JP2008189110A - Power transmission device of four-wheel drive car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch a shift mechanism arranged between a transfer of a four-wheel drive car and a driven wheel differential to three states of direct coupling, acceleration and deceleration. <P>SOLUTION: The shift mechanism 120 has coaxially a transfer side input shaft 121, a driven wheel differential side output shaft 131 and two planetary gear mechanisms 122 and 132. A carrier 125 of the first mechanism 122 is joined to the input shaft 121, and a carrier 135 of the second mechanism 132 is joined to the output shaft 131, and mutual ring gears 126 and 136 of both mechanisms 122 and 132 are connected. A first clutch 127 engaging and disengaging a sun gear 123 and the input shaft 121 of the first mechanism 122, a second clutch 137 engaging and disengaging a sun gear 133 and the output shaft 131 of the second mechanism 132, a first brake 128 engaging and disengaging the sun gear 123 and a shift mechanism case 120a of the first mechanism 122, and a second brake 138 engaging and disengaging the sun gear 133 and the shift mechanism case 120a of the second mechanism 132, are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a four-wheel drive vehicle, in particular, an output transmitted from a drive source to a main drive wheel axle is transferred to a slave drive wheel axle, and a difference in rotational speed between the main drive wheel side and the slave drive wheel side The present invention relates to a technical field of a power transmission device for a four-wheel drive vehicle having a structure provided with a speed change mechanism for solving the problem.

  Conventionally, the output of the engine as a drive source passes through the transmission regardless of whether it is based on FF (front engine / front drive), FR (front engine / rear drive), or RR (rear engine / rear drive). After that, while being transmitted to the main drive wheel axle through the main drive wheel differential, it is taken out by the transfer to the propulsion shaft, and is transmitted from the propulsion shaft to the slave drive wheel axle via the slave drive wheel differential. Four-wheel drive vehicles are known.

  On the other hand, in a four-wheel drive vehicle, assuming that the tire diameters are all the same, if there is a difference in rotational speed between the front wheels and the rear wheels, that is, if there is a difference in peripheral speed, the circulation torque will increase. Since problems such as power loss and unnecessary heat generation of the drive system occur, it is customary to replace all tires simultaneously with tires of the same brand and size at the time of tire replacement. However, even in such a case, a difference in tire diameter may occur due to variations in tire wear due to long-term use, changes in tire load, and the like. In this case, a difference in rotational speed between front and rear wheels occurs.

  For this problem, for example, it is conceivable to use the technique described in Patent Document 1. That is, the ratio between the rotational speed of the main driving wheel side and the rotational speed of the driven wheel side is set between the transfer on the power transmission path between the main driving wheel axle and the driven driving wheel axle and the driven driving wheel differential. A speed change mechanism for changing is interposed. When a rotational speed difference occurs between the rotational speed of the main drive wheel and the rotational speed of the slave drive wheel, the speed change mechanism is controlled so as to cancel it, thereby avoiding problems such as an increase in circulating torque. .

Japanese Examined Patent Publication No. 7-64219 (page 3, left column, line 5 to same page right column, line 13)

  By the way, the speed change mechanism described in Patent Document 1 includes a direct coupling clutch that directly connects and disconnects an input shaft on the main drive wheel side (transfer side) and an output shaft on the slave drive wheel side (slave drive wheel differential side); When the speed increasing clutch is disconnected by connecting the direct coupling clutch, the input shaft and the output shaft are connected to each other. While directly connected to the same rotational speed, when the direct clutch is disengaged and the speed increasing clutch is connected, the rotational speed of the input shaft is increased at a predetermined gear ratio and transmitted to the output shaft. Yes.

  However, there are still problems to be solved. First, the rotational speed of the input shaft cannot be reduced and transmitted to the output shaft. The difference in rotational speed generated between the front and rear wheels is not always that the rotational speed on the main drive wheel side is large and the rotational speed on the slave drive wheel side is small, but conversely the rotational speed on the slave drive wheel side is large Therefore, the speed change mechanism is required to be able to reduce the rotational speed of the input shaft and transmit it to the output shaft. Next, the speed increasing ratio or the speed reducing ratio is fixed in advance by the number of teeth of the gear train. Since the rotational speed difference generated between the front and rear wheels varies depending on the situation, it is desired that the speed ratio of the speed change mechanism can be changed steplessly on either the speed increasing side or the speed reducing side. .

