JP2009001210A - Power transmission device for four-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission device for four-wheel drive vehicle having a simple constitution and increasing or reducing rotation speed of a driven wheel relative to a rotation speed of a main drive wheel. <P>SOLUTION: The power transmission device for the four-wheel drive vehicle has a transmission mechanism 100 provided on a drive force transmission system between a main drive wheel axle and a driven wheel axle. The transmission mechanism 100 is constituted by an input shaft 102 connected to the drive force transmission system on the main drive wheel side; an output shaft 104 connected to a drive force transmission system on the driven wheel side; first and second planetary gear sets 106, 108; one clutch 110; and brakes 112, 114 in normal driving and in reverse driving, respectively. A clutch 110 is fully engaged to directly engage the input shaft 102 with the output shaft 104, and one engaging force of the clutch 110 and the brakes 112, 114 is controlled to control a rotation speed ratio of the input shaft 102 and the output shaft 104. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power transmission device for a four-wheel drive vehicle, and belongs to a technical field of travel control for stabilizing the travel of the four-wheel drive vehicle.

  Conventionally, in a four-wheel drive vehicle, the peripheral speed (tangential speed on the ground contact surface) of each of the main drive wheel and the slave drive wheel is required to be a required peripheral speed ratio (hereinafter referred to as “required peripheral speed ratio”). Some are configured to be.

  For example, there is one described in Patent Document 1. This is to increase the speed of the rear wheels in order to oversteer during turning. Specifically, this four-wheel drive vehicle is a main drive wheel that is a front wheel in order to improve running stability. In order to improve the turning performance at the time of turning, when the peripheral speed of each of the rear driving wheel and the rear driving wheel is made substantially equal (that is, the peripheral speed ratio of the main driving wheel and the sub driving wheel is set to about 1: 1). There are times when the peripheral speed of the driven wheel is increased as compared with the peripheral speed of the main drive wheel (that is, the peripheral speed ratio of the main drive wheel and the slave drive wheel is set to 1: m (m> 1)). . In order to achieve this required peripheral speed ratio, the transmission force transmission system between the main drive wheel axle and the slave drive wheel axle has a transmission, and the transmission includes the main drive wheel axle and the slave drive wheel. The rotational speed ratio of the axle is set to a rotational speed ratio necessary for achieving the required peripheral speed ratio (hereinafter referred to as “required rotational speed ratio”).

Japanese Patent Publication No. 7-64219

  However, the above-described transmission performs acceleration for the rear wheels (sub driven wheels) but does not perform deceleration. However, there is a situation in which it is desired that the transmission in the drive force transmission system between the main drive wheel axle and the slave drive wheel axle execute deceleration on the slave drive wheel.

  For example, even if the rotation speed ratio between the main drive wheel axle and the slave drive wheel axle is set to the required rotation speed ratio, the peripheral speed ratio between the main drive wheel and the slave drive wheel is, for example, 1: 1 due to the change in the diameter of the drive wheel. May deviate from the required peripheral speed ratio. This change in the diameter of the drive wheel is applied to the tire when, for example, a tire with a diameter different from the diameter of the tire to be originally attached is installed in tire replacement, or when the tire wears or the center of gravity of the four-wheel drive vehicle moves. This happens due to changes in load.

  When the diameter of the drive wheel changes in this way and the peripheral speed ratio between the main drive wheel and the slave drive wheel deviates from the required peripheral speed ratio, so-called circulating torque is generated between the two drive wheels due to friction on the road surface. . This circulating torque acts on the driving force transmission system in addition to the original driving torque from the driving source, thereby increasing the rotational resistance in each part of the driving force transmission system. As a result, power loss, that is, deterioration of fuel efficiency of the engine, deterioration of durability of the power transmission system due to heat generation, and the like are caused.

  In order to suppress this circulation torque, it may be desired to request the transmission in the driving force transmission system between the main drive wheel axle and the slave drive wheel axle to perform deceleration on the slave drive wheel.

  Accordingly, an object of the present invention is to provide a power transmission device for a four-wheel drive vehicle capable of increasing and decreasing the rotational speed of the driven wheel axle relative to the rotational speed of the main drive wheel axle.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application includes a drive source, a transfer device that distributes and transmits the output of the drive source to the main drive wheel axle and the slave drive wheel axle, A power transmission device for a four-wheel drive vehicle having a speed change mechanism provided in a drive force transmission system between a drive wheel axle and a slave drive wheel axle,
The transmission mechanism includes an input shaft coupled to a driving force transmission system on the main drive wheel side, an output shaft coupled to a driving force transmission system on the slave drive wheel side, first and second planetary gear sets, A clutch for forward driving and a brake for reverse driving, and the clutch is completely engaged to directly connect the input shaft and the output shaft, and the engagement force of one of the clutch and the brake is And controlling a rotational speed ratio between the input shaft and the output shaft.

