JP4527372B2 - Hydraulic power transmission device - Google Patents

Description

The present invention relates to a hydraulic power transmission device that is incorporated in a rear differential of a four-wheel drive vehicle and distributes torque according to a rotational difference between front and rear wheels and left and right wheels.

  An FF type four-wheel drive vehicle equipped with a conventional power transmission device is shown in FIG. In FIG. 7, the power from the engine 100 is transmitted to the left and right front wheels 106 and 108, and from the propeller shaft 102 to the left and right rear wheels 112 and 114 via a hydraulic power transmission device 110 known as a twin coupling type. Communicated.

  FIG. 8 shows a hydraulic circuit of a conventional twin coupling type hydraulic power transmission device 110. In FIG. 8, the twin coupling type hydraulic power transmission device 110 includes couplings 116 and 118 on the left and right. The couplings 116 and 118 include a right cam 120 and a left cam 122, form a pair of cam surfaces 120a and 122a having two or more peaks on the inner surface, and are fixed to the housing on the propeller shaft 102 side.

  Two or more pistons 124, 126 are arranged for the cam 120 and the cam 122, and the piston chambers 128, 130 are connected to the axle shaft side of the left and right rear wheels. A suction check valve 132 and a discharge check valve 134 are provided for the left and right piston chambers 128, 130, and are connected in common by the suction communication passage 136 and the discharge communication passage 138, respectively, and between the suction communication passage 136 and the discharge communication passage 138. Is provided with an orifice 140.

  The operation of this hydraulic power transmission device is as follows. As shown in FIG. 9A, if the front wheels 106 and 108 slip on the low μ road surface 142, a difference in rotation occurs between the rear wheels 112 and 114, and the hydraulic power transmission device 110 is shown in FIG. The left and right couplings 116 and 118 are operated, and torques corresponding to the rotation differences are generated on the left and right rear wheels 112 and 114, respectively.

  Further, as shown in FIG. 9B, if the front wheels 106 and 108 are slipped on the low μ road surface 142 and the right rear wheel 114 is slipped on the low μ road surface 144 at the same time, the hydraulic power transmission device 110 is connected to the left side of FIG. Only the coupling 118 is operated, and torque corresponding to the rotation difference is generated in the left rear wheel 112.

  For example, when the couplings 116 and 118 on both sides in the hydraulic power transmission device 110 of FIG. 8 are operated as shown in FIG. 9A, taking the operation of the right coupling 116 as an example, the upper piston 124 is camped. Pushed to the left by the crest 120a, the oil is discharged from the piston chamber 128 by opening the discharge check valve 134 and discharged. At the same time, the lower piston 124 is pushed back to the right along the cam crest 120a, thereby opening the suction check valve 132. Then, the oil is sucked into the piston chamber 128, whereby a high pressure corresponding to the difference in rotational speed is generated by the resistance of the oil passing through the orifice 140, and torque is generated in the right rear wheel 114.

  At the same time, the left coupling 118 operates in the same manner, thereby generating a high pressure corresponding to the rotational speed difference due to the resistance of the oil passing through the orifice 140, thereby generating torque on the left rear wheel 112.

  Here, assuming that the flow rate of oil passing through the orifice 140 is Q and the torque is T, when the left and right couplings 116 and 118 are operated, the following relational expression exists between them.

T = f (Q ² )
Therefore, as shown in FIG. 9A, the torque characteristic with respect to the differential rotation when the left and right couplings 116 and 118 are operated is the square of the flow rate Q, that is, the differential rotation as in the torque characteristic 146 of FIG. The relationship increases in proportion to the square of.

On the other hand, as shown in FIG. 9B, when only one side of the coupling 118 is operated, the flow rate is ½ when the both sides are operated and the torque per piston is t. The number of pistons is also halved. For this reason, the torque _TL during left side operation is
T _L = T × (1/2) × (1/2) ² = T × (1/8)
It becomes. That is, the torque during one-side operation is a torque characteristic 148 in which the torque is ８ with respect to the torque characteristic 146 with respect to the differential rotation during both-side operation in FIG.
JP-A-5-047442

  However, the torque characteristics of such a conventional twin coupling type hydraulic power transmission device are fixedly determined by the flow rate of the orifice 140 during both-side operation and one-side operation. If the orifice is determined so as to optimize the torque characteristic, the torque characteristic at the time of one-side operation is reduced to 1/8, and the torque is too low, so that the vehicle running performance, that is, the diagonal stack escape performance is low. On the other hand, if the orifice is determined so that the torque characteristic during one-side operation is optimal, the torque during two-side operation becomes too high, causing problems in coupling strength and performance.

