JPS61108014A - Driving coupling device for 4 wheel drive - Google Patents

Abstract

PURPOSE:To prevent the occurrence of brake phenomenon through relief of working oil when the oil temperature of a differential pump is decreased to a given temperature, by a relief valve for low temperature compensation which discharges working oil from the discharge side of a suction delivery outlet. CONSTITUTION:A coupling device body 13 for 4 wheel drive is formed with a vane pump VP, serving as a hydraulic pump, and a hydraulic circuit 21. A rotor 19 is coupled to a second rotary shaft 14 which transmits a driving force to rear wheels, and a cam ring 20a and a flange 20c are coupled to a first rotary shaft 11 which transfers a driving force to front wheels. Low temperature compensating mechanisms M, having a temperature sensor S and relief valve V, are located on a communicating passage 39, through which a check valve 28 and a second oil passage OL2 are intercommunicated, and a communicating passage 40 through which a check valve 29 and a first oil passage OL are intercommunicated. This causes a part of a discharge pressure to be relieved when working oil is at a low temperature, resulting in prevention of the occurrence of braking phenomenon of low temperature oil.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive coupling device for driving front wheels and rear wheels with the same engine, and more specifically to a low oil temperature compensated drive coupling device.

[Conventional technology]

Four-wheel drive (4-wheel drive) in which the front and rear wheels are driven by the same engine.
In 4WD) 41, there is a slight difference in the effective radius of the front and rear tires, and the difference in the rolling path of the wheels during cornering causes the tires to slip, causing unreasonable force to act on the drive system. It is necessary to provide means to prevent this.

For this reason, conventional full-time four-wheel drive vehicles drive even if there is a difference in rotational speed between the #&1 rotating shaft that transmits driving force to the front wheels and the second rotating wheel that transmits driving force to the rear wheels. A differential device called a center differential is used to transmit power, and it is disadvantageous compared to part-time 4-wheel drive vehicles in terms of weight, size, and cost, and because differential rotation is possible. There are cases where four-wheel drive cannot be achieved when wheel drive is required, and the device becomes even more complex, such as requiring a deblocking mechanism.

On the other hand, many part-time four-wheel drive vehicles do not have a center differential, and if there are problems with four-wheel drive, such as tight corner braking caused by cornering, the driver can switch to two-wheel drive. This has the disadvantage that driving operations are complicated.

Therefore, a four-wheel drive drive coupling device may be considered that includes a hydraulic coupling mechanism that can mutually transmit driving force between the first rotation shaft and the second rotation shaft.

[Problem that the invention seeks to solve]

However, such a hydraulic connection? When a vane pump is used as a fihlF differential pump, when there is a difference in rotation between the front and rear wheels, hydraulic pressure is generated in the vane pump, this hydraulic pressure is converted into torque, and the torque is transmitted from the slower rotating side to the farthest rotating side. Ru.

As shown in Figure 5, the torque characteristics of a differential pump change as the viscosity of the hydraulic oil changes due to changes in oil temperature, and at low oil temperatures, the torque characteristics shown by the broken line in the figure are obtained. At normal oil temperature (80 to 150°C), something as shown by the solid line in the figure is obtained.

As described above, immediately after the Ennon is started, the oil temperature is low and the viscosity of the hydraulic oil is high, so the rise of the pump generated torque T with respect to the pump rotational speed difference ΔN is very rapid.

For this reason, the pump generated torque due to the difference ΔN in rotational speed of the front and rear wheels during cornering is larger when the oil temperature is low than when the oil temperature is high, and acts in the direction of suppressing the difference ΔN in rotational speed between the front and rear wheels. Braking torque increases when the vehicle is hot, causing excessive torsional torque in the powertrain system such as the propeller shaft, uneven tire wear, and poor driving feeling.

The present invention aims to solve these problems by relieving the discharge pressure when the temperature of the hydraulic oil in the follower pump falls below a predetermined value, thereby preventing braking at low oil temperatures. It is an object of the present invention to provide a drive coupling device for four-wheel drive that can prevent this phenomenon.