  Therefore, the present invention switches between three states of direct connection, acceleration, and deceleration between the input shaft on the main drive wheel side and the output shaft on the slave drive wheel side in the transmission mechanism mounted on the four-wheel drive vehicle. It is an object of the present invention to make it possible and to change the gear ratio steplessly on both the speed increasing side and the speed reducing side.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a transfer for distributing the output of a drive source to a main drive wheel axle and a slave drive wheel axle, and a slave drive wheel provided between the left and right slave drive wheels. A power transmission device for a four-wheel drive vehicle having a differential and a transmission mechanism provided between the transfer and the driven wheel differential, wherein the transmission mechanism inputs power from the transfer side. And an output shaft that is arranged coaxially with the input shaft and outputs power to the driven wheel differential side, and first and second planetary gear sets arranged coaxially with the input shaft and the output shaft, The pinion carrier of the first planetary gear set is coupled to the input shaft, the pinion carrier of the second planetary gear set is coupled to the output shaft, and the ring gears of the first and second planetary gear sets A first clutch that connects and disconnects the sun gear of the first planetary gear set and the input shaft, a second clutch that connects and disconnects the sun gear of the second planetary gear set and the output shaft, and A first brake for connecting / disconnecting the sun gear of the one planetary gear set and the transmission mechanism case and a second brake for connecting / disconnecting the sun gear of the second planetary gear set and the transmission mechanism case are provided.

  A second aspect of the present invention is the power transmission device for a four-wheel drive vehicle according to the first aspect, wherein the first clutch and the second clutch are engaged, and the first brake and the first Control means for continuously changing the speed ratio of the speed change mechanism to the speed increasing side by lowering the capacity of the first clutch and increasing the capacity of the first brake from a state where the two brakes are not engaged. It is characterized by being.

  Next, a third aspect of the present invention is the power transmission device for a four-wheel drive vehicle according to the first aspect, wherein the first clutch and the second clutch are engaged, and the first brake and the first There is provided control means for steplessly changing the speed ratio of the speed change mechanism to the deceleration side by lowering the capacity of the second clutch and increasing the capacity of the second brake from a state where the two brakes are not engaged. It is characterized by.

  Next, the invention according to claim 4 is the power transmission device for a four-wheel drive vehicle according to claim 2 or 3, wherein the control means controls the capacity of the clutch whose capacity has not been reduced. The transmission torque capacity from the transfer side to the driven wheel differential side is changed steplessly.

  Next, a fifth aspect of the present invention is the power transmission device for a four-wheel drive vehicle according to the first aspect, wherein the main drive wheel speed detecting means for detecting the rotational speed of the main drive wheel, and the slave Slave drive wheel speed detection means for detecting the rotation speed of the drive wheel, rotation speed of the main drive wheel detected by the main drive wheel speed detection means, and rotation of the slave drive wheel detected by the slave drive wheel speed detection means Control means for controlling the first clutch, the second clutch, the first brake, and the second brake is provided so that the speed has a predetermined correspondence relationship.

  First, according to the first aspect of the invention, the first, second clutch and the first, second brake are controlled in the speed change mechanism mounted between the transfer of the four-wheel drive vehicle and the driven wheel differential. By doing so, it becomes possible to switch between the input shaft on the main drive wheel side and the output shaft on the slave drive wheel side into three states of direct connection, acceleration, and deceleration.