According to a second aspect of the present invention, in the power transmission device for a four-wheel drive vehicle according to the first aspect,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first sun gear and the second sun gear are coupled;
The first carrier and the second ring gear are coupled,
The input shaft is coupled to the second carrier, and the output shaft is coupled to each of the first carrier and the second ring gear;
And the clutch is interposed between the input shaft and the output shaft,
The forward drive brake is interposed between the first sun gear and the second sun gear and the transmission case, and the reverse drive brake is interposed between the first ring gear and the transmission case. It is provided.

Furthermore, the invention according to claim 3 is the power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first carrier and the second ring gear are coupled;
The first ring gear and the second carrier are coupled,
The input shaft is coupled to the first carrier, and the output shaft is coupled to the first ring gear and the second carrier,
And the clutch is interposed between the second carrier and each of the first carrier and the second ring gear,
The forward drive brake is interposed between the first sun gear and the transmission case, and the reverse drive brake is interposed between the second sun gear and the transmission case. Features.

Furthermore, the invention according to claim 4 is the power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first sun gear and the second carrier are coupled;
The first carrier and the second sun gear are coupled,
The input shaft is coupled to each of the first carrier and the second sun gear, and the output shaft is coupled to the second carrier,
And the clutch is interposed between the input shaft and the output shaft,
The forward drive brake is interposed between the first ring gear and the transmission case, and the reverse drive brake is interposed between the second ring gear and the transmission case. Features.

In addition, the invention according to claim 5 is the power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first sun gear and the second ring gear are coupled;
The first carrier and the second sun gear are coupled,
The input shaft is coupled to each of the first carrier and the second sun gear, and the output shaft is coupled to the second carrier,
And the clutch is interposed between the input shaft and the output shaft,
The brake for forward drive is between the first ring gear and the transmission case, and the brake for reverse drive is between the first sun gear and the second ring gear and the transmission case. It is characterized by being interposed.

In addition, the invention according to claim 6 is the power transmission device for a four-wheel drive vehicle according to any one of claims 1 to 5,
A circulating torque detecting means for detecting a circulating torque acting on the driving force transmission system;
When the circulating torque detecting means detects the circulating torque, the transmission mechanism controls the engagement force of one of the clutch and the brake so that the circulating torque is suppressed, and the input shaft and the output It is characterized by controlling the rotation speed ratio of the shaft.

  According to the first aspect of the present invention, the speed change mechanism includes an input shaft coupled to the driving force transmission system on the main driving wheel side, an output shaft coupled to the driving force transmission system on the driven wheel side, The second planetary gear set, one clutch, and a brake for forward driving (in a state where the engine is driving the vehicle) and for reverse driving (in a state where the engine is driven by the inertia traveling of the vehicle). When the clutch is fully engaged, the ratio of the rotational speed of the output shaft to the rotational speed of the input shaft can be established by directly coupling the input shaft and output shaft, or by controlling the fastening force of the clutch and one brake. That is, the gear ratio can be made 1 and can be changed steplessly to the deceleration side or the acceleration side. As a result, it becomes possible to increase or decrease the rotational speed of the driven wheel axle relative to the rotational speed of the main drive wheel axle.

  Further, according to the invention described in claims 2 to 5, it is relatively simple by connecting the input shaft, the output shaft, the two planetary gear sets, the one clutch, and the two brakes according to the relationship described in each claim. Thus, a transmission mechanism for a four-wheel drive vehicle that is compact and excellent in mountability is realized.

  Furthermore, according to claim 6, due to a change in the diameter of either the main drive wheel or the slave drive wheel, the ratio of the peripheral speed of the main drive wheel and the slave drive wheel deviates from the required peripheral speed ratio, and the main drive wheel When the circulating torque is generated in the driving force transmission system between the wheel and the driven wheel, the circulating torque detecting means detects this and the driving force is controlled so that the circulating torque is suppressed based on the detection result. A transmission mechanism provided in the transmission system changes the transmission ratio. As a result, good running performance as a four-wheel drive vehicle is maintained, and problems such as deterioration in engine fuel efficiency due to circulating torque and deterioration in durability of the power transmission system due to heat generation are prevented.

  FIG. 1 schematically shows the configuration of a four-wheel drive vehicle equipped with a power transmission device for a four-wheel drive vehicle according to an embodiment of the present invention.

  The vehicle denoted by reference numeral 10 in FIG. 1 is a four-wheel drive vehicle having front drive wheels 12F and rear drive wheels 12R. The four-wheel drive vehicle 10 includes an engine 14 as a drive source, a transmission 16 for transmitting the output of the engine 14 to the drive wheels 12F and 12R, and a driving force from the transmission 16 to the left and right front drive wheels 12F. The front wheel differential 20 that is transmitted via the rear wheel, the transfer 22 that extracts the driving force transmitted to the rear driving wheel 12R, and the rear wheel wheel 24 that transmits the driving force from the transfer 22 to the left and right rear driving wheels 12R. And a wheel differential 26. In this configuration, the front drive wheel 12F is the main drive wheel, and the rear drive wheel 12R is the slave drive wheel.