[Means for solving problems]

Therefore, the four-wheel drive drive coupling device of the present invention includes a first rotating shaft that transmits driving force to the front wheels of a vehicle, a second rotating shaft that transmits driving force to the rear wheels, and the first rotating shaft that transmits driving force to the rear wheels of the vehicle. A hydraulic coupling mechanism is provided between the rotating shaft and the second rotating shaft and capable of mutually transmitting driving force, and the hydraulic coupling is configured as a differential pump type coupling mechanism. , a hydraulic circuit for receiving hydraulic oil from the suction and discharge port of the connected 1fi groove, and a temperature sensor for detecting the temperature of this hydraulic oil are installed in the connected sleeping structure. A low-temperature compensating relief valve is installed which discharges the hydraulic oil from the discharge side of the suction/discharge port to the oil tank when the temperature of the hydraulic oil falls below a predetermined temperature in response to a detection signal. There is.

[For production]

In the above-described four-wheel drive drive coupling device of the present invention, when the temperature of the hydraulic oil detected by the temperature sensor falls below a predetermined temperature, the low temperature compensation relief valve is opened and the discharge 1 of the differential pump is (The hydraulic oil discharged from the q@containing discharge port is discharged to the oil tank, thereby reducing the pressure of the discharge side hydraulic oil and reducing the high pump generated torque at low oil temperature.

〔Example〕

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
tjSl~7 shows a four-wheel drive drive coupling device as a first embodiment of the present invention, FIG. 1 is a schematic diagram showing its cross section, and FIG. 2 shows its low temperature compensation relief valve. 3 is a schematic configuration diagram showing a drive system of an IJL image equipped with this device, FIG. 4 is a vertical sectional view of this device, FIG. 5 is a graph for explaining its operation, and FIG. The figure is a schematic diagram showing a partial modification of the hydraulic circuit, FIG. 7 is a sectional view showing a modification of the low temperature compensation relief valve and temperature sensor, and FIGS. FIG. 9 shows a four-wheel drive drive coupling device as an embodiment, and FIG. 58 is a schematic diagram showing the main parts of the hydraulic circuit, and FIG. 9 is a sectional view showing the temperature compensation relief valve and temperature sensor.

As shown in Fig. 3, the gearbox 2 is connected to the ennon 1 equipped with an I device, and the driving force is taken out from the drive gear (or 4-speed counter gear) 4 attached to the output shaft 3, and the vane pump type The signal is transmitted to the gear cam ring 20e of the four-wheel drive coupling device main body 13 as a coupling mechanism.

The gear cam ring 20e rotates the hashing 20 and connects the housing 20 to the first rotating shaft (
Outside? The driving force is transmitted from the gear 7 to the differential device 10 for the front wheels 9 via the gear 111111, and the front wheels 9 are driven.

That is, the driving force transmitted to the four-wheel drive coupling device main body 13 is directly transferred to the first rotating shaft 11 from the gear cam ring 2.
0e, and furthermore, gear 7, differential i!
10 to the front wheel 9! ! be done.

The driving force passing through this four-wheel drive coupling device main body 13 is
A second rotating shaft (
A bevel gear mechanism 15 that changes the direction of rotation, and a propeller pongee 12. A differential 17 for the rear wheel 16 via a bevel gear mechanism 15'
The driving force is transmitted to drive the rear wheels 16.

As shown in Fig. 1.2.4, this four-wheel drive coupling device main body 13 is composed of a vane pump ■P serving as a hydraulic pump (hydraulic coupling mechanism) and a hydraulic circuit 21 attached thereto. , the rotor 19 of the vane pump VP is connected to the rear wheel 1
A cam ring portion 20a that is connected to the second rotating shaft 14 that transmits driving force to the housing 20 and that constitutes the housing 20.
and a 7-run wheel 20c are connected to a first rotating shaft 11 that transmits driving force to the front wheels 9.

In the vane pump VP as a hydraulic pump, a large number (10 holes in this case) of holes 19b are formed at equal intervals in the circumferential direction on the outer circumferential surface 19a of the rotor 19. Each of the cam rings 1i20
A vane 18 that can be slidably contacted with the inner circumferential portion 20d of a is fitted.

Further, each part is formed so that the axial clearance between the cover 20b of the housing 20 and the vanes 18 and rotor 19 is below a predetermined value, so that the oil film does not break, and the pressure retainer of the housing 20 20f
Similarly, each part is formed so that the axial clearance between the vane 18 and the rotor 19 is equal to or less than a predetermined value.

The sum of these gaps is set to be less than or equal to a predetermined value.