  This will be specifically described with reference to FIG. The speed change mechanism 120 has an input shaft 121 to which power is input from the transfer side and an output shaft 131 from which power is output to the driven wheel differential side, and both shafts 121 and 131 are arranged coaxially. Further, a first planetary gear set 122 and a second planetary gear set 132 are provided coaxially with both shafts 121 and 131. In that case, the pinion carrier 125 of the first planetary gear set 122 is coupled to the input shaft 121, and the pinion carrier 135 of the second planetary gear set 132 is coupled to the output shaft 131. Further, the ring gears 126 and 136 of the planetary gear sets 122 and 132 are connected to each other. That is, the first planetary gear set 122 is a carrier 125 input / ring gear 126 output, and the second planetary gear set 132 is a ring gear 136 input / carrier 135 output. The first clutch 127 that connects and disconnects the sun gear 123 of the first planetary gear set 122 and the input shaft 121, the second clutch 137 that connects and disconnects the sun gear 133 and the output shaft 131 of the second planetary gear set 132, and the first planetary gear set 122. A first brake 128 for connecting / disconnecting the sun gear 123 and the transmission mechanism case 120a and a second brake 138 for connecting / disconnecting the sun gear 133 of the second planetary gear set 132 and the transmission mechanism case 120a are provided.

  Therefore, if both clutches 127 and 137 are engaged and both brakes 128 and 138 are not engaged (released), the entire planetary gear sets 122 and 132 are integrated together, and the ring gears 126 and 136 are connected to each other. Therefore, after all, the input shaft 121 and the output shaft 131 are integrated to obtain a direct connection state. Further, when the capacity of the first clutch 127 is decreased and the capacity of the first brake 128 is increased from this directly connected state, the rotation of the sun gear 123 is decreased in the first planetary gear set 122, and the rotation of the input shaft 121 and the pinion carrier 125 is performed. The rotation of the ring gear 126 becomes larger than that of the ring gear 126. Since the ring gears 126 and 136 are connected to each other, the rotation of the input shaft 121 is eventually increased and transmitted to the output shaft 131, and an accelerated state is obtained. It will be. Conversely, when the capacity of the second clutch 137 is decreased and the capacity of the second brake 138 is increased from the directly connected state, the rotation of the sun gear 133 is decreased in the second planetary gear set 132, and the pinion carrier 135 is rotated more than the rotation of the ring gear 136. And the rotation of the output shaft 131 is reduced. Here, since the ring gears 126 and 136 are connected to each other, the rotation of the input shaft 121 is eventually reduced and transmitted to the output shaft 131 to obtain a deceleration state. It becomes. As described above, the input shaft on the main drive wheel side and the output shaft on the slave drive wheel side can be switched to three states of direct connection, acceleration, and deceleration.

  Next, according to the invention described in claim 2, from the state where the first and second clutches are engaged and the first and second brakes are not engaged, that is, from the direct connection state, the capacity of the first clutch is reduced, By increasing the capacity of the first brake, that is, by weakening the engaging force of the clutch on the input shaft side, and similarly making the brake on the input shaft side connect, the speed ratio of the transmission mechanism is increased as described above. Can be changed to the side. In addition, in that case, the rotation of the sun gear of the first planetary gear set can be freely controlled by variously increasing or decreasing the capacity of the first clutch and the capacity of the first brake. It becomes possible to change the ratio steplessly on the speed increasing side.

  Next, according to the invention described in claim 3, from the state where the first and second clutches are engaged and the first and second brakes are not engaged, that is, from the direct connection state, the capacity of the second clutch is reduced, By increasing the capacity of the second brake, that is, by weakening the fastening force of the clutch on the output shaft side and connecting the brake on the output shaft side as well, as described above, the speed ratio of the speed change mechanism is reduced. Can be changed. In addition, in this case, the rotation of the sun gear of the second planetary gear set can be freely controlled by adjusting the capacity of the second clutch and the capacity of the second brake in various ways. It becomes possible to change the ratio steplessly on the deceleration side.

