JPS63101568A - Speed difference responsive type coupling - Google Patents

Abstract

PURPOSE:To substantially extend a fatigue failure life of roll running surfaces, by allowing working liquid to escape from an accumulator chamber toward the inside of a housing when the accumulator chamber generates a pressure exceeding a preset value. CONSTITUTION:A return feed oil path 100 is constituted of a valve hole 101, drilled penetrating to an accumulator chamber 90, and a clearance path 102, formed in a combined surface between a drive housing 30 and a rotor 40, in the center shaft part of the rotor 40. And a one-way valve 103 of ball valve construction is provided in the valve hole 101. In this way, when the accumulator chamber 90 generates a pressure exceeding a preset value, working fluid can be allowed to escape from the accumulator chamber 90 through the return feed oil path 100 into the housing 30, accordingly an increase of Hertz stress, generated in a contact surface between a cam surface and a piston type cam body 50 due to an abnormal rise of internal pressure in a side of the rotor 40, is eliminated, and a fatigue failure life of roll running surfaces can be substantially extended.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotation difference sensitive joint used as a driving force distribution device, a differential limiting device between left and right wheels, etc. of a four-wheel drive vehicle, etc.

(Prior Art) As an example of a prior rotation difference sensitive type joint, there is a joint as described in the specification and drawings of Japanese Patent Application No. 129424/1987, which was previously proposed by the present applicant.

This advanced joint uses a piston-type cam body having a seal ring, and the seal ring is designed to achieve the high sealing performance required to exhibit the desired transmission torque characteristics.

(Problem to be Solved by the Invention) However, in this type of previous joint, the sealing performance between the cylinder chamber and the piston type cam body was very high, so it was difficult to carry out long-term durable operation. Then, the hydraulic oil in the housing gradually enters the accumulator chamber.
Eventually, the pressure becomes abnormally high, causing an increase in Hertzian stress on the contact surface between the cam surface and the piston-type cam body, which hastens the fatigue failure of the raceway surface.

Describing the mechanism by which hydraulic oil infiltrates into the accumulator chamber, first, during the process in which the piston-type cam body is pushed into the cylinder chamber under pressure, the seal ring fits perfectly against the cylinder wall due to the cylinder internal pressure. The oil film left on the cylinder wall after the seal ring has passed is extremely thin. However, when the piston-type cam body is extending outward, the pressure inside the cylinder chamber is low, so the pressure of the seal ring against the cylinder wall is weak and the oil supplied from inside the housing to the cylinder wall is pushed to the surface. The oil film left on the cylinder wall after the seal ring passes through is thicker than during the pushing process. Therefore, the amount of oil in the cylinder chamber side increases, exceeding the absorption limit of the accumulator chamber that absorbs oil amount fluctuations.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems, and in order to achieve this purpose, in the present invention, provided between relatively rotatable input and output shafts, A rotation difference sensitive joint comprising a flow rate generation means for causing an amount of fluid to flow according to a rotational speed difference between the two shafts, and in which the transmission torque between the input and output shafts is controlled by the flow resistance of the fluid. The means includes a housing formed integrally with one of the input/output shafts and having a cam surface on an inner circumference, a rotor formed integrally with the other input/output shaft and inserted into the cam surface, and a rotor that is integrally formed with the other input/output shaft and inserted into the cam surface. a piston-type cam body having a seal ring that is supported and in circumferential contact with the cam surface and reciprocates in the radial direction when the housing and rotor rotate relative to each other; and a plurality of cylinder chambers whose volume changes as the cam body reciprocates. , a fluid path formed in the rotor that connects each cylinder chamber through an orifice, an accumulator chamber formed at the end of the fluid path, and when the pressure in the accumulator chamber exceeds a set pressure, The means is characterized in that it includes a return oil passage that releases hydraulic oil toward the inside of the housing.