In addition, the vane pump vP discharges an amount of oil proportional to the number of times the vane pump vP is used. Rotor 19 and cam ring part 2
0a, i.e., the rotation axis 11 of i@1.
When relative rotation occurs between the second rotary shaft 14 and the second rotating shaft 14, it functions as a hydraulic pump and generates hydraulic pressure.

Discharge port of vane pump ■P (suction/discharge ports 22 to 27 at the tip of the vane 18 in the relative rotation direction with respect to the housing 20)
411), the rotor 19 and the cam ring portion 20a become like a rigid body and are rotated together by the static pressure through the oil.

For this reason, when opening the cam ring g2oa and the rotor 19, there are three pump chambers 36 to 36 at intervals of 120 degrees from the rotation center line.
38 is formed, and six suction/discharge ports 22 to 27 are formed at approximately 120° intervals, which are suction ports when located on the proximal end side in the rotational direction J direction and serve as discharge ports when located on the distal end side. , the suction/discharge ports 22, 24, 26 and the suction/discharge ports 23, 25, 27, which are spaced at 120° intervals and have the same function, are provided with a mechanism that allows oil to flow to the stationary side even when the cam ring portion 20a is rotating. The first oil passage OL and the second oil passage OL communicate with each other.

Further, an oil reservoir (oil tank) 30 at the bottom of the transmission case 44 is communicated with each of the first oil passage OL and the second oil passage OL via check valves 28 and 29, respectively. Oil path OL1. Only flow to OL2 is allowed, and tJSl oil path OL, and!
Two discharge pressure control relief valves 33 and 34 are provided between #2 oil passage OL and #2 oil passage OL, which allow both oil passages OL and OL2 to communicate with each other when the discharge pressure exceeds a predetermined pressure.

These reliefs 033 and 34 are urged in the closing direction by springs 33a and 34a, respectively.

A communication passage 39 for relieving the discharge pressure to the oil ff30 is connected to the oil passage OL of f52, which is open between the check valve 28 and the suction and discharge ports 23, 25, and 27. A relief device 6ffM for low temperature compensation is inserted.

Furthermore, a communication passage 40 for relieving discharge pressure to the oil [30] is connected to the oil passage OL of ff1l between the check valve 29 and the suction and discharge ports 22, 24°26, and this communication passage A 171)-7 mechanism M for low temperature compensation is inserted in 40. - A temperature sensor (oil temperature sensor) S and a relief valve (2) are provided in the leaf structures M, M for use with these low temperature compensation levers.

The snap-type bimetal 72 as the temperature sensor S has
Heat-sensitive oil such as suction oil is circulated through the oil passage 65, and a heat-resistant rubber 73 that constitutes the valve body of the relief valve (2) is attached to the side surface of the bimetal 72.

The rubber 73 is configured to be able to block communication between the communication passages 39 and 40, and the solid line in FIG. A snap-type bimetal 72 is used as a temperature sensor S.
When low-temperature hydraulic oil is supplied from the communication passage 65 to
The snap-type bimetal 72 is displaced in the direction indicated by the reference numeral in the same figure (corresponding to oil temperature detection No. 46), and the rubber 73 serving as the valve body moves to the valve seat openings 39m and 40 of the communication passage 39.40.
Separate from a, the relief valve (2) is opened, and the communication passages 39 and 40 are communicated.

Furthermore, when hydraulic oil at a temperature higher than a predetermined temperature is supplied to the snap-type bimetal 72 from the communication path 65, the snap-type bimetal 72 is in the state shown by the two-dot chain line in FIG. Displaced in the direction indicated by the symbol H in the figure, the rubber 73 serving as the valve body moves into the communication path 39.
The relief valve V is closed by covering the valve seat openings 39a and 40a of 40, and the communication passages 39 and 40 are cut off.

With such a hydraulic circuit 21, the discharge pressure always acts on the valve element of the relief valve 33 or the relief valve 34, regardless of the relative rotation direction between the rotor 19 and the cam ring part 2011, and the oil reservoir 30 It will communicate with the mouth.

In addition, the cover 20b and the 17th run no. 20c that constitute the 1st rung 20 of the vane pump ■P are connected to the transmission case 44 via bearings 41 and 42, respectively.
It is pivoted on.