The present invention has been made in view of such a conventional problem, and is a hydraulic power that can improve the running performance of a vehicle by making it possible to individually set the torque generated during both-side operation and one-side operation. The object is to provide a transmission device.

In order to achieve this object, the present invention is configured as follows. Hydraulic power transmission device of the present invention is provided between relatively rotatable three axes with each other is connected to the first shaft to form a cam surface of the pair having two or more peaks in both inner side surfaces, the internal Is connected to the housing serving as the low pressure chamber , the second shaft and the third shaft, and is housed in the housing so as to be rotatable and opposed to each other, and a plurality of piston chambers are formed in the axial direction with respect to the cam surface. Each of the pair of rotors and the plurality of piston chambers is reciprocally accommodated by receiving a return spring and is moved by a cam surface during relative rotation between the first and second or first and third shafts. A plurality of pistons to be driven, a plurality of suction check valves that are provided in suction ports that pass through the pistons and communicate with the piston chambers from the low pressure chambers outside the piston chambers, and are opened only when the pistons are retracted; Penetrates the piston chamber Communicating provided a discharge port communicating from the piston chamber to the outside of the piston chamber and a plurality of discharge check valve for discharging oil to open only during advancement of the piston, the discharge port of the plurality of discharge check valve to the low pressure chamber And a block member disposed between a pair of rotors having a first orifice disposed in the discharge communication passage and fixed to the housing, and a first shaft, a second shaft, and a third shaft In the hydraulic power transmission device for transmitting torque according to the difference in rotational speed between each of the communication paths from the discharge ports of the pair of rotors upstream of the first orifice provided in the discharge communication path of the block member The second and third orifices having an opening area smaller than that of the first orifice are provided.

Here, if the opening area of the second orifice and the third orifice is the same A2, and the opening area of the first orifice is A1, the opening area of each of the second and third orifices is larger than each opening area A2 of the second and third orifices. Less than the area, that is, A2 <A1 <(2 × A2)
It is characterized by that.

  In the hydraulic power transmission device of the present invention, when the piston is pushed in by the cam surface and the pushed-out oil passes through the orifice, the oil pressure in the piston chamber rises due to the resistance of the orifice, and a reaction force is generated in the piston. Torque is generated by rotating a housing having a cam surface against the piston reaction force. This torque is proportional to the square of the orifice passing flow rate Q, that is, the square of the differential rotation.

  For this reason, when the couplings on both sides are activated, a torque proportional to the square of the passing flow rate Q is generated in the left and right rear wheels depending on the resistance of the first orifice, but only the coupling on one side is activated. In this case, a torque proportional to the square of the passing flow rate Q is generated in the left rear wheel or the right rear wheel depending not only on the first orifice but only on the resistance of the second orifice.

As a result, the relationship between the orifice and torque characteristics during both-side operation and one-side operation of a pair of couplings can be individually set by the first orifice and the second orifice, and when a single orifice is provided, There is no restriction that the torque characteristic at the time of one-side operation is fixed to a relationship of 8: 1 with respect to the torque characteristic, and the degree of freedom in design is increased, and the generated torque at the time of both-side operation and one-side operation is optimized, Runability can be improved.

  FIG. 1 is a cross-sectional view showing an embodiment of a hydraulic power transmission device according to the present invention. In FIG. 1, a hydraulic power transmission device 10 of the present invention has a differential case 12 that functions as a housing. The differential case 12 has a cylindrical shape that is open to the left and right, and a pair of couplings on the left and right with respect to a central block member 68. (Hydraulic power transmission joint) is incorporated.

  That is, the right cam 14 and the left cam 16 are fixed to the left and right sides of the differential case 12, and the right cam 14 and the left cam 16 form cam surfaces 18 and 20 on the inner surfaces.

  FIG. 2 shows a left side view and an inner perspective view of the left cam 16 shown in FIG. In the left cam 16 of FIG. 2, a cam surface 20 is formed on the inner surface, and a through hole 29 for supporting the rotor is provided in the central portion. The cam surface 20 of the left cam 16 forms, for example, four cam peaks in this example, and there are nine pistons to be driven. The number of cam ridges and the number of pistons can be appropriately determined as necessary.