  Next, according to the invention of claim 4, by controlling the capacity of the second clutch of the invention of claim 2 or the capacity of the first clutch of the invention of claim 3, that is, By controlling the fastening force of the clutch on the output shaft side at the time of acceleration and controlling the fastening force of the clutch on the input shaft side at the time of deceleration, the transfer side (main drive wheel side) to the driven wheel differential side (slave drive wheel side) ) Can be changed. In addition, in that case, it is possible to steplessly change the transmission torque capacity from the transfer side to the driven wheel differential side by adjusting the clutch capacity in various ways. That is, the speed change mechanism according to the present invention has a function equivalent to a known electronically controlled torque distribution type coupling.

  Next, according to the fifth aspect of the present invention, in the speed change mechanism mounted between the transfer of the four-wheel drive vehicle and the sub-drive wheel differential, the first, second clutch and first, second brake are provided. By controlling, the rotation speed of the main drive wheel and the rotation speed of the slave drive wheel can be maintained in a predetermined correspondence relationship, so there are problems such as power loss due to increased circulating torque and unnecessary heat generation of the drive system. Can be accurately suppressed. Hereinafter, the present invention will be described in more detail through the best mode of the invention.

  FIG. 1 is a block diagram showing a power transmission device of a four-wheel drive vehicle 1 according to the preferred embodiment of the present invention. The four-wheel drive vehicle 1 is constructed on the basis of an FF (front engine / front drive) vehicle, and the engine 1 placed horizontally at the front of the vehicle body and the output of the engine 1 are changed according to the operation of the driver. The drive force output from the transmission 2 is transmitted to the front left and right main drive wheel axles 40, 40 or the main drive wheels 50, 50 via the main drive wheel differential 30. ing. On the other hand, the driving force output from the transmission 2 is taken out by a transfer 60 to a propulsion shaft 70 that extends in the front-rear direction of the vehicle body. It is also transmitted to the drive wheel axles 90, 90 or the slave drive wheels 100, 100. An electronic control coupling 110 and a speed change mechanism 120, which is a main feature of the present invention, are arranged in the middle of the propulsion shaft 70 between the transfer 60 at the front of the vehicle body and the driven wheel differential 80 at the rear of the vehicle body. Has been.

  Here, the electronic control coupling 110 freely distributes the driving torque between the front and rear wheels, that is, between the main driving wheel and the sub driving wheel. Although not shown in detail, for example, an electromagnetic solenoid is used to control the control clutch. When coupled, the spherical cam pushes the main cam due to the rotational speed difference between the control cam and the main cam, whereby the main clutch variably couples the transmission torque capacity (for example, Japanese Patent Laid-Open No. 10-292828 and Japanese Patent Laid-Open No. 2006). 300337).

  On the other hand, the speed change mechanism 120 freely changes the rotation speed ratio between the front and rear wheels. As shown in detail in FIG. 2, the speed change mechanism 120 is used to input power to the speed change mechanism 120 from the transfer 60 side of the front of the vehicle body. An input shaft 121 and an output shaft 131 for outputting power from the speed change mechanism 120 to the driven wheel differential 80 at the rear of the vehicle body are provided. The input shaft 121 and the output shaft 131 are arranged coaxially, and further, a front first planetary gear set 122 and a rear second planetary gear set 132 are provided coaxially with the shafts 121 and 131. . These planetary gear sets 122 and 132 include sun gears 123 and 133, a plurality of pinion gears 124 and 134 that mesh with the sun gears 123 and 133, ring gears 126 and 136 that mesh with these pinion gears 124 and 134, and a plurality of pinion gears 124. , 134 and a pinion carrier 125, 135 supporting the known structure.

  In that case, the pinion carrier 125 of the first planetary gear set 122 is coupled to the input shaft 121, and the pinion carrier 135 of the second planetary gear set 132 is coupled to the output shaft 131, and these two planetary gear sets 131, The 132 ring gears 126 and 136 are connected to each other.

  In the first planetary gear set 122, a first clutch 127 is connected between the sun gear 123 and the input shaft 121, and between the sun gear 123 and the transmission mechanism case 120a. A first brake (acceleration brake) 128 for connecting and disconnecting is provided. Similarly, in the second planetary gear set 132, a second clutch 137 for connecting and disconnecting the sun gear 133 and the output shaft 131 is interposed between the sun gear 133 and the transmission mechanism case 120a. A second brake (deceleration brake) 138 for connecting and disconnecting the motor is interposed [Configuration of Claim 1].

