JPH03213729A - Hydraulic power transmission coupling - Google Patents

Abstract

PURPOSE:To suppress the temperature rise of a coupling within the allowable limit by prohibiting the movement of an accumulator piston at the time of the coupling temperature rising to the specified value, and generating frictional torque between an input and an output shafts by the pressure of sealed oil through braking mechanism. CONSTITUTION:When a coupling is moved by the expansion/contraction of oil sealed therein and the temperature of the coupling rises, an accumulator piston 24 for absorbing the expansion of oil moves to the left, and upon reaching the set temperature, a push rod 45 is brought into contact with clutch plates 47, 48. When the temperature further rises, pressure in a hydraulic chamber 41 rises, so that the clutch plate 47 is pressed to the clutch plate 48 through a clutch facing 48A, and braking force acts between an input and an output shafts, that is, between a cam housing 3 and a rotor 4. In this case, the braking force is intensified proportionally to the rise of temperature. Accordingly, when the temperature of the coupling reaches the specified value because of bad road running or the like, the differential rotation of the coupling is lowered to suppress exothermicity in the coupling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic power transmission joint used for distributing driving force in a vehicle.

[Prior Art] In Utility Application No. 63-125959, the present applicant discloses a spool that is housed so as to continuously change the opening area of a discharge passage, a piston that moves due to the expansion of oil due to a rise in temperature,
a pull rod that is fixed to the piston, passes through the spool, and has an engaging portion at an end capable of suppressing the spool;
We are proposing a hydraulic power transmission joint equipped with

In addition, in Japanese Patent Application No. 63-311531, the present applicant has proposed an orifice in the main passage that communicates the fluid discharge passage and suction passage, and when the discharge passage side reaches a predetermined discharge pressure, it resists a spring. We have proposed a hydraulic power transmission joint equipped with an orifice valve that moves when the orifice valve moves, and a needle valve that closes the orifice when the orifice valve moves.

Next, FIG. 7 shows the torque characteristics of these conventional examples.

In Fig. 7, A is the lock setting torque at which the joint locks, B is the generated torque when entering a tight corner with the lock in place, and C is the differential rotation speed that occurs when entering a tight corner without a locking mechanism. , D indicates the torque at which the temperature rise reaches the permissible limit during continuous operation, and E indicates the torque when driving on rough roads.

[Problems to be Solved by the Invention] However, in the former case, with such conventional hydraulic power transmission joints, it takes time for the temperature of the joint to drop, so the joint may become damaged due to driving on rough roads, etc. Once locked, it was difficult to release the lock, and driving on paved roads in such conditions would result in tight corner braking, and excessive torque would be generated in the drive system, causing damage to the drive system.

As a countermeasure to this problem, there was also the problem that increasing the design strength of the drive system would increase costs.

In addition, in the latter case, if the lock setting torque is set low, the locking differential rotation speed will also be low (this will not only cause the joint to lock when turning a tight corner at high speed, but also cause tight corner braking. There was a risk that the vehicle would become unstable, and like the former, there was a risk of damage to the drive system.

If the lock setting torque is set high in order to avoid such problems, there is a problem that the joint may not lock even when desired depending on the road surface conditions, and the temperature of the joint may rise abnormally.

The present invention has been made in view of these conventional problems, and is capable of improving running performance on rough roads, reliably preventing a rise in temperature of the joint, and preventing tight corner play kinks on paved roads. The purpose of this invention is to provide a hydraulic power transmission joint that can suppress the phenomenon to a non-problematic level and reduce the design strength of the drive system to reduce costs.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a pump that is provided between relatively rotatable input and output shafts and is driven by a difference in rotational speed between the two shafts, and a pump that is driven by a rotational speed difference between the two shafts. In a power transmission joint that is equipped with means for generating flow resistance in the discharge passage, and in which the transmission torque between the input and output shafts is controlled by the flow resistance, the temperature of the joint is maintained at a predetermined level by movement due to expansion and contraction of oil sealed in the joint. The system is equipped with an accumulator piston that becomes unable to move when it reaches a value of , and a brake mechanism that generates friction torque between the input and output shafts using the pressure of the sealed oil.

