JPH0893794A - Fluid pressure control device - Google Patents

Abstract

PURPOSE: To secure a space in an oil pressure supply device by estimating an oil temperature without arranging an oil temperature sensor. CONSTITUTION: When an engine is put in an actuating condition, control signals CS0 and CS1 according to clutch pressure P2 under which the torque allocation ratio of front and rear wheels is set in 50%:50% are outputted to driving circuits 31a and 31b, and count of a count value t1 is started, and the count value t1 is counted until an ON condition detecting signal SA3 is inputted from a hydraulic switch 134 actuated according to clutch pressure Pc. When the ON condition detecting signal SA3 is inputted from the hydraulic switch 134, it is judged that the clutch pressure Pc reaches the clutch pressure P2 , and a working fluid temperature to the actuating time corresponding to the count value t1 is retrieved by referring to a correspondence table to express the correspondence between the actuating time and the working fluid temperature stored in a storage device 7c after being preformed, and the retrieved working fluid temperature is determined as an estimated temperature of working fluid at the present time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer hydraulic control device for a four-wheel drive vehicle which is hydraulically controlled.

[0002]

2. Description of the Related Art Conventionally, for example, in a transfer hydraulic control device for a four-wheel drive vehicle, for example, "service information
No. 629 (R32-2) NISSAN Skyline R32 type 4WD vehicle introduction Nissan Motor Co., Ltd.
As described in "August 1989", after shifting the driving force from the engine to a predetermined driving force by the transmission,
Through a transfer having a wet multi-plate clutch (hereinafter referred to as a clutch), the driving force is distributed according to a predetermined driving force distribution ratio and is transmitted to the output shaft to the front and rear wheels. At this time, the distribution of the driving force in the transfer is controlled by the hydraulic pressure supply device based on the control signal from the control unit to control the clutch pressure, thereby controlling the engagement force of the clutch of the transfer and controlling the distribution of the driving force. Is supposed to do.

[0003]

In the hydraulic pressure supply device for a transfer described in Japanese Patent Application No. 5-348836 previously proposed by the present applicant, the hydraulic pressure supply device for a transfer is directly connected to the output shaft of a transmission and is rotationally driven. A predetermined line pressure P _L is generated by the main pump, and the line pressure P _L is controlled to a predetermined clutch pressure Pc based on a control signal from the control unit. The motor is started when the main pump does not operate sufficiently and the required line pressure P _L cannot be obtained because of insufficient rotational driving force from the transmission, such as during reverse travel. Then, the sub-pump is operated to secure the line pressure P _L required by the hydraulic pressure from the sub-pump and the hydraulic pressure from the main pump.

In the hydraulic pressure supply device, for example, when the vehicle speed is equal to or lower than the preset motor drive vehicle speed NV, the motor is driven, and at this time, operating oil is detected by an oil temperature sensor provided in an oil tank. The motor drive vehicle speed NV is corrected according to the value, the drive control of the motor is performed so as to compensate for the leak amount due to the temperature change of the hydraulic oil, and, for example, the pressure reduced by the line pressure regulator valve, the switching valve The output of the clutch pressure Pc is detected by a hydraulic switch, and abnormality detection or the like is performed based on this detection signal.

However, the transfer hydraulic control device for a four-wheel drive vehicle of the above-mentioned prior application includes both a hydraulic switch and an oil temperature sensor, which reduces the layout space and includes a plurality of sensors. In addition, there is a problem that the number of parts increases and the cost also increases. Therefore, the present invention has been made in view of the above problems, and estimates the oil temperature by using a hydraulic switch, secures a layout space, and enables fluid pressure control capable of reducing cost. The purpose is to provide a device.

[0006]

In order to achieve the above object, a fluid pressure control device according to a first aspect of the present invention, as shown in the basic configuration diagram of FIG. And a fluid pressure control device for outputting a desired control pressure, and a fluid pressure change detection device for detecting a fluid pressure change state at a predetermined location, and a predetermined pressure control by the fluid pressure control device. And a fluid temperature estimation means for estimating the working fluid temperature corresponding to the fluid pressure variation state as the working fluid temperature based on the fluid pressure variation state detected by the fluid pressure variation detection means. It has a feature.

Further, in the fluid pressure control device according to claim 2, the fluid pressure change detecting means according to claim 1 changes the fluid pressure by detecting the operating speed of the valve of the fluid pressure operated valve. It is characterized in that a state is detected, the fluid temperature estimating means calculates and sets a corresponding working fluid temperature from the correlation between the working speed and the working fluid temperature, and estimates this as the working fluid temperature.