  Further, the transfer 22 and the rear wheel differential 26 are drivingly connected via a speed change mechanism 28. Specifically, the other end of the driving force transmission shaft 30 a whose one end is connected to the output shaft of the transfer 22 is connected to the input shaft of the transmission mechanism 28, and the driving force transmission whose one end is connected to the output shaft of the transmission mechanism 28. The other end of the shaft 30b is connected to the input shaft of the rear wheel differential 26.

  The speed change mechanism 28 is configured to be able to change the speed change ratio, that is, the rotation speed ratio of the driving force transmission shafts 30a and 30b. The speed change ratio is a speed change ratio (hereinafter referred to as “required speed change ratio”) required for the ratio of the peripheral speeds of the drive wheels 12F and 12R (speed in the tangential direction on the contact surface) to be a required ratio (required peripheral speed ratio) "). Upon confirmation, the “necessary speed ratio” referred to here is, for example, a speed ratio that makes the required peripheral speed ratio 1: 1, or a speed ratio that makes the required peripheral speed ratio 1: m (m> 1). That is, there is one speed change ratio with respect to the required peripheral speed ratio.

  This will be described with reference to FIG. FIG. 2 schematically shows the four-wheel drive vehicle 10 in operation. The figure shows a case where the peripheral speeds of the drive wheels 12F and 12R are the same speed V corresponding to the vehicle speed during traveling, that is, the required peripheral speed ratio is 1: 1.

  At this time, for example, when the radius of the front drive wheel 12F is r1 and the radius of the rear drive wheel 12R is r2, which is different from r1, the rotational speed VF of the front axle 18 and the rotational speed VR of the rear axle 24 are Ratio (necessary rotational speed ratio = VF: VR) needs to be r2: r1.

  For this purpose, the ratio of the rotational speed VF of the front drive wheel 12F to the rotational speed V1 of the driving force transmission shaft 30a and the ratio of the rotational speed VR of the rear drive wheel 12R to the rotational speed V2 of the driving force transmission shaft 30b are as follows. Assuming that the transmission mechanism 28 is equal, the ratio of the rotational speed V1 of the driving force transmission shaft 30a and the rotational speed V2 of the driving force transmission shaft 32b is r2: r1, that is, the transmission ratio is r1 / r2 (output side It is necessary to maintain the rotation speed V2 / input-side rotation speed V1).

  That is, the necessary speed change ratio in this case is a speed change ratio at which the peripheral speed is the same in each of the drive wheels 12F and 12R. If the diameters r1 and r2 of the front drive wheel 12F and the rear drive wheel 12R are the same, the gear ratio is set to 1: 1.

  From here, a specific configuration of the transmission mechanism 28 shown in FIG. 1 and a method of changing the transmission ratio of the transmission mechanism 28 executed by the control device 34 will be described.

  FIG. 3 is a skeleton diagram of an example transmission mechanism. The speed change mechanism denoted by reference numeral 100 in the figure includes an input shaft (a shaft coupled to the driving force transmission shaft 30a illustrated in FIG. 1) 102, an output shaft (a shaft coupled to the driving force transmission shaft 30b) 104, and two planetary gears. Sets 106 (corresponding to the first planetary gear set forth in claims) and 108 (corresponding to the second planetary gear set forth in claims), one clutch 110, and two brakes 112 (claimed) ) And 114 (corresponding to the reverse driving brake described in the claims).

  The two planetary gear sets 106 and 108 are single pinion type planetary gear sets, which respectively mesh with the sun gears 106s and 108s, the pinions 106p and 108p that mesh with the sun gear, the carriers 106c and 108c that support the pinion, and the pinion. It comprises ring gears 106r and 108r.

  In transmission mechanism 100, sun gear 106s and sun gear 108 are coupled, and carrier 106c and ring gear 108r are coupled. The input shaft 102 is coupled to the carrier 108c, and the output shaft 104 is coupled to the carrier 106c and the ring gear 108r.

  Further, a clutch 110 is interposed between the input shaft 102 and the output shaft 104. Furthermore, a forward drive brake 112 is provided between the sun gear 106 s and the sun gear 108 s and the transmission case 116 of the transmission mechanism 100, and a reverse drive brake 114 is provided between the ring gear 106 r and the transmission case 116. It is installed.

  According to the speed change mechanism 100 having such a configuration, the speed change mechanism 100 continuously changes the speed ratio to the speed increasing side and the speed reducing side by controlling the fastening force of the clutch 110 and the two brakes 112 and 114. Is possible.