  Here, each of the first and second clutches 127 and 137 and the first and second brakes 128 and 138 is configured such that a plurality of friction plates on the inner side and the outer side are in contact with each other in accordance with supply or discharge of hydraulic pressure. The hydraulic oil for providing the hydraulic pressure can be guided to the transmission mechanism 120 from the transmission 20 or the transfer 60, for example. The capacity of the clutches 127 and 137 and the brakes 128 and 138 (friction elements) is controlled by, for example, providing a duty solenoid valve on a hydraulic oil supply circuit, and the duty ratio of the duty solenoid valve (ratio of valve opening time). ) Can be performed by adjusting the increase / decrease.

  As summarized in FIG. 3, in the speed change mechanism 120, the friction elements 127, 137, 128, and 138 are engaged, disengaged (released), or capacity-controlled, so that the input shaft 121 on the transfer 60 side can be controlled. The output shaft 131 on the side of the driven wheel differential 80 can be switched to three states: direct connection, acceleration or deceleration.

  For example, when the first and second clutches 127 and 137 are engaged and the first and second brakes 128 and 138 are not engaged, the first and second planetary gear sets 122 and 132 have the shafts 121 and 131 and the sun gear 123. , 133, the pinion carriers 125, 135, and the ring gears 126, 136 rotate together in the same direction at the same speed. Moreover, since the ring gears 126 and 136 of the first and second planetary gear sets 122 and 132 are connected to each other, the first and second planetary gear sets 122 and 132 are integrated, and as a result, the input shaft 121 and the output shaft A direct connection state in which 131 is directly connected is obtained. FIG. 4 shows a power transmission path inside the speed change mechanism 120 at the time of the direct connection with a bold line.

  In this state, when the capacity of the second clutch 137 is controlled, that is, when the fastening force of the clutch 137 on the output shaft 131 side is controlled, the transfer drive side (main drive wheel 50 side) to the driven drive wheel differential 80 side ( The transmission torque capacity to the driven wheel 100 side) can be changed. In this case, the transmission torque capacity from the transfer 60 side to the driven wheel differential 80 side can be changed steplessly by adjusting the capacity of the second clutch 137 in various ways (during direct connection). Coupling). That is, the electronic control coupling 110 has the same function. FIG. 5 shows a power transmission path inside the speed change mechanism 120 in the coupling at the time of direct coupling by a bold line (the broken line indicates that the capacity is controlled).

  On the other hand, when the capacity of the first clutch 127 is decreased and the capacity of the first brake (acceleration brake) 128 is increased from the directly coupled state of FIG. 4, that is, the fastening force of the first clutch 127 is weakened, and the first brake 128 is When connected, the rotation of the sun gear 123 decreases in the first planetary gear set 122. As a result, the rotation of the input shaft 121 increases, and the output shaft 131 passes from the ring gears 126 and 136 to the output shaft 131 via the second planetary gear set 132. The transmitted acceleration state is obtained. FIG. 6 shows a power transmission path inside the speed change mechanism 120 at the time of the speed increase by a thick line (the broken line indicates that the capacity is controlled).

  In addition, in that case, the rotation of the sun gear 123 of the first planetary gear set 122 can be freely controlled by adjusting the capacity of the first clutch 127 and the capacity of the first brake 128 in various ways. It becomes possible to change the speed ratio of the speed change mechanism 120 steplessly toward the speed increasing side.

  In this state, when the capacity of the second clutch 137 is controlled, that is, when the fastening force of the clutch 137 on the output shaft 131 side is controlled, the transfer drive side (main drive wheel 50 side) to the driven drive wheel differential 80 side ( The transmission torque capacity to the driven wheel 100 side) can be changed. In addition, in that case, the transmission torque capacity from the transfer 60 side to the driven wheel differential 80 side can be changed steplessly by adjusting the capacity of the second clutch 137 in various ways. (Hour coupling) [Structure of Claim 4]. That is, the electronic control coupling 110 has the same function. FIG. 7 shows a power transmission path inside the speed change mechanism 120 in this speed-up coupling in bold lines (the broken line indicates that capacity control is performed).