Further, in the fluid pressure control device according to a third aspect, the fluid pressure change detecting means according to the first aspect is a fluid pressure detecting means for detecting whether or not the fluid pressure has reached a preset predetermined pressure. Required time to detect the time required to detect that the detection means and the fluid pressure control means have reached a predetermined pressure when the fluid pressure is changed from a preset reference pressure to a predetermined pressure. A detection means, the fluid temperature estimation means, when detecting that the predetermined pressure is reached by the fluid pressure detection means, calculates and sets the corresponding working fluid temperature from the correlation between the required time and the working fluid temperature, It is characterized in that this is estimated as the working fluid temperature.

Further, the fluid pressure control device according to a fourth aspect is characterized in that the fluid pressure detecting means according to the third aspect is a hydraulic switch.

[0010]

In general, the fluid pressure control device according to claim 1 is
Since the viscosity of the working fluid depends on its temperature, and the change amount and rate of change of the fluid pressure also contribute to the viscosity of the working fluid, the fluid pressure control means operates the fluid pressure operated valve to control the fluid pressure. By outputting the desired control pressure, at this time, the fluid temperature estimation means, the working fluid temperature corresponding to the fluid pressure change state of the control pressure detected by the fluid pressure change detection means,
It is estimated as the temperature of the working fluid at the present time.

A fluid pressure control device according to a second aspect of the present invention detects the operating speed of a fluid pressure actuated valve as a fluid pressure change detecting means, and determines the pressure change amount or change rate of the working fluid and the working fluid temperature. From the correlation with, for example, by referring to the correspondence table showing the correspondence between the fluid pressure change state consisting of this operating speed and the working fluid temperature, the working fluid temperature corresponding to the operating speed detected by the fluid pressure change detecting means is searched. , The retrieved working fluid temperature is used as the estimated temperature of the working fluid at the present time.

Further, in the fluid pressure control device according to the third aspect of the present invention, the fluid pressure control means actuates the fluid pressure operation valve to control the fluid pressure to change the fluid pressure from a preset reference pressure to a predetermined pressure. At this time, when the fluid pressure detecting means detects that the fluid pressure has reached a preset predetermined pressure, the fluid temperature estimating means determines whether the pressure change amount or change rate of the working fluid and the working fluid temperature From the correlation, for example, a correspondence table showing the correspondence between the fluid pressure change state consisting of the required time and the working fluid temperature is referred to, the working fluid temperature corresponding to the required time detected by the required time detecting means is searched, and the working fluid temperature is searched. Estimated temperature of.

Further, in the fluid pressure control device according to the fourth aspect, by using the hydraulic switch as the fluid pressure detecting means, in the fluid pressure control device provided with the hydraulic switch, the information of the hydraulic switch already provided is diverted. By doing so, the hydraulic oil temperature can be easily estimated without adding a new sensor or the like.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a part-time four-wheel drive vehicle based on an FR (front engine, rear drive) system, which includes an engine 10 and front left to rear right wheels 12FL.
.About.12RR, a driving force transmission system 14 capable of changing the driving force distribution ratio to the wheels 12FL to 12RR, and a hydraulic pressure as a fluid pressure control device for supplying hydraulic pressure to control the driving force distribution by the driving force transmission system 14. The vehicle is provided with a supply device 16 and a controller 18 as fluid pressure control means for controlling the hydraulic pressure supply device 16.

The driving force transmission system 14 includes a transmission 20 that shifts the driving force from the engine 10 at a selected gear ratio, and the driving force from the transmission 20 to the front wheels 12FL, 12FR and the rear wheels (always driving wheels). ) 12RL, and a transfer 22 divided into 12RR sides. Then, in the driving force transmission system 14, the front wheel driving force divided by the transfer 22 is passed through the front wheel side output shaft 24, the front differential gear 26 and the front wheel side drive shaft 28 to the front wheels 12FL, 1FL.
2FR, while the rear wheel side driving force is transmitted through the propeller shaft (rear wheel side output shaft) 30, the rear differential gear 32 and the drive shaft 34 to the rear wheels 12RL, 1
It is transmitted to 2RR.