Spline engagement portion 14 on rotor 19 of vane pump VP
The second rotating shaft 14 connected via a has bushings (bearings) 45 on both sides of the spline engagement portion 14a.
．． They are pivotally supported by the cover 20b and the pressure retainer 20'' via 46, respectively.

Then, the bottom part 18b of the vane 18 receives the operating pressure that is reduced through the check valve and the flow path to reduce the discharge pressure from the discharge side suction and discharge port 24, and the tip part 18a of the vane 18 reaches the inner circumferential surface 20d of the haunong 20. energized.

Further, on both end surfaces of the rotor 19, a spring 63 or a ring or the like is attached to the shaft portion 62 as shown by the two-dot chain line in FIG.
5 at a time through the bottom 18b of the vane 18.
You may also press the button.

Further, as shown in FIG. 4, an axial housing #JllS56 where the rotor 19 and the cover 20b are in sliding contact and an axial housing portion 56 where the rotor 19 and the pressure retainer 20' are in sliding contact are provided with an annular hydraulic chamber. 59°59 is formed,
This hydraulic chamber 59.59 communicates with the hole 19b of the rotor 19 and also with the oil passage 39.40.

That is, the hydraulic chambers 59.59 are connected to each suction and discharge port 22.2.
4. Check valve (6th
A check valve (fjS6, reference numeral 31 in the figure) is connected to the second oil passage OL2 connected to each suction/discharge port 23.25°27 and receives high oil pressure via the reference numeral 32f# in the figure).
(see) to receive high oil pressure.

Note that the reference numeral 19c in the figure indicates the inner diameter side fiff of the rotor 19.
5.43 indicates a bearing that supports the first rotating shaft, 47 is a pulsation volume, 48 is an oil guide, 49 is a filter, 50 is a magnet, 51 is a bolt, 54 is an oil path, and 55 is a pulse. Session damper, 68
indicate the lid members, respectively.

Four wheels as the first embodiment of the present invention! Since the g2 effect drive coupling device is constructed as described above, the vane pump ■
The temperature of the hydraulic oil of P is at room temperature (80°C) or above.
80 to 150°C), the snap-type bimetal 72 as the temperature sensor S is in the state shown by the two-dot chain line in FIG.
The low temperature compensation relief valve (2) is maintained in the closed state, and in the state shown below, 1 [both vehicles enter the four-wheel drive state].

In the normal straight-ahead state of the vehicle, the effective radius of the tires of the front wheels 9 and the rear wheels 16 are the same, and the slip rotational speed of the tires is small.
No difference in rotational speed occurs between the first rotating shaft 11 connected to #S2 and the rotating shaft 14 of #S2.

Therefore, vane pump ■P does not generate hydraulic pressure,
Although the driving force is not transmitted to the rear wheels 16 and depends only on the front wheels 9, 1
It will be wheel drive.

However, in a state where the front wheels 9 normally slip within about 1% even without a large slip, such as when the vehicle accelerates straight ahead, this causes a difference in rotation 11i:M degrees between the first rotating shaft 11 and the second rotating shaft 11. If it occurs between the rotating shaft 14 and the vane pump ■P
functions and generates hydraulic pressure according to this rotational speed difference.
(see figure), the rotor 19 and the cam ring portion 20a rotate together, and a driving force corresponding to the oil pressure and the pressure receiving area of the vane is transmitted to the rear wheels 16, resulting in a four-wheel drive state.

In this case, the flow of oil in the vane pump ■P is caused by the relative rotation of the rotor 19 (see symbol B in Figure 1), and the suction and discharge ports 23, 25, and 27 serve as suction ports, and the check valve Oil is sucked in from the oil reservoir 30 via the oil reservoir 30 through the oil reservoir 28, while the suction/discharge port 22°24.26 serves as a discharge port, and at the same time as the check valve 29 is closed, the oil is led to the relief valve 33 for controlling the discharge pressure. , oil is guided to the low temperature compensation relief valve V via the oil passage 40.

In FIG. 1, solid line arrows indicate the flow of discharged oil, and broken line arrows indicate the flow of suction oil.

In this embodiment, the Jl oil passage OL receives a discharge pressure in the relative rotation direction B shown in FIG. The discharge pressures are superimposed and their pulsations are also superimposed, but since the peak phases of the pulsations are different, the variation value of the superimposed pulsations is equal to the variation value of the pulsations for each discharge pressure.