  In addition, when the capacity of the second clutch 137 is decreased and the capacity of the second brake (deceleration brake) 138 is increased from the directly coupled state of FIG. 4, that is, the fastening force of the second clutch 137 is weakened, and the second brake 138 is connected. As a result, in the second planetary gear set 132, the rotation of the sun gear 133 decreases, and as a result, the rotational speed of the input shaft 121 decreases from the first planetary gear set 122 via the ring gears 126 and 136 to the output shaft 131. A transmitted deceleration state is obtained. FIG. 8 shows a power transmission path inside the speed change mechanism 120 at the time of deceleration with a thick line (the broken line indicates that the capacity is controlled).

  In addition, in that case, the rotation of the sun gear 133 of the second planetary gear set 132 can be freely controlled by adjusting the capacity of the second clutch 137 and the capacity of the second brake 138 in various ways. It becomes possible to change the speed ratio of the speed change mechanism 120 steplessly toward the speed reduction side.

  In this state, when the capacity of the first clutch 127 is controlled, that is, when the fastening force of the clutch 127 on the input shaft 121 side is controlled, the transfer driving side (main driving wheel 50 side) to the driven driving wheel differential 80 side ( The transmission torque capacity to the driven wheel 100 side) can be changed. In this case, the transmission torque capacity from the transfer 60 side to the driven wheel differential 80 side can be changed steplessly by adjusting the capacity of the first clutch 127 in various ways (during deceleration). Coupling) [Structure of Claim 4]. That is, the electronic control coupling 110 has the same function. FIG. 9 shows a power transmission path inside the speed change mechanism 120 in this deceleration coupling in bold lines (the broken line indicates that capacity control is performed).

  In the present embodiment, the internal structure of the speed change mechanism 120 is symmetrical on the input side and the output side. That is, the components 123 to 126 of the first planetary gear set 122 on the input shaft 121 and the components 133 to 136 of the second planetary gear set 132 on the output shaft 131 have the same specifications, and the first clutch 127 and the first clutch The two clutches 137 have the same specifications, and the first brake 128 and the second brake 138 have the same specifications. Thereby, the parts cost and assembly cost of the transmission mechanism 120 can be suppressed.

  Next, a typical example for controlling the transmission mechanism 120 having such a configuration will be described. This control is performed when there is a difference in the tire diameter due to variations in wear or changes in tire load due to long-term use of the tires of the front and rear drive wheels 50, 100, and when a rotational speed difference occurs between the front and rear wheels. The transmission mechanism 120 is controlled so as to cancel it, and problems such as an increase in circulating torque are avoided.

  For this purpose, as shown in FIG. 10, a main drive wheel speed sensor 210 for detecting the rotation speed of the main drive wheel 50 and a slave drive wheel speed sensor 220 for detecting the rotation speed of the slave drive wheel 100 are provided. The control unit 200 inputs signals from these sensors 210 and 220, and the rotation speed (main drive wheel speed) VF of the main drive wheel 50 detected by the main drive wheel speed sensor 210 and the sub drive wheel speed sensor 220. The first and second clutches 127 and 137 and the first and second clutches 120 of the speed change mechanism 120 so that the rotational speed (subordinate driving wheel speed) VR of the subordinate driving wheel 100 detected in step S1 has a predetermined correspondence Ro. The brakes 128 and 138 are configured to be controlled [configuration of claim 5].

  Here, the main driving wheel speed VF and the driven driving wheel speed VR may specifically be the rotation speed of the input shaft 121 and the rotation speed of the output shaft 131 of the speed change mechanism 120, or The average rotation speed of the main drive wheels 50, 50 and the average rotation speed of the left and right slave drive wheels 100, 100 may be used.