FIG. 3 shows the internal structure of the transfer 22. The input shaft 42 and the first shaft 42 are arranged in the transfer casing 40 in a coaxial butted state.
In the output shaft 44, the input shaft 42 is the front casing 40a.
Is rotatably supported by a radial bearing 46 on the first
The output shaft 44 has a radial bearing 48 in the rear casing 40b.
It is rotatably supported via and is arranged so as to be relatively rotatable. Then, the input shaft 42 and the first output shaft 44
Bearings 50 respectively arranged in the front casing 40a and the rear casing 40b in parallel with
The second output shaft 54 is rotatably supported via 52. The input shaft 42 is connected to the output shaft 56 of the transmission 20, the first output shaft 44 is connected to the rear wheel side output shaft 30, and the second shaft
The output shaft 54 is coupled to the front wheel side output shaft 24.

The input shaft 42 and the first output shaft 44 are provided with an auxiliary transmission mechanism 58 and a two-wheel / four-wheel drive switching mechanism 60. The subtransmission mechanism 58 is the planetary gear mechanism 6
2 and a meshing clutch type high / low speed switching mechanism 64 arranged coaxially with the planetary gear mechanism 62. The planetary gear mechanism 62 includes a sun gear 62a formed on the outer circumference of the input shaft 42, an internal gear 62b fixed inside the front casing 40a, a pinion gear 62c meshing with the sun gear 62a and the internal gear 62b, and a pinion gear 62c. And a pinion carrier 62d that rotatably supports the.

The high / low speed switching mechanism 64 includes a plurality of key grooves and inner teeth 64b ₁ provided on the outer periphery of the first output shaft 44.
Is formed at an outer peripheral position of the input shaft 42 that is slidable in the axial direction by spline coupling with the shift sleeve 64b having outer teeth 64b ₂ on the outer periphery and an inner tooth 64b ₁ of the shift sleeve 64b. High speed shift gear 64c and external teeth 64b _{2 of the} shift sleeve 64b
And a low speed shift gear 64d formed on the inner peripheral portion of the pinion carrier 62d that can be meshed with.

When the shift sleeve 64b slides to the high speed shift position indicated by the symbol H, as in the upper side arrangement of the shift sleeve 64b shown by the solid line in FIG. 4, the high speed shift gear 64c and the inner teeth 64b ₁ mesh with each other. It is supposed to do. Further, when the shift sleeve 64b slides to the low speed shift position indicated by the symbol L as in the lower side arrangement of the shift sleeve 64b in FIG. 4, the low speed shift gear 64d and the outer teeth 64b ₂ mesh with each other. . In addition, the shift sleeve 6 shown by the chain double-dashed line
When the shift sleeve 64b moves to the neutral position of the symbol N as in the arrangement on the upper side of 4b, the inner teeth 64b ₁ and the outer teeth 64b ₂ are prevented from meshing with any of the other gears of the high / low speed switching mechanism 64. ing.

Returning to FIG. 3, the two-wheel / four-wheel drive switching mechanism 6
0 is a wet multi-plate friction clutch (hereinafter abbreviated as friction clutch) 66 for changing the driving force distribution ratio for the front and rear wheels.
A first sprocket 68 rotatably arranged on the first output shaft 44, and a second sprocket coaxially connected to the second output shaft 54.
A sprocket 70 and first and second sprockets 68,
It is composed of a chain 72 wound between 70.

The friction clutch 66 includes the first sprocket 6
8, a clutch drum 66a coupled to the clutch drum 66a, a friction plate 66b splined to the clutch drum 66a, a clutch hub 66c splined to the outer circumference of the first input shaft 44, and a clutch hub 66c integrally coupled to the clutch hub 66c. The friction disc 66d disposed between the friction plates 66b and the first output shaft 44
A rotary member 66e disposed on the outer circumference of the clutch member 66e for abutting the friction plate 66b and the friction disk 66d by axial movement toward the clutch drum 66a, and a clutch hub 66c integrally coupled to the clutch hub 66c and the rotary member 66e. The mating pin 66k, the clutch piston 66g mounted on the inner wall of the rear casing 40b and movable in the axial direction, and the clutch piston 6g.
A thrust bearing 66f that transmits the axial movement of 6g to the rotating member 66e, and a cylinder chamber 66h formed between the inner walls of the clutch piston 66g and the rear casing 40b.
And a return spring 66j that applies an urging force to the rotating member 66e toward the clutch piston 66g.