In addition, since the oil passages OL, OL2 and the inner diameter side bottom portion 19c are in communication with each other via the check valve, the vane 18 is always urged toward the inner circumferential surface 20d of the cam ring portion 20a, and when the ennon 1 is started, The driving force transmission characteristics of the vane pump VP are improved.

Further, although the pressure receiving area on the discharge side of each of the suction and discharge ports 22 to 27 is different for each boat, the second rotating shaft 14 is connected to the housing 20 through the bushing (M receiver) 45.46.
Since the rotor 19 is pivotally supported by the rotor 19, it is possible to support the rotor 19 even if an imbalance occurs in the radial force applied to the rotor 19. In this embodiment, the radial load vector on the discharge boat The positions and sizes of the suction and discharge ports 22 to 2, as well as the cam ring portion 20a, are adjusted so that the sum of the sum becomes zero.
The shape of the inner peripheral surface 20d is determined.

Next, if the rotational speed of the i+ii wheels 9 becomes very large compared to the rotational speed of the rear wheels 16, for example, when the front wheels 9 slip on a snowy road, or during sudden acceleration or braking, the rear wheels 16 tend to lock up. If so, the four-wheel drive coupling device main body 13
The rotational speed difference between the first rotating shaft 11 connected to the first rotating shaft 11 and the second rotating shaft 14 becomes very large.

As a result, in the vane pump vP, an oil flow as shown in Fig. 1 occurs and a large hydraulic pressure is generated, but when a predetermined value is exceeded, the relief valve 33 opens against the spring 33a and the discharge pressure becomes almost constant. A four-wheel drive state is established in which a constant driving force corresponding to a constant discharge pressure is transmitted to the rear wheels 16.

Then, as the rotational speed of the front wheel 9 decreases, the rear wheel 1
6's rotational speed increases, reducing the rotational speed difference (
Same as non-slip differential).

In this way, when the front wheels 9 are in a slip state, it is possible to avoid the drive torque to the rear wheels 16 being increased and making it impossible to drive, and when the rear wheels 16 are a little locked, 11τf
The brake torque of the wheels 9 is increased to prevent the rear wheels 16 from locking.

If the rotational speed of the rear wheels 16 becomes extremely large compared to the rotational speed of the front wheels 9, for example, if the front wheels 9 become slightly locked in the brake state, the four-wheel drive coupling device main body 13
The first rotating shaft 11 connected to! l's2 rotation axis 14
A very large rotational speed difference occurs in the opposite direction to that described above.

As a result, in the vane pump VP, an oil flow occurs in the opposite direction to the oil flow shown in the fjS1 diagram, and the suction and discharge ports 221
24 and 26 are suction ports, and oil is sucked in from the oil reservoir 30 via the check valve 29, while the suction and discharge ports 23.
25. 27 becomes the discharge port, and the check valve 28 is closed via the first oil passage OL, and a large hydraulic pressure guided to the relief valve 34 for controlling the discharge pressure acts.
4, a constant driving force is transmitted to the rear wheels 16, resulting in a four-wheel drive state, and furthermore, oil is led to the low temperature compensation relief valve (2) via the oil passage 39.

And after? Increase the brake torque to &16 and
Prevents ring 9 from locking.

Furthermore, during normal cornering, the rotational speed of the front wheels 9 is slightly higher than the rotational speed of the rear wheels 16, resulting in a four-wheel drive state in which brake torque is applied to the front wheels 9 and drive torque is applied to the rear wheels 16. By controlling the discharge pressure in the four-wheel drive coupling device main body 13 so as not to exceed a certain value C7 using the relief valves 33 and 34, as when turning and running, conventional part-time four-wheel drive When a four-wheel drive state is required, the driver's operation is required, but now the switch between four-wheel drive and two-wheel drive is automatically performed, and the rotation of the front wheels 9 and rear wheels 16 is changed. A four-wheel drive state can be obtained with the driving force depending on the speed difference.

Furthermore, in an emergency when the temperature of the hydraulic oil of the vane pump VP falls below a predetermined temperature (e.g. 80°C), such as when starting the Ennon, the snap-type bimetal 7 as the temperature sensor S
2 is in the state shown by the solid line in Figure 2, and the bimetal 72 with heat-resistant rubber 73 moves in the direction shown by the symbol in the figure, and the low temperature compensation relief valve ■ is in the open state. It will become.