[Function] In the present invention, friction is created between the input and output shafts due to the pressure of the sealed oil and the accumulator piston, which moves due to the expansion and contraction of the oil sealed in the joint and becomes unable to move when the temperature of the joint rises to a predetermined value. Since it is equipped with a brake mechanism that generates torque, when the temperature of the joint rises to a predetermined value, the accumulator piston, which absorbs the oil expansion, stops working, and when the temperature rises further, the pressure inside the joint rapidly increases. start.

This pressure increases as the temperature of the joint increases.

By operating the brake mechanism using this pressure, a braking force acts between the input and output shafts, and the higher the temperature, the stronger the braking force becomes.

Therefore, when the temperature of the joint reaches a predetermined value due to driving on a rough road, etc., the differential rotation of the joint decreases due to the braking action.
Heat generation inside the joint also decreases.

Therefore, the temperature of the joint does not significantly exceed a predetermined value, and the braking force acting on the joint does not exceed the torque required to maintain the joint in a locked state when driving on rough roads.

On the other hand, the torque required to maintain the joint in the locked state when driving on rough roads is sufficiently smaller than the torque that acts on the joint when entering the paved road in the locked state and tight corner braking occurs, and is approximately It is 1/4.

This can also be explained from the coefficient of friction between the tires and the road surface. That is, the coefficient of friction is about 0.8 on paved roads, and about 0.2 on sandy roads.

From the above, even if you enter a paved road with the brakes applied due to driving on a rough road, the degree of tight corner braking phenomenon will be 1 compared to when you enter with the brakes locked.
/4.

Although this value is larger than the normal state in which the brake does not act, this situation does not occur frequently and poses no practical problem.

Additionally, the design strength of the drive system can also be lowered accordingly, leading to cost reductions.

[Example] Embodiments of the present invention will be described below based on the drawings.

1 to 6 are diagrams showing one embodiment of the present invention.

First, to explain the configuration, in Figures 1 to 3, 1
1 is a cam with a cam surface 2 formed on its inner surface, and the cam 1 is connected to an output shaft or an input shaft, and rotates integrally with the output shaft or input shaft. Further, the cam 1 is fixed to a cam housing 3, and the cam nozzle 3 rotates integrally with the cam 1.

A rotor 4 is rotatably housed in the cam housing 3. The rotor 4 is connected to the input shaft or the output shaft, and rotates together with the input shaft or the output shaft.

A plurality of plunger chambers 5 are formed in the rotor 4 in the axial direction, and a plurality of plungers 6 are formed in the plunger chamber 5.
is slidably housed via a return spring 7.

31 is a rotary valve provided on the outer periphery of the rotor 4, and the rotary valve 31 has a positioning protrusion 33 that engages with a notch 32 formed in the cam housing 3; It has a suction port 35 that functions as a suction valve depending on its positional relationship with the hole 34. Further, a discharge passage 36 communicating with the plunger chamber 5 is formed in the rotor 4, and a discharge valve 37 is interposed in the discharge passage 36 by a spring 38.

A high pressure chamber 16 communicates with the discharge passage 36 via a discharge valve 37, and an orifice valve 19 forming an orifice 18 is housed in the high pressure chamber 16 so as to be movable by a spring 17. When the discharge pressure reaches a predetermined value, the orifice valve 19 moves to the right and closes the orifice 18. A low pressure chamber 20 is formed in the rotor 4 on the right side of the orifice valve 19 in the figure, and the low pressure chamber 20 is connected to a passage 29,
It communicates with the plunger chamber 5 through an oil groove 21 formed on the outer diameter of the rotor, a suction port 35 of the rotary valve 31, and a suction hole 34 of the rotor 4.

In addition, there is a blank plug 39 at the bottom of the plunger chamber 5.
is provided.