When the clutch pressure Pc is supplied from the hydraulic pressure supply device 16 to the input port 74 formed in the rear casing 40b which communicates with the cylinder chamber 66h, the clutch piston 6 is generated by the pressing force generated in the cylinder chamber 66h.
6g moves to the left in FIG. 3, the movement of the clutch piston 66g is transmitted to the rotating member 66e via the thrust bearing 66f, and the friction plate 66b and the friction disc 66d, which are separated from each other, move the friction disc 66d. And a fastening force corresponding to the clutch pressure Pc due to the frictional force is applied. As a result, the rotational driving force of the first output shaft 44 has a predetermined torque distribution ratio according to the engagement force of the friction clutch 66, and the first sprocket 68, the chain 72, and the second sprocket 70.
Is transmitted to the second output shaft 54 via.

Further, when the supplied clutch pressure Pc decreases and the urging force of the return spring 66j moves the rotating member 66e and the clutch piston 66g to the right in FIG. 3, the friction plate 66b and the friction disc 66d are separated from each other. , The first output shaft 44
Is not transmitted to the second output shaft 54. Also,
The first sprocket 68, the four-wheel drive gear 80 on the outer circumference of the shift sleeve 64b side is provided, when the shift sleeve 64b is moved to the low speed position L in FIG. 4 described above, for external teeth 64b ₂ and the low-speed shift The structure is such that the four-wheel drive gear 80 meshes with the inner teeth 64b ₁ together with the gear 64d. As a result, the shift sleeve 6
The 4b and the four-wheel drive gear 80 form a dog clutch that forcibly connects the first output shaft 44 and the second output shaft 54 at the low speed position L.

The shift sleeve 64b of the high / low speed switching mechanism 64 of the meshing clutch type has a fork (Fig. 4) manually operated by an auxiliary transmission lever (not shown).
The reference numeral 84 indicates a slidable movement to a high speed shift position H, a neutral position N, or a low speed shift position L via the fork tip portion). With the auxiliary transmission lever, 4H range, 4L range, N When the 4H range is selected by the auxiliary transmission lever, the shift sleeve 64b moves to the high speed shift position H, and when the 4L range is selected, the shift sleeve 64b moves at the low speed shift position L. When the N range is selected, the shift sleeve 64b is moved to the neutral position N.

A high speed shift position sensor 86 for detecting that the shift sleeve 64b has slid to the high speed shift position H inside the front casing 40a.
And a low speed shift position sensor 88 for detecting that the shift sleeve 64b has slid to the low speed shift position L.
Is provided. Then, the high speed shift position sensor 86
The detection signal S _H and the detection signal S _L of the low speed shift position sensor 88 are input to the controller 18 described later at any time.

Further, the hydraulic pressure supply device 16 is adapted to supply a predetermined clutch pressure Pc to the input port 74 of the transfer 22 by the circuit configuration shown in FIG.
The hydraulic pressure supply device 16 is a forward / reverse rotation type main pump 100 that is directly connected to an input shaft 42 that is connected to an output side of the transmission 20 and is rotationally driven, and is arranged in parallel with the main pump 100 to drive an electric motor 102. A forward rotation type sub-pump 104 that is rotationally driven is used as a hydraulic power source. The main pump 100 and the sub-pump 104 strain the hydraulic oil in the oil tank 105 into strainers 106a and 108a.
It is inhaled through and is discharged to the discharge side pipes 106b and 108b. An oil element 112 is connected to a converging pipe 110a that converges the pipes 106b and 108b. The oil element 112 is connected to the upstream side (the main pump 100 and the sub-pump 104 side) of the lubricating system 1
The relief path 116 connected to the 14th side is connected.
Further, a line pressure regulating valve 118 is connected to the downstream side (transfer 22 side) of the oil element 112, and pipes 110b, 110c, 110 branched from the converging pipe 110a.
The input sides of the electromagnetic switching valve 120, the clutch pressure adjusting valve 122, and the pressure reducing valve 124 are connected to e, respectively. Further, the output side of the clutch pressure adjusting valve 122 is connected to the input side of a pilot switching valve 126 which is switched to the 4WD mode and supplies the clutch pressure Pc to the transfer 22 when the control pressure is not supplied, and the output of the pressure reducing valve 124. The input side of the duty control solenoid valve 128 is connected to the side.