  Referring again to FIG. 1, following the right cam 14 and the left cam 16, a right rotor 22 and a left rotor 24 are rotatably incorporated inside thereof. The right rotor 22 and the left rotor 24 are formed with piston chambers 30 and 32 that are open to the outside. The pistons 34 and 36 are slidably incorporated in the piston chambers 30 and 32, and the center of the right rotor 22 and the left rotor 24. The part is provided with connecting holes 26 and 28 for connecting the axle shafts of the left and right wheels respectively by splines.

  Balls 38 and 40 are interposed between the pistons 34 and 36, the cam surfaces 18 and 20 of the right cam 14 and the left cam 16, and the right rotor 22 and the left rotor 24 are smoothly opposed to the cam surfaces 18 and 20. It can be rotated. Return springs 40 and 42 are incorporated in the piston chambers 30 and 32, and the pistons 34 and 36 are pressed against the cam surfaces 18 and 20 via the balls 38 and 40.

  The pistons 34, 36 are provided with suction grooves 44, 46 communicating with the low pressure chamber 75 inside the differential case 12, and suction ports 48, 50 are provided through the pistons 34, 36 from the suction groove 44. Yes. The intake check valves 52 and 54 are incorporated in the intake ports 48 and 50, respectively. The flow path is opened when the pistons 34 and 36 move toward the cam surfaces 18 and 20, and the pressure from the low pressure chamber 75 is increased. Oil flows into the piston chambers 30 and 32.

  Discharge ports 56 and 58 are provided on the central block member 68 side of the piston chambers 30 and 32, and discharge check valves 60 and 62 are provided in the discharge ports 56 and 58, respectively. The discharge check valves 60 and 62 are opened when the pistons 34 and 36 are pushed forward by the cam surfaces 18 and 20 via the balls 38 and 40 by the cam surfaces 18 and 20, and the oil from the piston chambers 30 and 32 is supplied to the valve plates 64 and 64. The passage 66 is discharged from the communication passages 70 and 72 of the block member 68 to the low pressure chamber 75 of the differential case 12.

  Valve plates 64 and 66 are disposed between the right rotor 22 and the left rotor 24 and the central block member 68, and the valve plates 64 and 66 are fixed to the right rotor 22 and the left rotor 24 by pins, respectively.

  FIG. 3 shows the valve plate 66 provided on the left rotor 24 side in FIG. 1, and FIG. 3 (A) shows its right end face and FIG. 3 (B) shows its left end face. In this valve plate 66, a communication groove 84 that communicates the opening position of the discharge port 58 provided with the discharge check valve 62 provided on the end face of the left rotor 24 is formed in a ring shape. A communication hole is provided at a location, and a third orifice 78, which will be clarified later, is formed here. Sliding surfaces 88a, 88b, 88c, 88d are formed on the end surface of the valve plate 66 on the left rotor 24 side.

  Further, sliding contact surfaces 86a, 86b, 86c are formed on the end surface of the valve plate 66 on the block member 68 side in FIG. The pin holes 90 and 91 are used for driving a pin for positioning and fixing to the left rotor 24. The structure of the valve plate 66 is the same for the valve plate 64 provided for the right rotor 22 in FIG.

  4 is a cross-sectional view of the block member 68 fixed to the center of the differential case 12 of FIG. The block member 68 includes a communication groove 84 that allows the openings of the second orifice 76 and the third orifice 78 provided in the valve plates 64 and 66 located on both sides to communicate with each other, and communicates with the communication groove 84. The communication passage 70 is penetrated inside, and the communication passage 72 is opened from the orthogonal outer peripheral direction at a substantially center of the communication passage 70, and a first orifice 74 is formed at this connection portion.

  Further, the block member 68 has notches 82 formed in two places on the left and right sides, and a projection 80 on the inner side of the differential case 12 is fitted and fixed thereto. Further, a communication hole 85 is formed from the inside of the block member 68 toward the outer peripheral portion, and the low pressure chamber 75 on the outer peripheral side communicates with the internal accumulator chamber 87.

  Referring again to FIG. 1, an accumulator chamber 87 is formed by an accumulator piston 94 and a return spring 96 at the center of the block member 68, and the volume of the low-pressure chamber is varied according to the volume expansion of oil accompanying a temperature change. The pressure on the low pressure side can always be adjusted to the spring adjustment pressure.