(Function) Therefore, in the rotation difference sensitive joint of the present invention, since the above-mentioned means are used, when relative rotation occurs between the housing and the rotor, the cam body in circumferential contact with the cam surface will move against the cam surface. In the fluid chamber, which reciprocates in the radial direction depending on the shape and whose volume changes as the cam body reciprocates, fluid pressure is generated due to flow resistance due to the orifice, and due to the difference in relative rotational speed between the rotating members of the housing and rotor. A corresponding torque is transmitted from one shaft to the other.

Furthermore, when the accumulator chamber exceeds the set pressure, the hydraulic oil is released from the 7 accumulator chamber toward the housing by the return oil passage, so the increase in internal pressure on the rotor side, including the accumulator chamber, is suppressed.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In describing this embodiment, a rotation difference sensitive joint provided in the engine drive power transmission system of a four-wheel drive vehicle will be taken as an example.

First, the configuration of the embodiment will be explained based on the drawings shown in FIGS. 1 to 5.

As shown in FIG. 5, the rotation difference sensitive joint A of the embodiment has the following characteristics:
It is installed in the middle of the rear wheel drive system of a four-wheel drive vehicle based on front wheel drive as a joint that serves as both a center differential and a drive power distribution control device to the rear wheels.

The drive system of a four-wheel drive vehicle to which the embodiment coupling A is applied includes an engine l and a transmission (including a clutch) as a front wheel drive system. , front differential 3, front drive shaft 4.5. It is equipped with a front drive shaft joint 6..., front wheels 7, 8, and the rear wheel drive system includes a transfer gear train 9, a front propeller shaft 10, a center propeller shaft (input shaft) 111, and a rotation difference sensitive joint ( Flow rate generating means) A, rear propeller shaft (output shaft) 12, propeller shaft joint 13..., center bearing 14, rear differential 15, rear drive shaft 16.1
7. Rear drive shaft joint 18..., rear wheel 19.20.

The front differential 3 is a differential device for the front wheels 7 and 8 that is interposed between the final gear 21 of the transmission 2 and the front drive shaft 4.5.

The transfer gear train 9 is a driving force splitting device that extracts engine driving force from the differential case 22 of the front differential 3 to the rear wheels 19, 20 side, and is housed in a transaxle case 23 together with the transfer gear train 9 and the front differential 3. It is being

The rear differential 15 is a differential device for the rear wheels 19.20 that is interposed between the rear propeller shaft 12 and the rear drive shaft 16.17.

The configuration of the rotation difference sensitive joint A of the embodiment will be explained.

As shown in FIGS. 1 to 4, the embodiment joint A includes a drive housing (housing) 30, a rotor 40, a driving piston (piston type cam body) 50, a cylinder chamber 60, an orifice oil passage 70, and a regulator oil passage. 8
0, an accumulator chamber 90, and a return oil passage 100 are the main components.

The drive housing 30 is a member that is integrally provided with the center propeller shaft 11, which is an input shaft, by bolting or the like, and has a substantially onigiri-shaped cam surface 31 formed on its inner circumference.

The rotor 40 is inserted into the cam surface 31 of the drive housing 30, and the rear propeller shaft 12, which is an output shaft, is integrally provided with bolts or the like, and a shaft fixed to the drive housing 30 is attached to the rotor 40. ) It is provided in a fixed state in the axial direction while allowing relative rotation by the y-pub plate 41.

The rotor 40 has twelve cylinder holes 42 formed at equal intervals in the radial direction at positions facing the cam surface 31.

The driving piston 50 is connected to the cylinder hole 4
2, the piston-type cam body is provided in an oil-tight state by a seal ring 51, and is composed of a driving pawl 50a circumferentially surrounding the cam surface 31, and a piston 50b facing the cylinder chamber 60, and is connected to the drive housing 30. It reciprocates as it rotates relative to the rotor 40.

The cylinder chamber 60 is a chamber formed between the cylinder hole 42 and the driving piston 50, and changes in volume as the driving piston 50 reciprocates.

The orifice oil passage 70 is a radial oil passage formed in the rotor 40 and has one end opened to the cylinder chamber 60 and the other end opened to the 7-cumulator chamber 90. is provided with an orifice 71.