  Specifically, the speed change mechanism 100 changes its speed ratio by the control device 34 of FIG. 1 controlling the clutch 110 and the two brakes 112 and 114.

  For example, when a change to the gear ratio 1 is requested, the control device 34 controls the clutch 110 to a fully engaged state, directly connects the input shaft 102 and the output shaft 104, and disengages the two brakes 112 and 114. Control to the state.

  Further, when a change to a gear ratio other than 1 is requested, the control device 34 determines whether the clutches 110 and 2 are based on the transmission direction of the drive torque transmitted by the transmission mechanism 100 and the requested gear ratio value. The fastening force of the two brakes 112 and 114 is controlled.

  More specifically, as shown in FIG. 4, there are four types of control of the fastening force of the clutch 110 and the two brakes 112 and 114 of the speed change mechanism 100 executed by the control device 34. The example described here is an example in which the front wheel 12F and the rear wheel 12R have the same diameter r.

  In the control (a), when the speed change mechanism 28 (100) is transmitting the driving torque output from the engine 14 to the rear wheel 12R, the driving force transmission shaft 30a (input shaft 102) is driven with respect to the rotational speed V1. The control for reducing the rotational speed V2 of the force transmission shaft 30b (output shaft 104) is shown. Here, the direction in which the driving torque output from the engine is transmitted to the rear wheel 12R is defined as the forward direction, and the opposite direction is defined as the reverse direction.

  Further, the control (b) is such that when the speed change mechanism 28 (100) is transmitting the driving torque output from the engine 14 to the rear wheel 12R, the rotational speed V1 of the driving force transmission shaft 30a (input shaft 102). Control for increasing the rotational speed V2 of the driving force transmission shaft 30b (output shaft 104) is shown.

  Further, the control (c) is performed when the transmission mechanism 28 (100) transmits the driving torque output from the rear wheels 12R to the engine 14 (when the vehicle is in a coasting state). The control for decelerating the rotational speed V2 of the driving force transmission shaft 30b (output shaft 104) with respect to the rotational speed V1 of the shaft 30a (input shaft 102) is shown.

  Furthermore, the control (d) is performed when the transmission mechanism 28 (100) is transmitting the driving torque output from the rear wheel 12R to the engine 14 (when the vehicle is in a coasting state). The control for increasing the rotational speed V2 of the driving force transmission shaft 30b (output shaft 104) with respect to the rotational speed V1 of the transmission shaft 30a (input shaft 102) is shown.

  Note that the direction of the drive torque transmitted by the speed change mechanism can be determined by, for example, an accelerator pedal sensor that detects whether or not the accelerator pedal is depressed. In other words, when the accelerator pedal is depressed, the engine outputs drive torque, so the direction of the drive torque transmitted by the speed change mechanism is the positive direction. Otherwise, it is the reverse direction.

  In the case of control (a) (when the drive torque is in the positive direction and deceleration is required), the control device 34, as shown in the table of FIG. The reverse drive brake 114 is not controlled (not controlled).

  Referring to FIG. 3, the control device 34 controls the engagement force of the clutch 110 to be small, and sets the transmission gear ratio of the transmission mechanism 100 to the requested transmission gear ratio on the deceleration side. As a result, the torque transmitted to the rear wheel 12R is reduced and the rotation thereof is decelerated.

  However, if the clutch 110 is only controlled to have a small engagement force, the gear ratio continues to change further to the deceleration side than the requested gear ratio, and the rotation of the rear wheel 12R continues to decelerate.

  As a countermeasure, the control device 34 controls the fastening force of the brake 112 for positive driving. This will be described with reference to a velocity diagram shown in FIG.

This speed diagram shows the rotational speeds of the rotating elements of the two planetary gear sets 106 and 108, that is, the sun gears 106s and 108s, the carriers 106c and 108c, and the ring gears 106r and 108r in the vertical direction. Are shown corresponding to the reciprocals of the number of teeth Zs (106), Zs (108), Zr (106), Zr (108) of the sun gears 106s, 108s and the ring gears 106r, 108r.

  As shown in FIG. 6A, the ratio of the rotational speed of the output shaft 104 to the rotational speed of the input shaft 102, that is, the required speed ratio Rout1 on the speed reduction side (speed reduction side compared to before the speed ratio change). / Rin1 is controlled so that the rotational speed of the sun gears 106s and 108s becomes R1 based on the speed diagram (that is, based on the number of teeth of the sun gears 106s and 108s and the ring gears 106r and 108r). The fastening force of the driving brake 112 is controlled.

  In summary, in the case of control (a), the control device 34 first reduces the engagement force of the clutch 110 to reduce the speed ratio of the speed change mechanism 100 to the required speed ratio Rout1 / Rin1, and rotates the sun gears 106s and 108s. The fastening force of the brake 112 for positive driving is controlled so that the speed becomes R1 for maintaining the required speed ratio Rout1 / Rin1.