As a result, when the hydraulic oil is at a low temperature, the discharge pressure is partially relieved, and even when operating at ground temperature as shown by the broken line in Fig. 5, the characteristics obtained during normal temperature operation as shown by the solid line in Fig. 5 can be obtained. , the torque transmitted to the rear wheel drive system is reduced, resulting in a nearly FF drive state, suppressing the braking phenomenon caused by low oil temperature.

Also, conventional full-time 4-wheel drive! Compared to the center differential that was always installed on l1lJ cars, this device is smaller and more compact, and also reduces weight. As shown in the figure, only one check valve 31, 32 may be provided between the communication passage 39 and the communication passage 40, which face each other and allow only outflow. A relief rock surface M for low temperature compensation may be inserted in the common passage portion of the communication passages 39 and 40.

Further, as the relief Isokare M for low temperature compensation, a temperature sensitive spring 74 made of a shape memory alloy and also serving as a temperature sensor S as shown in FIG. 7 may be used.
In this case, the hydraulic oil on the discharge side is circulated through the hole 75a of the valve body 75 constituting the relief valve (2) for low temperature compensation upstream of the oil passage 65, and the relief valve (2) opens in the communication path 39° as a relief hole at low temperatures. 40 @ in a continuous communication state, and at normal temperature, the communication path 39°40 is in a closed state.

As described above, according to the four-wheel drive coupling device according to this embodiment, the following effects and advantages can be obtained with a simple configuration. (1) The difference in speed between the front wheels and the rear wheels can be reduced. Since this is permissible, it is possible to eliminate problems such as the tight corner braking phenomenon of part-time four-wheel drive vehicles and the complexity of driving operations.

(2) Force is transmitted between the first rotating shaft and the second rotating shaft from the one rotating faster to the one rotating slower, so
One of the front or rear wheels will no longer over-rev.
Wheel spin can be reliably prevented, contributing to vehicle safety.
(3) Compared to the single center differential that was conventionally installed on full-time four-wheel drive vehicles, this system can generate less wind and light air, which can also contribute to lower costs.

(4) The vane 18 is pressed against the inside M[120a of the housing 20, and the gap between the tip j1iff318a of the vane 18 and the inner circumferential portion 20a of the housing 20 is always kept small, so that fluctuations in the discharged hydraulic pressure are small. , rotor 1
(5) In the differential pump type four-wheel drive coupling device, when the relative transmission speed between the front and rear wheels 9 and the housing 20 is constant, the output torque is almost constant.
．． 16, and the front wheel 9 (
Or, since the absolute speed of the rear wheels 16) is proportional to the vehicle speed, the entire range of engine rotation speed (for example, 0 to 5000 rpm)
Good differential torque can be generated over the period.

Further, in the second embodiment of the present invention, the main part A of the hydraulic circuit 21 shown in FIG. 1 is configured as the main part A' in FIG. Passage 3',
40', and a high temperature compensating relief structure M' is inserted in these communication paths 39', 40''.

The low temperature compensation relief mechanism M and the high temperature compensation relief mechanism M' are integrally formed as shown in FIG. 9, and a spring-shaped bimetal 69 is used as the temperature sensor S. This spring-shaped bimetal 69
is fixed at one end to the housing 20 by the support member 70, detects the oil temperature using heat-sensitive oil in the oil passage 65, and when the temperature is high (e.g., 200° C. or higher), the oil is moved in the direction of symbol H in FIG. By extending the hexagonal spring, the spool valve 66 is moved to the state shown by the two-dot chain line in the figure, and the low temperature compensation relief valve V is closed and the high temperature compensation relief valve V' is opened. .

At room temperature (for example, 80 to 150 degrees Celsius), the spool valve 66 is set to the ninth position by setting the diameter of the mainspring within a predetermined range.
The low temperature compensation relief valve (3) and the high temperature compensation relief valve (V') are each closed at the position shown by the line 1 in the figure.

At low temperatures (e.g., below 80°C), by contracting the mainspring in the direction of the symbol in FIG. 9, the return spring 67' moves the entry pool valve 66 to the position shown by the solid line in FIG.
energizes the low temperature compensation relief valve ■ to open state,
The high temperature compensation relief valve v' is closed.