In the oil tank 105, a hydraulic switch 132 for detecting the pressure reduced by the line pressure regulating valve 118 and a hydraulic switch 134 for detecting the clutch pressure Pc output from the pilot switching valve 126 are provided. The detection signals are output to the controller 18. Here, the clutch pressure control valve 1
22 and the pilot switching valve 126 correspond to the fluid pressure operating valve, and the hydraulic switch 134 corresponds to the fluid pressure change detecting means and the fluid pressure detecting means.

In the actual vehicle, the hydraulic pressure supply device 16 is disposed inside the transfer 22 and sucks the working oil from the oil tank 105.
3, is connected to the first output shaft 44 via the first gear 136a and the second gear 136b, and the sub pump 104 is connected to the electric motor 102 externally attached to the transfer casing 40. .

Next, each component of the hydraulic pressure supply device 16 will be described in detail with reference to FIG. The main pump 100, which is driven in the normal rotation, sucks the working oil from the oil tank 105 through the strainer 106a connected to the end of the suction pipe 106c, and the sub-pump 104 is also a strainer connected to the end of the suction pipe 108c. The hydraulic oil is sucked from the oil tank 105 via 108a. Then, the converging pipe 110
Check valves 106d and 108d are respectively inserted in the discharge pipes 106b and 108b of each pump connected to a, and a bypass passage is provided between the discharge pipe 106b of the main pump 100 and the suction pipe 108c of the sub pump 104. 140 is connected. This bypass 140 is
It is composed of a bypass pipe 140a and three check valves 140b inserted in the bypass pipe 140a. When the discharge pipe 106b is in a negative pressure state, the check valve 140b is in an open state, and the hydraulic oil is It becomes a communication passage that flows in the direction of the dashed arrow.

The relief passage 116 connected to the convergent pipe 110a on the upstream side of the oil element 112 has a relief pipe 116a whose other end is connected to the lubrication system 114 side.
The relief pipe 116a is composed of two check valves 116b with springs. Then, when the filter of the oil element 112 is clogged and the pressure on the upstream side of the oil element 112 becomes equal to or higher than a predetermined pressure, the check valve 116b is opened, and the hydraulic fluid flows in the direction of the dashed arrow. Become.

The line pressure regulating valve 118 is composed of an internal pilot and a pressure reducing valve of the spring type, and has an input port 118 _A connected to the convergent pipe 110a side and a lubricating system 11.
A spool is slidably arranged in a tubular valve housing having internal pilot ports 118 _P1 and 118 _P2 to which primary pressure and secondary pressure are supplied via an output port 118 _B connected to the four side and a fixed throttle. A return spring 118a for urging the spool toward one end is provided. Then, the main pump 100 or the sub pump 1
The supply pressure P _L increased by 04 is the line pressure regulating valve 118.
The pressure is reduced to a predetermined pressure and supplied to the electromagnetic switching valve 120, the clutch pressure adjusting valve 122, and the pressure reducing valve 124. The hydraulic oil flowing out from the output port 118 _B when the pressure reduction is set is returned to the lubricating system 114.

The clutch pressure adjusting valve 122 is composed of an internal, external pilot and spring type pressure adjusting valve, and is connected to the pipe 110c at the input port 1.
22 _A , an output port 122 _B connected to the pilot switching valve 126, an internal pilot port 122 _P1 to which the secondary pressure is supplied as a pilot pressure via a fixed throttle, and an external pilot to which a control pressure is supplied from the duty control solenoid valve 128. A spool is slidably disposed in a tubular valve housing having a port 122 _P2, and a return spring 122a that biases the spool toward one end is disposed. When the pilot control pressure from the duty control solenoid valve 128 is not supplied, the clutch pressure adjusting valve 122 closes the communication passage between the input port 122 _A and the output port 122 _B and does not output the secondary pressure. When the pilot control pressure is supplied from the control solenoid valve 128, the spool is moved and controlled, and the secondary pressure corresponding to the pilot control pressure is output from the output port 122 _B as the clutch pressure Pc.

The pressure reducing valve 124 is composed of an internal pilot and a spring type constant secondary pressure type pressure reducing valve, and has an input port 124 _A connected to the pipe 110 e and an output port 12 connected to the duty control solenoid valve 128.
4 _B, and the internal pilot port 124 _P to the secondary pressure from the output port 124 _B is supplied as a pilot pressure through a fixed throttle, the spool is slidable in a cylindrical valve housing having a drain port 124 _D And a return spring 12 for urging the spool toward one end.
4a is provided. Then, the spool is moved to a predetermined position by the pilot pressure supplied to the internal pilot port 124 _P , so that the input port 12
The primary pressure supplied from 4 _{A is} supplied to the duty control solenoid valve 128 as a control pressure reduced and adjusted to a predetermined pressure.