  FIG. 6B shows the torque that transmits each component of the speed change mechanism 100 in this case. In the figure, the thick line indicates that torque is transmitted, and the white arrow indicates the direction of torque. Moreover, the friction element shown by a dotted line has shown that it is a slip state.

  First, the torque transmitted through the input shaft 102 is branched and input to the clutch 110 and the carrier 108c. The torque that the clutch 110 transmits from the input shaft 102 side to the output shaft 104 side is smaller than that before the change because the engagement force is changed to the required gear ratio. Torque input to the carrier 108 c is transmitted to the brake 112 for positive driving via the sun gear 108 s and to the output shaft 104 via the ring gear 108. Torque obtained by joining the torque via the clutch 110 and the torque via the ring gear 108r is transmitted to the output shaft 104. As a result, the torque transmitted to the output shaft 104 as a result is substantially the same as before the change to the required gear ratio.

  Further, in the case of the control (b) (when the driving torque is in the positive direction and the speed increase is required), the control device 34, as shown in the table of FIG. The reverse drive brake 114 is not controlled (non-control).

  Specifically, the control device 34 controls the engagement force of the brake 112 for positive driving by controlling the engagement force of the clutch 110 to be small. This is the same as the case of the control (a), but differs in that the fastening force of the brake 112 for positive driving is increased (brake hard) compared to the control (a).

  This will be described with reference to the velocity diagram shown in FIG. The control device 34 controls the rotational speeds of the sun gears 106s and 108s in order to maintain the speed ratio at the requested speed ratio Rout2 / Rin2 on the speed increase side (speed increase side compared to before the speed ratio change) (a ) In the case of R) (see FIG. 6). That is, in the case of the control (b), it is necessary to increase the fastening force of the brake 112 for positive driving compared to the control (a).

  In summary, in the case of control (b), the control device 34 first reduces the engagement force of the clutch 110 to increase the speed ratio of the speed change mechanism 100 to the required speed ratio Rout2 / Rin2, and the sun gears 106s and 108s. The brake for positive driving 112 is set to a larger engagement force than the engagement force at the time of control (a) so that the rotation speed becomes R2 smaller than R1 for maintaining the requested gear ratio Rout2 / Rin2. Control.

  FIG. 7B shows torque that transmits each component of the speed change mechanism 100 in this case.

  Unlike the control (a), the torque transmitted through the input shaft 102 is input only to the carrier 108c. This is because torque is transmitted from the clutch 110 to the input shaft 102 because the output shaft 104 side of the clutch 110 is accelerated compared to the input shaft 102 side. Therefore, the torque from the input shaft 102 and the torque from the clutch 110 are input to the carrier 108c. Torque input to the carrier 108c is transmitted to the brake 112 for positive driving via the sun gear 108s and to the output shaft 104 via the ring gear 108r. Torque from the ring gear 108r branches to the output shaft 104 and the clutch 110. As a result, the torque transmitted to the output shaft 104 as a result is substantially the same as before the change to the required gear ratio.

Further, in the case of control (c) (when the drive torque is in the reverse direction and deceleration is required), the control device 34, as shown in the table of FIG. The fastening force is controlled and the positive drive brake 112 is not controlled (non-control).

  Specifically, the control device 34 controls the engagement force of the reverse drive brake 114 by controlling the engagement force of the clutch 110 to be small.

  This will be described with reference to a velocity diagram shown in FIG. In the case of the control (c), the control device 34 first reduces the engagement force of the clutch 110 to reduce the speed ratio of the speed change mechanism 100 to the required speed ratio Rout3 / Rin3, and the rotational speed of the ring gear 106r is the speed ratio. The fastening force of the reverse drive brake 114 is controlled so as to be R3 for maintaining Rout3 / Rin3.

  FIG. 8B shows torque that transmits each component of the speed change mechanism 100 in this case.

  Torque transmitted through the output shaft 104 is input to the ring gear 108r and the carrier 106c. The torque from the clutch 110 is also input to the ring gear 108r and the carrier 106c. The torque input to the carrier 106c is transmitted to the reverse drive brake 114 via the ring gear 106r and also input to the sun gear 108s via the sun gear 106s. Torque is transmitted to the carrier 108c from the ring gear 108r and the sun gear 108s, and the torque branches to the input shaft 102 and the clutch 110. As a result, the torque transmitted to the input shaft 102 is substantially the same as before the change to the required gear ratio.

  Furthermore, in the case of the control (d) (when the driving torque is in the reverse direction and a speed increase is required), the control device 34, as shown in the table of FIG. The fastening force of 114 is controlled, and the brake 112 for positive driving is not controlled (non-control).