The regulator oil passage 80 is the orifice oil passage 70.
This is a radial oil passage formed in the rotor 40 in the same manner as shown in FIG. A one-way valve 81 having a pole valve structure is provided to allow flow only from the cylinder chamber 60 to the cylinder chamber 60.

The orifice oil passage 70 and the regulator oil passage 80 are connected in the middle to form a Y-shaped oil passage.

The accumulator chamber 90 is a chamber formed at the central axis of the rotor 40, and absorbs an increase or decrease in the amount of oil by temporarily storing and releasing hydraulic oil, and is provided in an oil-tight manner so as to be able to reciprocate on the rotor 40. It includes an accumulator piston 91, a retainer 93 fixed by a stopper ring 92, and a disc spring 94 interposed between the piston 91 and the retainer 93.

The return oil passage 100 is an oil passage that releases hydraulic oil from the accumulator chamber 90 into the drive housing 30 when the pressure in the accumulator chamber 90 exceeds the set pressure.
A gap path 1 is formed between a valve hole lO1 that is drilled through the central axis of the drive housing 30 and the rotor 40, and a gap path 1 that is formed between the combined coupling surface of the drive housing 30 and the rotor 40.
02, and a one-way valve 103 having a Pall valve structure is provided in the valve hole 101.

Note that the one-way valve 103 is connected to the check pole 1.
03a, a check spring 103b, and a retainer pole 103c.

Next, the operation of the embodiment will be explained.

(B) When no rotational speed difference ΔN occurs When driving in a straight line at low to medium speeds on a dry asphalt road, etc., when no rotational speed difference ΔN occurs between the front and rear wheels,
Since there is no relative rotation between the drive housing 30 and the rotor 40 and the driving piston 50 does not reciprocate in the radial direction, there is no generation of torque ΔT transmitted to the rear wheels 19 and 20 by the rotation difference sensitive joint A, and the engine is driven. Power is from front wheel 7
, 8 becomes the front wheel drive state.

However, even when there is no rotation speed difference ΔN between the front and rear wheels, when driving straight on a highway at high speed, the rotor 4 rotates at high speed as the rear wheels 19.20 rotate.
Centrifugal force Fc acts on the driving piston 50 provided at 0, and the driving piston 50 is pressed against the cam surface 31 by this centrifugal force Fc, as shown in FIG. , transmission torque ΔTco will be generated. The centrifugal force Fc is: m'v2 Fc = - m: Mass (driving piston) r - Distance from the rotation center axis to the mass center of gravity V: Rotor rotation speed, which is the square of the rotation speed V, that is, the vehicle speed V. occurs proportionately.

Therefore, when driving straight at high speed on a highway, etc., the rear wheel 19
．． The transmission torque ΔTco to the 20 side is generated, resulting in a four-wheel drive state, and high-speed straight running stability can be improved.

(b) When a rotational speed difference ΔN occurs When starting or accelerating by pressing the accelerator pedal suddenly, or when driving on both roads, snowy roads, muddy roads, etc., the front wheels, which are the driving wheels. 8 slips and there is a rotational speed difference Δ between the front and rear wheels.
When N occurs, relative rotation occurs between the drive housing 30 and the rotor 40, and due to this relative rotation, the driving piston 50 in circumferential contact with the cam surface 31 reciprocates in the radial direction. When trying to reduce the volume of the cylinder chamber 60 by moving toward the center,
The pressure inside the cylinder chamber 60 increases due to the flow resistance caused by the orifice 71, and the hydraulic pressure obtained by multiplying this generated hydraulic pressure and the pressure-receiving area of the piston 50 becomes a force that presses the driving piston 50 against the cam surface 31, and this pressing is caused by a force. Accordingly, a transmission torque ΔT to the rear wheel 19.20 side is generated.

The torque ΔT transmitted to the rear wheels 19 and 20 is expressed as a quadratic function, as shown by the solid line in FIG. The curve shows the transmission torque characteristics,
The higher the vehicle speed V is, the more transmission torque ΔTc due to centrifugal force is added.

Therefore, if the front wheels 7.8 slip.