  FIG. 11 is a flowchart of the control operation performed by the control unit 200. First, in step S1, the main driving wheel speed sensor 210 and the sub driving wheel speed sensor 220 are used to detect the main driving wheel speed VF and the sub driving wheel speed VR. Next, in step S2, a map is read from a memory (not shown).

  Here, as shown in FIG. 12, the map shows the correspondence R between the main drive wheel speed VF and the slave drive wheel speed VR, more specifically, the ratio of the slave drive wheel speed VR to the main drive wheel speed VF (VR / VF) is a map showing the correlation between the transmission mechanism 120 and the control mode. Specifically, when the ratio R (= VR / VF) is smaller than the target ratio Ro (in the region A), the speed change mechanism 120 is controlled to the speed increasing side (see FIGS. 3 and 6), and the target ratio is set. When larger than Ro (in the region B), the speed change mechanism 120 is controlled to the deceleration side (see FIGS. 3 and 8), and when the target ratio Ro is within a predetermined range (in the region C), the speed is changed. The mechanism 120 is controlled to maintain the current state. Here, the region C is hysteresis provided around the target ratio Ro. The target ratio Ro should be determined as appropriate according to the characteristics of the four-wheel drive vehicle 1 and is necessarily set to “1” even on the assumption that the tire diameters are all the same. Not exclusively.

  Returning to FIG. 11, next, in step S3, it is determined which area of the map. As a result, as described above, in the region A, the transmission mechanism 120 is controlled to the speed increasing side in Step S4, and in the region B, the transmission mechanism 120 is controlled to the deceleration side in Step S5. If C, in step S6, the transmission mechanism 120 is controlled to maintain the current state. Then, by repeating the above operation, the ratio R converges to the target ratio Ro and is maintained.

  Thus, by controlling the first and second clutches 127 and 137 and the first and second brakes 128 and 138 of the speed change mechanism 120, the rotational speed VF of the main drive wheel 50 and the rotational speed VR of the slave drive wheel 100 are controlled. Can be maintained in a predetermined correspondence relationship Ro, so that it is possible to accurately suppress problems such as power loss and unnecessary heat generation of the drive system due to an increase in circulating torque.

  The above embodiment is the best embodiment of the present invention, but various changes and improvements can be added without departing from the scope of the claims. For example, in the above-described embodiment, the four-wheel drive vehicle 1 is constructed on the basis of the FF vehicle, but instead, it may be constructed on the basis of the FR vehicle base or the RR vehicle base. In the above embodiment, the speed change mechanism 120 is disposed in the middle of the propulsion shaft 70 between the transfer 60 and the driven wheel differential 80. Instead, the transfer 60 or the driven wheel differential 80 is provided. May be formed integrally.

  As described above in detail with reference to specific examples, the present invention provides a direct connection between the input shaft on the main driving wheel side and the output shaft on the driven wheel side in the transmission mechanism mounted on the four-wheel drive vehicle. Technical field of power transmission devices for four-wheel drive vehicles, because it is a technology that can switch between three states of speed increase and deceleration and change the gear ratio steplessly on both the speed increasing side and the speed reducing side Is expected to have broad industrial applicability.

It is a block diagram which shows the power transmission device of the four-wheel drive vehicle which concerns on best embodiment of this invention. FIG. 4 is a skeleton diagram showing a configuration of a speed change mechanism disposed between a transfer and a driven wheel differential of the four-wheel drive vehicle. It is a table | surface which shows the relationship between the control aspect of the said transmission mechanism, and the operating state of a friction element. FIG. 3 is a skeleton diagram similar to FIG. 2 when the speed change mechanism is controlled to be in a directly coupled state. Similarly, it is a skeleton diagram when controlling to a direct connection state with a coupling function. Similarly, it is a skeleton diagram when controlling to a speed increasing state. Similarly, it is a skeleton diagram when controlling to a speed increasing state with a coupling function. It is a skeleton diagram when controlling to a deceleration state similarly. Similarly, it is a skeleton diagram when controlling to a deceleration state with a coupling function. It is a control system figure of the four-wheel drive vehicle. It is a flowchart which shows an example of the specific control operation which the control unit of the said four-wheel drive vehicle performs. It is explanatory drawing of the map used by the said control action.