The oil that has passed through the orifice 18 flows through the oil groove 21 and the suction port 35 of the rotary valve 31, as shown by arrow A.
, is sucked into the plunger chamber 5 through the suction hole 34. The friction torque between the rotor 4 and the rotary valve 31 is set to be larger than the friction torque between the cam nozzle 3 and the rotary valve 31,
When the direction of differential rotation changes, the rotary valve 31 rotates together with the rotor 4 until the protrusion 33 hits the notch 32, and then rotates integrally with the cam housing 3.

22 is a thrust block that rotates integrally with the cam housing 3; 24 is an accumulator piston that rotates integrally with the cam housing 3 and is movable in the axial direction; a hydraulic chamber 41 is provided between the thrust block 22 and the accumulator piston 24; is formed, and the hydraulic chamber 41 communicates with the inside of the joint via a passage 42 formed in the thrust block 22.

A spring 44 is interposed between the retainer 43 fixed to the cam housing 3 and the accumulator piston 24, and a bushing rod 45 is inserted through the retainer 43.
is fixed to the accumulator piston 24. Clutch plates 47, 48 are spline-coupled to the cam housing 3 and the flange portion 46 of the rotor 4, and the clutch plates 47, 48 are pressed by the bushing rod 45 to generate braking force. The differential rotation speed between the cam housing 3 and the rotor 4 is reduced by the action of the braking force. Clutch plate 47.
There is a gap 49 between the bushing rod 48 and the bushing rod 45, but when the temperature exceeds a set value, the bushing rod 45 hits the clutch plates 47, 48, and the sealed oil has nowhere to escape, so the oil pressure in the hydraulic chamber 41 increases.

Note that 26, 27, and 50 are stop rings, 25 is an oil seal, and 28 is a mounting hole for the input/output shaft.

Next, the effect will be explained.

When there is no difference in rotation between the cam 1 and the rotor 4, the plunger 6 does not operate and no torque is transmitted. Note that at this time, the plunger 6 is pressed against the cam surface 2 by the return spring 7.

Next, when a rotation difference occurs between the cam 1 and the rotor 4, the plunger 6, which is in the discharge stroke, is pushed in the axial direction by the cam surface 2 of the cam 1.

Therefore, the plunger 6 pushes out the oil in the plunger chamber 5 from the discharge passage 36 through the discharge valve 37 to the high pressure chamber 16, and the suction port 34 is connected to the rotary valve 31.
(See Figure 4).

The oil pushed out into the high pressure chamber 16 is supplied to the low pressure chamber 20 through an orifice 18 formed by an orifice valve 19 . At this time, the oil pressure in the high pressure chamber 16 and the plunger chamber 5 increases due to the resistance of the orifice 18, and a reaction force is generated in the plunger 6. Torque is generated by rotating the cam l against this plunger reaction force, and the torque is transmitted between the cam 1 and the rotor 4.

Furthermore, when the cam 1 rotates, the plunger 6 enters the suction stroke, and the oil in the low pressure chamber 20 flows through the passage 29 and the oil groove 21.
, is sucked into the plunger chamber 5 from the suction port 35 of the rotary valve 31 through the suction hole 34, and returns along the cam surface 2 of the cam 1.

In this way, the suction port 34 is forcibly opened by the rotary valve 31 (see FIG. 4).

Here, as shown in FIG. 5(A), if the temperature is below the set value, the clutch plate 47. There is a gap 49 between the bushing rod 48 and the bushing rod 45, and the accumulator piston 24 can move freely by absorbing changes in the volume of oil sealed inside the joint, and is pressed by the spring 44 to create a slight preload inside the joint. Adding.

In this state, the brake mechanism does not operate, so the transmitted torque characteristic becomes the characteristic shown in F in FIG. 6.

When the temperature rises, the accumulator piston 24 moves to the left in the figure, and when the set temperature is reached, the bushing rod 4
5 is a clutch play) 47.48. The state is shown in FIG. 5(B).

As the temperature rises further, the oil pressure inside the joint rapidly increases because there is no place for the sealed oil to escape.

