages from the second ring gear hub 14a and the fixed part 15, releasing the fixed connecting part 14. This state is shown in Figure 11(C).

[0046] 11, a common actuator can be used to engage and disengage the fixed connecting portion 14 and the third connecting portion 18. With this configuration, the number of components of the four-wheel drive device as a whole can be reduced, making it possible to reduce the size and weight of the device.

[0047] Although examples of the present invention have been described above, it goes without saying that the present invention is not limited to the above-mentioned specific examples, and the specific configuration of each connecting portion may be appropriately changed, and the arrangement or layout of the motor, transmission mechanism, or differential mechanism may be appropriately changed. For example, the differential mechanism 3 may be configured with a double-pinion type planetary gear mechanism instead of the so-called single-pinion type planetary gear mechanism described above.

[0048] It should be noted that the present invention described above as a specific example is The assumed configuration is The list is as follows:

[0049] In addition to the configuration described in the claims, the vehicle four-wheel drive device further includes a second connecting part that connects at least two rotating elements in the differential mechanism to integrate the entire differential mechanism when the fixed connecting part is in a released state. With this configuration, the rotation speed of the driving force source can be reduced by setting a so-called high speed stage (direct drive stage) or high mode in which the differential mechanism outputs torque without increasing or decreasing it. Accordingly, the energy efficiency, also known as fuel efficiency and electric power consumption, of the driving force source can be improved.

[0050] The second connecting portion is a four-wheel drive device for a vehicle that is configured using a friction engagement mechanism.

[0051] A four-wheel drive device for a vehicle, wherein the friction engagement mechanism constituting the second connecting portion is controlled to a slip state so as to change the differential limiting torque of the differential mechanism.

[0052] In a four-wheel drive device for a vehicle, the second connecting portion is configured to selectively connect the input element and the output element. With this configuration, when the entire differential mechanism is integrated, the torque input to the differential mechanism is output via the second connecting portion, so that the torque applied to the differential mechanism is reduced, and as a result, the differential mechanism can be made smaller.

[0053] In the vehicle four-wheel drive device, the second connecting portion is configured to selectively connect the sun gear and the ring gear. With this configuration, the torque applied to the second connecting portion can be reduced, thereby making the second connecting portion smaller in size.

[0054] In a four-wheel drive device for a vehicle, the fixed portion and the fixed connecting portion are disposed on the outer periphery side of the differential mechanism. With this configuration, the number of components disposed side by side in the axial direction is reduced, and therefore the axial length can be shortened.

[0055] A four-wheel drive device for a vehicle, wherein the first connecting portion and the differential mechanism are arranged on the same axis as the first driving force source, and the first connecting portion is arranged on the opposite side of the differential mechanism from the first driving force source.

[0056] A four-wheel drive device for a vehicle, wherein the second connecting portion and the differential mechanism are arranged on the same axis as the first driving force source, and the second connecting portion is arranged on the opposite side of the differential mechanism from the first driving force source.

[0057] A four-wheel drive device for a vehicle in which an input member is constituted by an input shaft to which power is input from a first drive source such as an engine, and a differential mechanism is disposed coaxially with the input shaft.

[0058] The vehicle four-wheel drive device further includes a transmission mechanism that connects the output element in the differential mechanism and the second output member.

[0059] A four-wheel drive device for a vehicle further comprising a third connecting part that selectively connects the drive side member and the output element in the transmission mechanism, the drive side member, the output element and the third connecting part are arranged on the same axis as the first drive force source, and the transmission mechanism is arranged closer to the first drive force source than the third connecting part. With this configuration, the transmission mechanism is arranged on the front side of the vehicle, so the axial length of the second output member such as the front output shaft can be shortened.

[0060] A four-wheel drive device for a vehicle in which the second driving force source and the differential mechanism are arranged on the same axis, and the second driving force source is arranged rearward of the differential mechanism. With this configuration, the number of components arranged forward of the differential mechanism is reduced, making it possible to shorten the axial length of the output member that transmits driving force from the differential mechanism to the second drive wheels.

[0061] A vehicle four-wheel drive device further comprising a third connecting portion that selectively connects the output element and the second output member, and a fourth connecting portion that selectively connects the output element and the first output member. With this configuration, even when the first drive wheel is driven by the second drive power source, the drive force can be increased by the differential mechanism, and the rotation speed of the second drive power source can be suppressed or reduced by not causing the deceleration action of the differential mechanism.

[0062] A four-wheel drive device for a vehicle in which any two of the connecting parts are arranged side by side in the axial direction and adjacent to each other, and some of the components of the two connecting parts are shared by the two connecting parts. With this configuration, the number of components of the four-wheel drive device as a whole can be reduced, thereby making the device more compact. [Explanation of symbols]

[0063] 1 Engine 2 Motors 2R rotor 3 Differential mechanism 3c Carrier 3p pinion gear 3r ring gear 3s sun gear 4 Input Shaft 5 Rear output shaft 6,11 Final gearbox 7 Rear wheel 8 Rotor shaft 9 Front output shaft 10 Front wheel 12 Chain mechanism 13 Connecting part 13a Ring gear hub 13b Input Hub 13c Sleeve 14 Fixed connection 14a ring gear hub 14b Sleeve 15 Fixed part 16 2nd connection part 16a Carrier hub 18 Connecting part 18a Drive side hub 18b Carrier hub 18c sleeve 19 4th connection part 19a Sleeve

Claims

1. A four-wheel drive device for a vehicle including a first driving force source, a second driving force source, a first driving wheel to which driving force can be transmitted from the first driving force source, and a second driving wheel to which driving force can be transmitted from the second driving force source, an input member to which the driving torque of the first driving force source is transmitted; a first output member connected to the input member and configured to output a driving torque to the first driving wheel; a differential mechanism including at least three rotating elements, namely, an input element to which torque is transmitted from the second driving force source, a fixed element selectively connected to a predetermined fixed portion to stop rotation, and an output element that rotates at a reduced speed relative to the input element in a state in which the fixed element is connected to the fixed portion, and which performs a differential action using the three rotating elements; a second output member that outputs the driving force transmitted from the output element to the second drive wheel; a first connecting portion that connects the first driving force source and the fixed element by engaging with the first connecting portion and disconnects the first driving force source and the fixed element by releasing the first connecting portion; a fixing coupling part that engages to couple the fixing element to the fixing part and releases to disconnect the fixing element from the fixing part; another coupling portion that couples the output element to the second output member by engaging with the output element and that couples the output element to the second output member by releasing the coupling therebetween; a further coupling portion that couples the output element to the first output member by engaging the further coupling portion and that couples the output element to the first output member by releasing the further coupling portion; Equipped with A first driving mode in which the first connecting portion and the other connecting portion are engaged and the fixed connecting portion and the further other connecting portion are released, and the driving torque output by the first driving force source is transmitted to the first driving wheel and the second driving wheel to travel; a second driving mode in which the first connecting portion and the other connecting portion are released and the fixed connecting portion and the further other connecting portion are engaged, and the driving torque output by the second driving force source is amplified by the differential mechanism and transmitted to the second driving wheel to travel; and a two-wheel drive state in which one of the first connecting portion and the fixed connecting portion is engaged and the other is released, and the further other connecting portion is released and the further other connecting portion is engaged, and the driving torque output by the first driving force source and the second driving force source is transmitted to the first driving wheel to travel.

1. A vehicle four-wheel drive system comprising:

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