Here, the opening area of the first orifice 74 provided in the block member 68 of FIG. 1 is A1, and the opening areas of the second orifice 76 and the third orifice 78 provided in the left and right valve plates 64 and 66 are A2 respectively. Then, each opening area A2 of the second and third orifices 76 and 78 is made smaller than the opening area A1 of the first orifice 74. Specifically, the opening area A1 of the first orifice 74 is set to be larger than each opening area A2 of the second and third orifices 76 and 78 and smaller than (2 × A2) which is the total area. That is
A2 <A1 <(2 × A2)
Is set to be a relationship.

  FIG. 5 shows a hydraulic circuit of the hydraulic power transmission device according to the embodiment of FIG. 1. Of the right coupling 10 </ b> R and the left coupling 10 </ b> L provided as a twin coupling, a differential rotation is performed in the right coupling 10 </ b> R. Takes an example when the operation occurs. When only the right coupling 10R is operated, the front wheel side and the right rear wheel side slip on the low μ road surface, and the right cam 14 side of the right coupling 10R, that is, the right rear wheel with respect to the differential case 12 and the left coupling 10L. This is when differential rotation occurs on the side.

  Thus, when only the right coupling 10R is operated, the right rotor 22 side incorporating the piston 34 relative to the right cam 14 fixed to the differential case 12 side causes relative rotation, and the movement of the cam surface 18 causes the lower piston to move downward. 34 reverses and opens the intake check valve 52, and sucks oil from the low pressure chamber 75 into the piston chamber 30.

  At the same time, the upper piston 34 moves forward by the cam surface 18 and compresses the oil in the piston chamber 30, thereby opening the discharge check valve 60 and forming the second orifice 76, the communication path 70, the first orifice 74, and the communication path 72. Oil flows into the low-pressure chamber 75 along the path.

  With respect to the oil flow caused by the forward movement of the upper piston 34, the opening area A2 of the second orifice 76 is smaller than the opening area A1 of the first orifice 74. Therefore, the resistance of the second orifice 76 having a small opening area is used. The hydraulic pressure in the piston chamber 30 increases and a reaction force is generated in the piston 34. By rotating the right rotor 22 connecting the axle shaft of the right rear wheel against the reaction force applied to the piston 34, a torque proportional to the square of the differential rotation is generated.

  On the other hand, in FIG. 5, when both the right coupling 10R and the left coupling 10L are actuated, the piston serving as a discharge step of the pistons 34, 36 by the cam peaks 18, 20 of the right cam 14 and the left cam 16. After the oil discharged from the chamber flows into the communication passage 70 from the second orifice 76 and the third orifice 78 through the discharge check valves 60 and 62, the low pressure chamber 75 passes through the first orifice 74 and from the communication passage 72. Flowing into.

  At this time, since the opening area A1 of the first orifice 74 is smaller than the total opening area (2 × A2) of the second orifice 76 and the third orifice 78, the resistance of the first orifice 74 causes the right coupling 10R and the left coupling. The hydraulic pressure of the piston chambers 30 and 32 at 10 L increases, reaction force is generated in the pistons 34 and 36, and the pistons 34 and 36 are incorporated into the right cam 14 and the left cam 16 fixed to the differential case 12 side. Torque is generated on each axle shaft of the left and right rear wheels connected to the right rotor 22 and left rotor 24 side.

  FIG. 6 shows a torque characteristic 97 during both-side operation and a torque characteristic 98 during one-side operation in the hydraulic power transmission device of the present invention. First, the torque characteristic 97 during both-side operation is based on the opening area A1 of the first orifice 74, and the torque T proportional to the square of the flow rate Q passing through the first orifice 74, that is, the torque T proportional to the square of the differential rotation ΔN. This is the same as the torque characteristic 146 when the two-side operation is performed in the conventional apparatus of FIG.

  On the other hand, in the hydraulic power transmission device of the present invention, torque characteristics 98 at the time of one-side operation in which either one of the right coupling 10R or the left coupling 10L is operated are provided corresponding to each. It is determined depending on the flow rate Q of the opening area A2 of the second orifice 76 or the third orifice 78, and the fixed relationship of 8 to 1 when only the opening area A1 of the first orifice 74 is used can be eliminated.

Therefore, the torque characteristic 98 at the time of one-side operation is different from the torque characteristic 98 at the time of one-side operation, which is determined by the opening area A2 of the second orifice 76 and the third orifice 78, which is determined by the opening area A1 of the first orifice 74.
A2 <A1 <(2 × A2)
It is possible to design freely as long as the relationship is maintained.