  Specifically, the control device 34 controls the engagement force of the reverse drive brake 114 by controlling the engagement force of the clutch 110 to be small. This is the same as in the control (c), but differs in that the fastening force of the reverse drive brake 114 is made smaller (weakly braked) than in the control (c).

  This will be described with reference to a velocity diagram shown in FIG. In order to maintain the gear ratio at the requested gear ratio Rout4 / Rin4 on the speed increasing side (speed increasing side compared to before the gear ratio change), the control device 34 controls the rotational speed of the ring gear 106r in the control (c). It is necessary to make it larger than R3 in the case (see FIG. 8). That is, in the case of the control (d), it is necessary to make the fastening force of the reverse drive brake 114 smaller than that in the control (c).

  In summary, in the case of control (d), the control device 34 first reduces the engagement force of the clutch 110 to increase the speed ratio of the speed change mechanism 100 to the required speed ratio Rout4 / Rin4, and the rotational speed of the ring gear 106r. However, the reverse drive brake 114 is controlled to be smaller than the engagement force at the time of control (c) so that R4 is larger than R3 for maintaining the requested gear ratio Rout4 / Rin4. .

  FIG. 9B shows torque that transmits each component of the speed change mechanism 100 in this case.

  Torque transmitted through the output shaft 104 is input to the ring gear 108r and the carrier 106c and is transmitted to the clutch 110. The torque transmitted to the clutch 110 is transmitted to the input shaft 102. The torque input to the carrier 106c is transmitted to the reverse drive brake 114 via the ring gear 106r and also input to the sun gear 108s via the sun gear 106s. Torque is transmitted to the carrier 108c from the ring gear 108r and the sun gear 108s, and the torque is transmitted to the input shaft 102. As a result, the torque from the carrier 108c and the torque from the clutch 110 are transmitted to the input shaft 102, and the torque is substantially the same as before the change to the required gear ratio.

  According to the above-described configuration, the transmission mechanism 100 having a relatively simple configuration including the input shaft 102, the output shaft 104, the two planetary gear sets 106 and 108, the one clutch 110, and the two brakes 112 and 114 is obtained. Accordingly, a power transmission device for a four-wheel drive vehicle that is compact and excellent in mountability is realized. Further, the control device 34 can completely engage the clutch 110 to set the transmission gear ratio of the transmission mechanism 100 to 1 and control the engagement force of one of the clutch 110 and the brakes 112 and 114 to reduce the speed or The gear ratio can be changed steplessly on the speed increasing side.

  Thereby, for example, when the vehicle turns, the speed change mechanism 100 increases the rotational speed of the rear wheel 12R (axle 24) with respect to the rotational speed of the front wheel 12F (axle 18), whereby the vehicle is oversteered and turns. Will improve. In this case, the turning of the vehicle can be detected by a sensor that detects the steering angle of the steering, for example.

  Further, for example, when a circulating torque from the front wheel 12F side to the rear wheel 12R side is generated due to a decrease in the diameter of the rear wheel 12R, the speed change mechanism 100 causes the rear wheel 12R (the axle 18) to rotate with respect to the rotational speed. The circulating torque can be suppressed by increasing the rotational speed of the axle 24).

  On the other hand, for example, when a circulating torque is generated from the rear wheel 12R side to the front wheel 12F side due to a decrease in the diameter of the front wheel 12F, the speed change mechanism 100 causes the rear wheel 12R (axle axle) relative to the rotational speed of the front wheel 12F (axle 18). The circulating torque can be suppressed by decelerating the rotational speed of 24).

  In addition, whether or not the circulating torque is generated, and when it is generated, the magnitude and direction thereof are, for example, torque generated in the driving force transmission shaft 30a coupled to the input shaft 102 of the speed change mechanism 100. Can be obtained, for example, by detecting with a torque sensor.

  More specifically, the driving torque based on the torque from the engine 14 transmitted to the driving force transmission shaft 30b is calculated with reference to FIG. This drive torque is determined by calculating the engine output torque from the engine speed and engine load and a pre-stored engine characteristic map. The torque is determined based on the current gear ratio of the transmission 16 and the rear side by the transfer 22. It is obtained by integrating the torque division ratio toward the drive wheel 12R.

  A driving torque based on the torque from the engine 14 transmitted to the driving force transmission shaft 30b calculated above is subtracted from the torque detected by the torque sensor generated in the driving force transmission shaft 30a. In this case, if no circulating torque is generated in the driving force transmission system, the difference is zero. However, if the circulating torque is generated, the magnitude is calculated including the direction. .

  Since the circulating torque generated when the speed change mechanism 100 is accelerated or decelerated can be suppressed, good running performance as a four-wheel drive vehicle is maintained, and deterioration of engine fuel consumption performance caused by the circulating torque is reduced. Problems such as deterioration of the durability of the power transmission system due to heat generation are prevented.

  Although the present invention has been described with the embodiment, the present invention is not limited to this.