Explanation of symbols

1 Four-wheel drive vehicle 10 Engine 20 Transmission 30 Main drive wheel differential 40 Main drive wheel axle 50 Main drive wheel 60 Transfer 70 Propulsion shaft 80 Sub drive wheel differential 90 Sub drive wheel axle 100 Sub drive wheel 110 Electronically controlled coupling 120 Transmission mechanism 120a Transmission mechanism case 121 Input shaft 122 First planetary gear set 123 Sun gear 124 Pinion gear 125 Pinion carrier 126 Ring gear 127 First clutch 128 First brake (acceleration brake)
131 Output shaft 132 Second planetary gear set 133 Sun gear 134 Pinion gear 135 Pinion carrier 136 Ring gear 137 Second clutch 138 Second brake (deceleration brake)
200 Control unit (control means)
210 Main drive wheel speed sensor (main drive wheel speed detection means)
220 Subordinate driven wheel speed sensor (subordinate driven wheel speed detecting means)
R Ratio of sub-drive wheel speed to main drive wheel speed (correspondence)
Ro target ratio (predetermined correspondence)
VF Main drive wheel speed VR Sub drive wheel speed

Claims (5)

A transfer that distributes the output of the drive source to the main drive wheel axle and the slave drive wheel axle, a slave drive wheel differential provided between the left and right slave drive wheels, and provided between the transfer and the slave drive wheel differential A power transmission device for a four-wheel drive vehicle having a transmission mechanism,
The transmission mechanism is
An input shaft for inputting power from the transfer side;
An output shaft that is arranged coaxially with the input shaft and outputs power to the driven wheel differential side,
The first and second planetary gear sets arranged coaxially with these input shaft and output shaft,
A pinion carrier of the first planetary gear set is coupled to the input shaft;
A pinion carrier of the second planetary gear set is coupled to the output shaft;
The ring gears of the first and second planetary gear sets are connected to each other,
A first clutch that connects and disconnects the sun gear of the first planetary gear set and the input shaft;
A second clutch that connects and disconnects the sun gear of the second planetary gear set and the output shaft;
A first brake for connecting and disconnecting a sun gear and a transmission mechanism case of the first planetary gear set;
A power transmission device for a four-wheel drive vehicle, comprising a second brake for connecting and disconnecting a sun gear of the second planetary gear set and a transmission mechanism case. A power transmission device for a four-wheel drive vehicle according to claim 1,
From the state in which the first clutch and the second clutch are engaged and the first brake and the second brake are not engaged, the capacity of the first clutch is decreased and the capacity of the first brake is increased, A power transmission device for a four-wheel drive vehicle, comprising control means for steplessly changing the speed ratio of the speed change mechanism toward the speed increasing side. A power transmission device for a four-wheel drive vehicle according to claim 1,
From the state in which the first clutch and the second clutch are engaged and the first brake and the second brake are not engaged, the capacity of the second clutch is decreased and the capacity of the second brake is increased. A power transmission device for a four-wheel drive vehicle, comprising control means for steplessly changing the speed ratio of the speed change mechanism toward the deceleration side. A power transmission device for a four-wheel drive vehicle according to claim 2 or 3,
In the four-wheel drive vehicle, the control means continuously changes the transmission torque capacity from the transfer side to the driven wheel differential side by controlling the capacity of the clutch whose capacity has not been reduced. Power transmission device. A power transmission device for a four-wheel drive vehicle according to claim 1,
Main driving wheel speed detecting means for detecting the rotational speed of the main driving wheel;
Slave drive wheel speed detection means for detecting the rotational speed of the slave drive wheel;
The first clutch so that the rotation speed of the main drive wheel detected by the main drive wheel speed detection means and the rotation speed of the slave drive wheel detected by the slave drive wheel speed detection means have a predetermined correspondence relationship. And a control means for controlling the second clutch, the first brake, and the second brake.

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