According to the degree of slip of the front wheels, the drive power distribution is automatically controlled from front-wheel drive to four-wheel drive, improving starting performance and acceleration, and improving performance on both roads and on snowy roads. It is possible to improve the running performance and the ability to escape from muddy ground.

Also, even when making a small turn at low speed, a slight difference in rotational speed ΔN between the front and rear wheels occurs due to the difference in the turning trajectory between the front and rear wheels.
At this time, the transmission torque ΔT to the rear wheel 19.20 side is small, so the rotational speed difference ΔN between the front and rear wheels is absorbed by the rotational difference sensitive joint A (center differential function).
, the occurrence of tight corner braking phenomenon is prevented.

In addition, when turning at high speed, a large rotational speed difference ΔN occurs between the front and rear wheels, resulting in a four-wheel drive state where the torque ΔT transmitted to the rear wheels is high, so there is a limit due to the relationship between driving force and cornering force. Turning performance (limit speed during cornering) increases.

To describe the movement of hydraulic oil when the rotational speed difference ΔN as described above occurs, first, during the process in which the driving piston 50 is pushed into the cylinder chamber 60 while receiving pressure, due to the cylinder internal pressure. The seal ring 51 moves while being tightly pressed against the inner wall of the cylinder hole 42, and the oil film left on the inner wall of the cylinder hole 42 after the seal ring 51 has passed becomes extremely thin.

On the other hand, when the driving piston 50 is in the outward extension process, the internal pressure of the cylinder chamber 60 is low;
The hydraulic oil passes through the one-way valve 81 and enters the cylinder chamber 6.
However, the pressure of the seal ring 51 against the inner wall of the cylinder hole 42 is weak and the drive housing 3
Move the seal link 51 with the oil inside 0 on the surface.
The oil film left on the inner wall of the cylinder hole 42 after passing through is thicker than during the pushing process.

Therefore, the hydraulic oil in the drive housing 30 gradually enters the rotor 40 side.

On the other hand, the accumulator chamber 90 is preloaded higher than atmospheric pressure by an accumulator piston 91 and a disc spring 94 in order to absorb the thermal expansion of the hydraulic oil and the volume change of each cylinder chamber 60. 3
As the hydraulic oil in the rotor 40 gradually enters the rotor 40, the pressure will eventually exceed the desired set pressure.

However, when the accumulator chamber 90 exceeds the set pressure, the one-way valve 103 opens and the hydraulic oil in the accumulator chamber 90 is returned to the drive housing 30 through the gap path 102, so the internal pressure of the accumulator chamber 90 is set to the set pressure. It can be kept below the pressure.

As explained above, the rotation difference sensitive joint A of the embodiment
In this case, the following effects can be obtained.

■ Since the dry pink histone 50 is arranged to contact the cam surface 31 from the inside in the radial direction, the centrifugal force Fc that acts on the driving piston 50 when the rotor 40 rotates at high speed creates a difference in rotational speed between the front and rear wheels. Even when ΔN does not occur, a predetermined transmission torque ΔTco is generated at high vehicle speeds, improving high-speed running stability, and when a rotational speed difference ΔN occurs, the torque transmission characteristic is such that the transmission torque ΔTc is added, that is, the rotational speed difference ΔN It is possible to obtain torque transmission characteristics (FIG. 6) corresponding to the vehicle speed V and the vehicle speed V.

■ Since the rotor 40, which is located inside of the rotor 40 that rotates relatively, has an oil chamber 60 and an oil passage 61, when the rotor 40 rotates at high speed, the oil flows through the oil passages 70, 80 and the accumulator chamber 90. Almost no centrifugal force is exerted on the hydraulic oil, stable torque transmission characteristics are obtained, and there is no cause of whirling. be done.

■ The structure is a shock absorber type, and the cylinder chamber 60 has a high sealing performance that prevents oil leaks with just the seal ring 51, so torque is transmitted according to the torque transmission characteristics even in the region of low rotational speed difference ΔN. Torque ΔT can be generated.