  For example, even with a speed change mechanism other than the speed change mechanism 100 described above, it is possible to obtain the same effect as the speed change mechanism 100 described above.

  The speed change mechanisms 200, 300, and 400 shown in the skeleton diagram in FIGS. 10 to 12 are similar to the speed change mechanism 100 described above, and input shafts 202, 302, and 402 are connected to the driving force transmission shaft 30a shown in FIG. , Output shafts (shafts coupled to the driving force transmission shaft 30b) 204, 304, 404, two planetary gear sets 206, 306, 406 (corresponding to the first planetary gear set forth in the claims) and 208, 308, 408 (corresponding to the second planetary gear described in the claims), one clutch 210, 310, 410 and two brakes 212, 312, 412 (corresponding to the positive drive brake described in the claims) .) And 214, 314, 414 (corresponding to the reverse drive brake described in the claims).

  In each speed change mechanism, the two planetary gear sets 206, 306, 406 and 208, 308, 408 are single pinion type planetary gear sets, which mesh with the sun gears 206s, 306s, 406s and 208s, 308s, 408s, respectively. Pinions 206p, 306p, 406p and 208p, 308p, 408p, carriers 206c, 306c, 406c and 208c, 308c, 408c supporting the pinion, and ring gears 206r, 306r, 406r and 208r, 308r, 408r meshing with the pinion Consists of

  As shown in FIG. 10, in the speed change mechanism 200, the carrier 206c and the ring gear 208r are coupled, the ring gear 206r and the carrier 208c are coupled, the input shaft 202 is coupled to the carrier 206c, the output shaft 204 is coupled to the ring gear 206r, and Coupled to each of the carriers 208c. A clutch 210 is interposed between the carrier 208c, the carrier 206c, and the ring gear 208r. A positive drive brake 212 is provided between the sun gear 206s and the transmission case 216, and the sun gear 208s and the transmission case 214 are connected. Between these, a brake 214 for reverse driving is interposed.

  11, in the speed change mechanism 300, the sun gear 306s and the carrier 308c are coupled, the carrier 306c and the sun gear 308s are coupled, and the input shaft 302 outputs to the carrier 306c and the sun gear 308s, respectively. Shaft 304 is coupled to carrier 308c. A clutch 310 is interposed between the input shaft 302 and the output shaft 304, and a brake 312 for positive drive is provided between the ring gear 306 r and the transmission case 316, and between the ring gear 308 r and the transmission case 316. Is provided with a brake 314 for reverse driving.

  Further, as shown in FIG. 12, in the transmission 400, the sun gear 406s and the ring gear 408r are coupled, the carrier 406c and the sun gear 408s are coupled, and the input shaft 402 is connected to the carrier 406c and the sun gear 408s, respectively. 404 is coupled to carrier 408c. Further, a clutch 410 is interposed between the input shaft 402 and the output shaft 404, and a brake 412 for positive drive is provided between the ring gear 406r and the transmission case 416, and the transmission gear case with the sun gear 406s and the ring gear 408r, respectively. Brake 414 for reverse driving is interposed between 416 and 416.

FIG. 13 is a table showing the control contents of the control device corresponding to each control (direction of driving torque, request for changing the transmission ratio) shown in FIG. 4 performed on these transmission mechanisms 200, 300, and 400. Show.

  As shown in FIG. 13, in the case of the control (a), the transmission gear ratios of the transmission mechanisms 200, 300, and 400 are changed to values on the deceleration side (deceleration side compared to before the transmission gear ratio change). The fastening force of 310, 410 is controlled to be small, and the positive drive brakes 212, 312, 412 are set to a small fastening force (weak brake).

  In the case of the control (b), the gear ratios of the speed change mechanisms 200, 300, and 400 are changed to values on the speed increasing side (speed increasing side compared to before changing the speed ratio). Thus, the positive driving brakes 212, 312, and 412 are set to a larger fastening force than the control (a) (strong braking).

  Further, in the case of the control (c), the transmission gear ratios of the transmission mechanisms 200, 300, and 400 are changed to values on the deceleration side (deceleration side compared to before the transmission gear ratio change), and for this reason, the clutches 210, 310, and 410 are engaged. The force is controlled to be small, and the reverse driving brakes 214, 314, and 414 are set to a large fastening force (strong braking).

  Furthermore, in the case of the control (d), the speed ratio of the speed change mechanisms 200, 300, 400 is changed to a value on the speed increasing side (speed increasing side as compared to before the speed ratio change). The fastening force of 410 is controlled to be small, and the reverse driving brakes 214, 314, and 414 are set to a fastening force that is smaller than the control (c) (weak brake).

  As described above, according to the present invention, it is possible to increase or decrease the rotation speed of the driven wheel relative to the rotation speed of the main drive wheel, so that the effects of improving the turning performance and suppressing the circulating torque are expected. Therefore, there is a possibility of being suitably used in the field of manufacturing industries of four-wheel drive vehicles.