In this way, since the bimetal 69 is formed into a spiral shape, its displacement can be increased.

The structure of the pond is almost the same as that of the first embodiment, and in FIG. 8.9, the same reference numerals as in FIGS. 1 to 7 indicate almost the same parts.

In this embodiment as well, the same effects as in the tjS1 large example can be obtained in the oil temperature range from low temperature to normal temperature, and the following effects can be obtained in the oil temperature range from normal temperature to high temperature. can.

In an emergency when the temperature of the hydraulic oil of the vane pump VP exceeds a predetermined temperature (200°C) due to a long period of time in which the rotational speed difference ΔN between the front and rear wheels is large, the bimetal 69 operates as the mainspring as the temperature sensor S. As a result, the spool valve 66 moves in the direction indicated by the symbol H in the figure, and the high temperature compensation relief valve V' becomes open. If the vehicle is in a no-7 state, the four-wheel drive state is not achieved, and the torque transmitted to the rear wheel drive system is reduced, resulting in an FF drive state, which suppresses the rise in oil temperature.

That is, in the case of a differential pump such as such a vane pump, a relief valve for controlling the discharge pressure (reference numeral 33.3 in Fig. 1) is used.
(Refer to 4) Before opening, the discharged oil will leak! 'III
Leakage from the clearance, and after the relief valve is opened, the sliding! Everything leaks from the IIIJ section clearance and relief hole. At this time, heat is generated, and the amount of heat generated is proportional to the product of discharge pressure P and discharge IQ.

This product (PXQ) is the pump generated torque T and rotational speed I
If there is a relationship as shown in the fifth column between the pump generated torque T and the circulation speed difference N in proportion to the product with N, the amount of heat generated increases as the rotational speed difference N increases.

Therefore, in this embodiment, when the rotational speed difference N between the front and rear wheels is large continuously, the oil temperature is 200°C or more.
The oil does not rise and the viscosity of the hydraulic oil decreases.
/It is possible to solve the problem that the sliding parts of the pump are seized or the rubber parts such as the sealing material inside the vane pump are deformed and damaged, which impairs the function of the pump.

Further, problems such as a decrease in the torque transmitted to the wheels that change between the driving state and the driven state due to a decrease in the discharge pressure, which may cause the vehicle to lose its function as a four-wheel drive vehicle, can be eliminated.

In this way, in the m2* example, within the predetermined temperature (80 to 15
0°C) or (50 to 200°C), when there is a difference in rotational speed between the front and rear wheels, a four-wheel drive state can be established. Shape memory alloys formed into respective shapes may be used.

In addition, another control mechanism may be separately provided that operates the high temperature compensation relief valve ■' in response to a signal from the temperature sensor S. In this case, in consideration of the ambient temperature of the oil pump VP, The set temperature may be variably controlled to become higher.

Furthermore, it is also possible to apply the present invention to four-wheel drive vehicles other than FF-based vehicles.

〔Effect of the invention〕

As detailed above, according to the four-wheel drive drive coupling device of the present invention, the first rotating shaft transmits driving force to the front wheels of the vehicle, and the ttS2 rotating shaft transmits driving force to the rear wheels. , is provided with a hydraulic coupling mechanism that is interposed between the rotating shaft of the above l)'Sl and the second rotating shaft and can mutually transmit driving force, and the same hydraulic coupling mechanism 8! The mechanism is configured as a differential pump type connecting groove, and the connecting mechanism includes a hydraulic circuit that receives hydraulic oil from the suction and discharge port of the connecting mechanism, and a temperature sensor for detecting the temperature of the hydraulic oil. A low-temperature compensating relief is provided for discharging the hydraulic oil from the discharge side of the suction/discharge port to the oil tank when the temperature of the hydraulic oil falls below a predetermined temperature in response to an oil temperature detection signal from the temperature sensor. The simple structure in which a valve is inserted provides the following effects and advantages.

(1) When the oil temperature of the differential pump falls below a predetermined temperature, the hydraulic oil can be reefed to lower the pump discharge pressure, and braking phenomena at low oil temperatures can be prevented.

(2) Hydraulic oil relief: By adjusting l, the pump torque characteristics (rise characteristics) can be made almost the same as at room temperature.6 (3) By circulating the oil before the heat sensor for oil temperature detection, can be improved.