  In the above-described embodiment, the second orifice 76 and the third orifice 78 are provided on the valve plates 64 and 66 located on both sides of the block member 68, but not the valve plates 64 and 66 but the block member 68. You may provide in the communicating path 70. FIG. That is, the second orifice 76 and the third orifice 78 may be provided at appropriate positions as long as they are in the middle of the flow path to the discharge ports 56 and 58 of the right rotor 22 and the left rotor 24 on the upstream side of the first orifice 74. it can.

  In the above embodiment, the switching structure in which the intake check valve is provided in the piston through hole provided in the left and right couplings and the discharge check valve is provided on the discharge side of the piston chamber is taken as an example. However, it is a matter of course that a structure in which a valve plate is disposed between the left rotor 24 and the right rotor 22 to switch between the suction and discharge flow paths without depending on such a one-way check valve.

In the above-described embodiment, the case where the hydraulic power transmission device of the present invention is provided on the rear wheel side for an FF type four-wheel drive vehicle is taken as an example. By applying this hydraulic power transmission device, it can be applied in exactly the same manner.

Sectional drawing which showed one Embodiment of this invention Explanatory drawing of the cam used in FIG. Left and right end views of the left valve plate in FIG. Sectional drawing of the block member of FIG. Explanatory drawing when only the left coupling is activated per hydraulic circuit of the embodiment of FIG. The graph which showed the torque characteristic with respect to the differential rotation by this invention Illustration of a four-wheel drive vehicle equipped with a twin coupling type hydraulic power transmission device Explanatory drawing when coupling on both sides is activated per hydraulic circuit diagram of conventional twin coupling type hydraulic power transmission Explanatory drawing of road surface condition that causes both-side operation and one-side operation Graph showing torque characteristics for differential rotation with conventional devices

Explanation of symbols

10: Hydraulic power transmission device 10R: Right coupling 10L: Left coupling 12: Differential case (housing)
14: right cam 16: left cam 18, 20: cam surface 22: right rotor 24: left rotor 25: thrust bearing 26, 28: connecting shaft hole 29: through hole 30, 32: piston chamber 34, 36: piston 38, 40: ball 41, 42: return spring 44, 46: suction groove 48, 50: suction port 52, 54: suction check valve 56, 58: discharge port 60, 62: discharge check valve 64, 66: valve plate 68: block Members 70, 72: Discharge communication passage 74: First orifice 75: Low pressure chamber 76: Second orifice 78: Third orifice 80: Fitting groove 82: Fitting protrusion 84: Communication grooves 86a to 86c, 88a to 88d: Sliding Contact surface 87: Accumulator chamber 90, 91: Pin hole 92: Crimp surface 94: Accumulator piston 96: Return spring

Claims (2)

A housing that is provided between three shafts that can rotate relative to each other, is connected to the first shaft, forms a pair of cam surfaces having two or more peaks on both inner side surfaces, and has a low pressure chamber inside ;
Is coupled to the second shaft and third shaft is rotatably and oppositely accommodated in said housing, a pair of rotors formed axially against a plurality of piston chambers to said cam surface,
Each of the plurality of piston chambers is housed so as to be able to reciprocate under the pressure of a return spring and is driven by the cam surface during relative rotation between the first and second or first and third shafts. A plurality of pistons;
Provided through the piston from the low pressure chamber of the piston chamber external to the suction port communicating with the piston chamber, and a plurality of inlet check valve to suck the oil opens only during retraction of the pistons,
A plurality of discharge check valves provided in a discharge port that penetrates the piston chamber and communicates with the outside of the piston chamber from the piston chamber, and opens only when each piston moves forward to discharge oil;
Comprising a discharge communication passage for communicating the discharge port of the plurality of discharge check valve to said low pressure chamber, which is fixed in placed in said housing between said pair of rotors in which the first orifice is disposed in the discharge communication passage block Members,
In the hydraulic power transmission device that transmits torque according to the rotational speed difference between the first shaft, the second shaft, and the third shaft,
In each of the communication paths from the discharge ports of the pair of rotors on the upstream side of the first orifice provided in the discharge communication path of the block member, a second orifice and a third orifice having a smaller opening area than the first orifice are provided. A hydraulic power transmission device provided.
  2. The hydraulic power transmission device according to claim 1, wherein when the second orifice and the third orifice have the same opening area, the opening area of the first orifice is set to the opening of each of the second and third orifices. A hydraulic power transmission device having a larger area than the total opening area of the second and third orifices.

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