1 is a diagram schematically showing a configuration of a four-wheel drive vehicle including a power transmission device for a four-wheel drive vehicle according to an embodiment of the present invention. FIG. 1 is a perspective view schematically showing a four-wheel drive vehicle that is running. FIG. FIG. 2 is a schematic diagram of a speed change mechanism as an example of a speed change mechanism shown in FIG. 1. It is a figure for demonstrating several control (a)-(d) which a control apparatus performs. It is a figure which shows the table | surface of the control content of several control (a)-(d). The speed diagram of control (a) and the flow of torque are shown. The speed diagram of control (b) and the flow of torque are shown. The speed diagram of control (c) and the flow of torque are shown. The speed diagram of control (d) and the flow of torque are shown. FIG. 5 is a schematic diagram of a speed change mechanism of another example of the speed change mechanism shown in FIG. 1. FIG. 5 is a skeleton diagram of another speed change mechanism of the speed change mechanism shown in FIG. 1. FIG. 5 is a skeleton diagram of a speed change mechanism of still another example of the speed change mechanism shown in FIG. 1. It is a figure which shows the table | surface of the control content with several control (a)-(d) with respect to the transmission mechanism shown in FIG.10, FIG11 and FIG.12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Transmission mechanism 102 Input shaft 104 Output shaft 106 1st planetary gear set 108 2nd planetary gear set 110 Clutch 112 Brake for forward drive 114 Brake for reverse drive

Claims (6)

Provided in a drive source, a transfer device that distributes and transmits the output of the drive source to the main drive wheel axle and the slave drive wheel axle, and a drive force transmission system between the main drive wheel axle and the slave drive wheel axle A power transmission device for a four-wheel drive vehicle having a speed change mechanism,
The transmission mechanism includes an input shaft coupled to a driving force transmission system on the main drive wheel side, an output shaft coupled to a driving force transmission system on the slave drive wheel side, first and second planetary gear sets, A clutch for forward driving and a brake for reverse driving, and the clutch is completely engaged to directly connect the input shaft and the output shaft, and the engagement force of one of the clutch and the brake is A power transmission device for a four-wheel drive vehicle, characterized in that the rotational speed ratio between the input shaft and the output shaft is controlled. The power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first sun gear and the second sun gear are coupled;
The first carrier and the second ring gear are coupled,
The input shaft is coupled to the second carrier, and the output shaft is coupled to each of the first carrier and the second ring gear;
And the clutch is interposed between the input shaft and the output shaft,
The forward drive brake is interposed between the first sun gear and the second sun gear and the transmission case, and the reverse drive brake is interposed between the first ring gear and the transmission case. A power transmission device for a four-wheel drive vehicle. The power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first carrier and the second ring gear are coupled;
The first ring gear and the second carrier are coupled,
The input shaft is coupled to the first carrier, and the output shaft is coupled to the first ring gear and the second carrier,
And the clutch is interposed between the second carrier and each of the first carrier and the second ring gear,
The forward drive brake is interposed between the first sun gear and the transmission case, and the reverse drive brake is interposed between the second sun gear and the transmission case. A power transmission device for a four-wheel drive vehicle. The power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first sun gear and the second carrier are coupled;
The first carrier and the second sun gear are coupled,
The input shaft is coupled to each of the first carrier and the second sun gear, and the output shaft is coupled to the second carrier,
And the clutch is interposed between the input shaft and the output shaft,
The forward drive brake is interposed between the first ring gear and the transmission case, and the reverse drive brake is interposed between the second ring gear and the transmission case. A power transmission device for a four-wheel drive vehicle. The power transmission device for a four-wheel drive vehicle according to claim 1,
The first planetary gear set has a first sun gear, a first carrier, and a first ring gear;
The second planetary gear set has a second sun gear, a second carrier, and a second ring gear;
The first sun gear and the second ring gear are coupled;
The first carrier and the second sun gear are coupled,
The input shaft is coupled to each of the first carrier and the second sun gear, and the output shaft is coupled to the second carrier,
And the clutch is interposed between the input shaft and the output shaft,
The brake for forward drive is between the first ring gear and the transmission case, and the brake for reverse drive is between the first sun gear and the second ring gear and the transmission case. A power transmission device for a four-wheel drive vehicle characterized by being interposed. In the power transmission device of the four-wheel drive vehicle according to any one of claims 1 to 5,
A circulating torque detecting means for detecting a circulating torque acting on the driving force transmission system;
When the circulating torque detecting means detects the circulating torque, the transmission mechanism controls the engagement force of one of the clutch and the brake so that the circulating torque is suppressed, and the input shaft and the output A power transmission device for a four-wheel drive vehicle, characterized by controlling a rotation speed ratio of a shaft.

Images