The duty control solenoid valve 128 has three
An output port configured to be a port 2 position type and connected to an input port 128 _A connected to the pressure reducing valve 124 side, a drain port 128 _D connected to the drain side, and an external pilot port 122 _P2 of the clutch pressure regulating valve 122. 12
8 _B and, and a return spring 128a, normal position 128b spool disposed within the valve causes communication between the output port 128 _B and the drain port 128 _D
If a valve which is controlled to move the operating position 128c which communicates the input port 128 _A and the output port 128 _B.
Then, when the exciting current i ₀ having a required duty ratio is supplied from the controller 18 to the solenoid 128d, the section return spring 1 in which the exciting current i ₀ is in the ON state.
28a against the normal position 128b to the operating position 12
By controlling the movement of the spool to 8c, the pilot control pressure according to the duty ratio is adjusted to the clutch pressure adjusting valve 12
2 is output. Therefore, the clutch pressure adjusting valve 122
When the pilot control pressure is supplied from the duty control solenoid valve 128 to the external pilot port 122 _P2 , the clutch pressure Pc corresponding to the pilot control pressure is output, and the clutch engagement force of the friction clutch 66 is controlled accordingly. Thus, the drive torque is distributed to the front wheels according to the clutch pressure Pc.

Further, the spring offset type solenoid operated directional control valve 120 is constructed in a 3-port two-position type and has an input port 120 _A to which line pressure is supplied and a pilot directional control valve 1.
An output port 120 _B to be connected to the external pilot port 126 _P1 of 26, the drain port 120 and a _D, the drain port 120 a spool disposed within the valve shuts off the input port 120 _A and the output port 120 _B Normal position 120b communicating with _D and input port 120
A valve which is controlled to move the operating position 120c for blocking and drain port 120 _D communicates the _A and the output port 120 _B. When the exciting current i ₁ from the controller 18 is output to the solenoid 120d, the electromagnetic switching valve 120 controls the movement of the spool against the return spring 120a while the exciting current i ₁ continues to be in the ON state. As a result, the operating position 120c is reached, and the pilot control pressure is supplied to the external pilot port 126 _P1 of the pilot switching valve 126. Further, when the exciting current i ₁ from the controller 18 is turned off, the return spring 1
It is returned to the normal position 120b by the pressing force of 20a, and the pilot control pressure supplied to the external pilot port 126 _P1 is extinguished through the drain port 120 _D.

As shown in FIG. 6, the pilot switching valve 126 has an input port 126 _A to which the secondary pressure is supplied from the clutch pressure regulating valve 122 and an output port 126 _B to supply the secondary pressure to the transfer 22. , Electromagnetic switching valve 120
The external pilot port 126 to which the control pressure is supplied when the solenoid 120d is off (off state)
_P1, in a cylindrical valve housing 126i having a drain port 126 _H, spool 126e is disposed slidably, is a valve return spring 126a is disposed for biasing the spool 126e at one end . In addition,
The control pressure from the external pilot port 126 _P1 is supplied in the same direction as the pressing force of the return spring 126a.

Then, the pilot switching valve 126
The pool 126e is the external pilot port 126._P1To
If the pilot control pressure is not supplied, input port 1
26 _AAnd output port 126_BAre cut off, and the output
Heart 126_BIs the drain port 126_D2W communicating with
The movement is controlled to the D mode position 126b.
(The state of the left half cross section of FIG. 6).

Further, the solenoid 12 of the electromagnetic switching valve 120
When 0d is energized (ON state), the electromagnetic switching valve 12
The spool of No. 0 is moved to the operating position 120c, the pilot control pressure is supplied to the external pilot port 126 _P1, and the spool is moved to the 4WD mode position 126c where the input port 126 _A and the output port 126 _B communicate with each other. (Right half cross-sectional state in FIG. 6).

As described above, by driving the pilot switching valve 126 with the pilot control pressure from the electromagnetic switching valve 120, the spool 126e can be driven with a high pilot control pressure, and the sliding passage of the spool 126e is dusted. Even when chips or the like are attached and the sliding resistance of the spool 126e is high, the sliding of the spool 126e can be ensured.