This oil pressure acts on the accumulator piston 24 and moves the bushing rod through 45 to the clutch plate 47.4.
8, a brake torque proportional to the oil pressure is generated between the input and output shafts.

Note that this oil pressure increases as the temperature increases, so the brake torque also increases as the temperature increases.

The transmission torque characteristic when this temperature exceeds the set value is the 6th
This is shown by G in the diagram, and H is the torque generated when turning a tight corner in this state. As described above, when the temperature of the joint rises above the set value, the differential rotation of the joint decreases due to the braking force, and the heat generated inside the joint also decreases.

Therefore, the temperature of the joint does not significantly exceed the set value, and the braking force acting on the joint does not exceed the torque required to maintain the joint in a locked state when driving on rough roads.

On the other hand, the torque required to maintain the joint in the locked state when driving on rough roads is sufficiently smaller than the torque B that acts on the joint when the joint enters the paved road in the locked state and a tight corner braking phenomenon occurs. It is about 1/4.

Therefore, even if the vehicle enters a paved road with the brakes applied due to driving on a rough road, the degree of tight corner braking will be reduced to about 1/4 compared to when the vehicle enters in a locked state.

Although this value is larger than the normal state in which the brake does not act, this situation does not occur frequently and poses no practical problem.

Additionally, the design strength of the drive system can also be lowered accordingly, leading to cost reductions.

In addition, in the present invention, the clutch plate 47.48
Although the case has been described in which the accumulator piston 24 is provided in the vicinity of the clutch plate 47, 48, the present invention is not limited to this. It's okay.

[Effects of the Invention] As explained above, according to the present invention, the accumulator piston moves due to the expansion and contraction of the oil sealed in the joint and becomes unable to move when the temperature of the joint rises to a predetermined value, and the sealed oil A brake mechanism is installed that generates friction torque between the input and output shafts using the pressure of By applying the minimum necessary brake torque between the input and output shafts of the joint, the temperature rise of the joint can be suppressed to within the permissible limit.

What's more, even if the driver enters a paved road with the brakes applied due to driving on rough roads, it is possible to suppress the tight corner braking phenomenon to a level that does not pose a practical problem, and it also reduces cost by lowering the design strength of the drive system. can be achieved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a sectional view thereof, Fig. 3 is an explanatory diagram of the main part thereof, Fig. 4 is a diagram showing the opening/closing timing of the suction valve and the discharge valve, and Fig. 5 Figures (A) and (B) are diagrams illustrating the operation of the accumulator piston, Figure 6 is a diagram showing the torque characteristics of the present invention, and Figure 7 is a diagram showing the torque characteristics of the conventional example. In the figure, 1... cam, 2... cam surface, 3... cam housing, 4... rotor, 5... plunger chamber, 6... plunger 7... return spring, 16... High pressure chamber, 17... Spring, 18... Orifice, 19... Orifice valve, 20... Low pressure chamber, 21... Oil groove, 22... Thrust block, 24...・Accumulator piston 25...Oil seal, 26.27...Stop ring, 28...Mounting hole, 29...Passage, 31...Rotary valve, 32...Notch, 33. ...Protrusion, 34...Suction hole, N, 35...Suction boat, 36...Discharge path, 37...Discharge valve, 38...Spring, 39...Mekura plug, 41... Hydraulic chamber, 42... Passage, 43... Retainer, 44... Spring, 45... Bush rod, 46... Flange portion, 47.48... Clutch plate, 48A... Facing, 49 ...Gap, 50...Stop ring.

Claims (1)

[Scope of Claims] A pump provided between relatively rotatable input and output shafts and driven by a difference in rotational speed between the two shafts, and means for generating flow resistance in a discharge path of the pump, the flow resistance being controlled by the flow resistance. In the power transmission joint in which the transmission torque between the input and output shafts is controlled by A hydraulic power transmission joint characterized by being provided with a brake mechanism that generates friction torque between the input and output shafts using pressure.