(4) According to the above item 1, it is possible to prevent the generation of unreasonable torsional torque in the power train system such as the propeller shaft, and also to prevent the occurrence of uneven tire wear and deterioration of the running speed and feeling.

[Brief explanation of the drawing]

Figures Pt51 to 7 show a four-wheel drive drive coupling device as a first embodiment of the present invention. Figure 1 is a schematic cross-sectional view of the device, and Figure 2 is a diagram showing its low temperature compensation relief valve. The sectional view shown, Pt53 is a schematic configuration diagram showing the drive system of a vehicle equipped with this device, FIG. 4 is a longitudinal sectional view of this device, FIG. 5 is a graph for explaining its operation, and FIG. FIG. 7 is a schematic diagram showing a partial modification of the hydraulic circuit, FIG. 7 is a sectional view showing a modification of the high temperature compensation relief valve and temperature sensor, and FIGS. FIG. 8 is a configuration diagram showing the main parts of the hydraulic circuit, and FIG. 9 is a sectional view showing the temperature compensation relief valve and temperature sensor. 1. Horizontal engine, 2. Transmission, 3. Output shaft, 4
・・Drive gear (or 4-unit counter gear), 7...
Gear, 9...Front wheel, 10...Differential device, 11...First rotating shaft (outer shaft), 12...Propeller shaft, 13...4-wheel drive series l1llvc unit as a vane pump type coupling mechanism , 14... Second rotating shaft (inner sleeve), 14a... Spline engagement part, 15° 15'... Bevel tooth J1 mechanism, 16... Rear wheel, 17... Differential gear, 18... vane,
18a...Tip, 18b-Bottom, 19-t7-ta, 19a...Outer circumferential surface, 19b...Hole, 19c...Bottom on inner diameter side, 20...Haunong, 20a...Cam ring part, 20b...・Cover, 20c...7 runno, 20d...
Inner circumferential surface, 20e...Gear cam ring, 20''...Pressure retainer, 21...Hydraulic circuit, 22~27゜Suction/discharge port, 28.29...Check valve, 30...Oil reservoir (oil tank), 31.32...Check valve, 33.
34...Discharge pressure control relief valve, 33a, 3411.
・Spring, 36-38...Pump chamber, 39.39'
, 40.40'...Communication path, 39a, 40a...Valve seat opening, 41-43 knee bearing, 44...T2 Smith, case, 45.46...Bushing (bearing), 47...Pulsation Volume, 48...Oil ID, 49...Filter, 50...Magnet, 5
1...Bolt, 54...Oil passage, 55...Pulsation damper, 56...Axial coexistence part, 59...Capture chamber, 59
a...Inside, 59b...Outside, 62...Shaft, 63...
Spring, 65... Oil path, 67'... Return spring, 68... Lid member, 69φ, spring-shaped bimetal, 70... Support member, 72... Snap-type bimetal, 73... Heat-resistant rubber, 74...・Temperature sensitive spring made of shape memory alloy, 75...valve body, 75a...hole, A,
A'... Main part of the hydraulic circuit, M... Relief mechanism for low temperature compensation, M'... For high temperature compensation +j') -78! Structure, office lady.・・First oil path, OL2・・ptS2 oil path, S・・Temperature sensor (oil temperature sensor), ■・・Relief valve for low temperature compensation,
M'...Relief valve for high temperature compensation, VP/ψ vane valve.

Claims (1)

[Claims] A first rotating shaft that transmits driving force to the front wheels of the vehicle, a second rotating shaft that transmits driving force to the rear wheels, and an interposed device between the first rotating shaft and the second rotating shaft. and a hydraulic coupling mechanism capable of transmitting driving force to each other, the hydraulic coupling mechanism being configured as a differential pump type coupling mechanism, and the coupling mechanism having an operation from the suction and discharge port of the coupling mechanism. A hydraulic circuit for receiving oil and a temperature sensor for detecting the temperature of this hydraulic oil are provided, and when the temperature of the hydraulic oil falls below a predetermined temperature upon receiving an oil temperature detection signal from the temperature sensor, the above-mentioned A drive coupling device for four-wheel drive, characterized in that a low temperature compensation relief valve is installed to discharge hydraulic oil from the discharge side of a suction and discharge port to an oil tank.