■ Since the cam surface 31 is formed on the inner periphery of the drive housing 30, the overall diameter of the cam surface 31 can be made large, which allows the cam surface 31 to be machined with high precision and to reduce the unevenness of the cam surface 31. Since the rotation speed becomes smooth, it is possible to prevent collision noise between the cam surface 31 and the driving piston 50 even if the rotational speed difference ΔN is large.

■ The end of each oil passage 70.80 is connected to the accumulator chamber 10.
Since it is guided to 0, it not only absorbs fluctuations in the oil amount, but also acts as a damper for the impactful torque generated in the torque transmission system, and also acts as a means of compensating for wear due to durability of the sliding parts of the driving piston 50 and other parts. .

■ Since the one-way valve 81 is arranged in the radial direction, the valve pole will not come off the valve seat due to the influence of centrifugal force on the valve pole, unlike when it is arranged in the axial direction (the valve spring is relatively small). When the internal pressure of the accumulator chamber 90 is high (the spring force is weak), generation of transmission torque that is not caused by the rotation difference is prevented.

■ Return oil passage 10 that returns hydraulic oil to the drive housing 30 side when the internal pressure of the accumulator chamber 90 exceeds the set pressure
0, the Hertzian stress on the contact surface between the cam surface 31 and the driving piston 50 increases due to an abnormal increase in the internal pressure on the rotor 40 side.

The fatigue failure life of the raceway can be greatly extended without accelerating the fatigue failure of the raceway.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, the rotation difference sensitive joint of the present invention is not limited to the application examples shown in the embodiments, but can also be installed in the middle of the front propeller shaft of a rear-wheel drive based four-wheel drive vehicle, or can be installed between the left and right wheels. It can also be applied as an operation restriction means.

In addition, this embodiment shows an example of a combination of a driving pole and a piston as an example of a piston type cam body, but
It may also be an integral driving piston as described in Japanese Patent Application No. 129424/1988, which was previously proposed by the present applicant.

(Effects of the Invention) As explained above, in the differential rotation sensitive joint of the present invention, when the accumulator chamber formed at the end of the fluid path exceeds the set pressure, the accumulator chamber is moved into the housing. Since the method is equipped with a return oil passage that releases hydraulic oil toward The effect is that the fatigue fracture life can be significantly extended.

[Brief explanation of the drawing]

1 is a longitudinal sectional side view showing a rotational difference sensitive joint according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line I-I in FIG. 1, and FIG. FIG. 4 is an enlarged view of the main parts of the embodiment joint, FIG. 5 is a schematic diagram showing an engine drive system to which the embodiment joint is applied, and FIG. 6 is a torque transmission characteristic diagram of the embodiment joint. A... Rotation difference sensitive joint (flow rate generation means) 11... Center propeller shaft (input shaft) 12... Rear propeller shaft (output shaft) 30... Drive housing (housing) 40... Rotor 50... Driving piston (piston type cam body) 60... Cylinder chamber 70... Orifice oil path 71... Orifice 80... Regulator oil path 90... Accumulator chamber 100... Return oil road

Claims (1)

[Scope of Claims] 1) A flow rate generating means is provided between relatively rotatable input and output shafts and causes a flow of fluid in an amount corresponding to the rotational speed difference between the two shafts, and the flow resistance of the fluid causes the flow resistance of the fluid to flow. In a rotation difference-sensitive joint in which transmission torque between output shafts is controlled, the flow rate generating means includes a housing that is integrally formed with one of the input and output shafts and has a cam surface on the inner circumference, and a housing that is integrally formed with one of the input and output shafts and has a cam surface on the inner circumference, and a piston-type cam having a rotor formed integrally with the rotor and inserted into the cam surface, and a seal ring supported by the rotor and in circumferential contact with the cam surface and reciprocating in the radial direction when the housing and rotor rotate relative to each other. a plurality of cylinder chambers whose volume changes as the cam body reciprocates, a fluid path formed in the rotor and connecting each cylinder chamber via an orifice, and a fluid path formed at an end of the fluid path. A rotation differential sensitive joint characterized in that it is provided with an accumulator chamber and a return oil passage that releases hydraulic oil from the accumulator chamber into the housing when the pressure in the accumulator chamber exceeds a set pressure.