On the other hand, as shown in FIG. 2, the controller 18 is based on the detection signals from the high speed shift position sensor 86, the low speed shift position sensor 88, and the mode selection switch 90, and the exciting current i to the hydraulic pressure supply device 16 is increased. ₀ and i ₁
Is output. The mode selection switch 90 is disposed near the driver's seat and is used for two-wheel drive mode in which the vehicle can be driven by two-wheel drive and the torque distribution ratio of front and rear wheels.
Four-wheel drive lock mode, which allows 0%: 50% to run, and the torque distribution ratio of front and rear wheels according to the running state of the vehicle, rear wheel: front wheel = 100%: 0% to rear wheel: front wheel = 50.
%: It is set to be able to select any one of the three modes of the four-wheel drive auto mode in which the vehicle can continuously change up to 50%. The mode selection switch 90 is capable of mode selection when the 4H range is selected by the auxiliary transmission lever, and when the 4L range is selected, as described above, the first output shaft 44 and the Since the two output shafts 54 are forcibly connected, the mode selection switch 90 cannot select the mode.

The mode selection switch 90 outputs a mode signal D _n = 2 when the two-wheel drive mode is selected, and outputs a mode signal D _n = 4 A when the four-wheel drive auto mode is selected, When the four-wheel drive lock mode is selected, the mode signal D _n = 4L is output. In this embodiment, the same controller 18 also controls the hydraulic pressure supply device 16 so that the hydraulic pressure device 16 can maintain a predetermined hydraulic pressure. Therefore, the hydraulic pressure switches 132 and 134 and the vehicle speed sensor 94 necessary for that purpose are controlled. Prepare,
The control signal S _M to the motor drive circuit 103 is output based on the detection signals from these sensors. In the controller 18, the hydraulic switch 134
The temperature of the hydraulic oil is estimated based on the detection signal from the above, and the exciting currents i ₀ and i ₁ to the hydraulic pressure supply device 16 are corrected based on the oil temperature.

The hydraulic switch 132 turns on the detection signal S _A2 when the hydraulic pressure detection value becomes equal to or lower than the hydraulic pressure set value corresponding to the preset line pressure P _L , and the hydraulic switch 1
34, 50% torque distribution ratio between the front and rear wheels: When 50% next clutch engagement force is equal to or greater than the hydraulic pressure set value corresponding to the maximum and Nariru clutch pressure Pc, and outputs to the controller 18 a detection signal S _A3 as ON .

As shown in FIG. 7, the controller 18 includes a microcomputer 7 for performing a driving force distribution control process and a correction coefficient calculation process for the friction clutch 66, and a driving control for the electric motor 102 to maintain a predetermined hydraulic pressure. A microcomputer 8 for processing, a drive circuit 31a for driving the solenoid 128d by supplying an exciting current i ₀ to the solenoid 128d of the hydraulic pressure supply device 16 in response to a control signal CS ₀ from the microcomputer 7, and the microcomputer The microcomputer 7 includes a drive circuit 31b that supplies an exciting current i ₁ that is turned on / off in response to a control signal CS ₁ from the computer 7 to a solenoid 120d of the electromagnetic switching valve 120 in the hydraulic pressure supply device 16.
And 8 are formed so as to be able to exchange data with each other, and exchange data with each other as necessary.

Then, the microcomputer 7 is
The high speed shift position sensor 86, the low 1 shift position sensor 88, the mode selection switch 90, and the hydraulic switch 134.
To read the detection signal from
An input interface circuit 7a having a D conversion function, an arithmetic processing unit 7b that performs a predetermined arithmetic process for driving force distribution control and a correction coefficient calculation process according to a predetermined program, and a storage unit 7c such as a ROM or a RAM. D / for outputting the control signals CS ₀ and CS ₁ corresponding to the front wheel side torque distribution command value ΔT obtained by the arithmetic processing unit 7b
An output interface circuit 7d having an A conversion function is provided.

The microcomputer 8 reads the detection signals from the hydraulic switches 132 and 134, the mode selection switch 90, and the vehicle speed sensor 94 as respective detection values, and has an input interface circuit 8a having an A / D conversion function. , Arithmetic processing unit 8b, ROM, RA
A storage device 8c such as M and an output interface circuit 8d having a D / A conversion function for outputting the rotation speed command value of the electric motor 102 obtained by the arithmetic processing device 8b as, for example, an analog voltage signal S _M. I have it.

The microcomputer 7 is shown in FIG.
The driving force distribution control process shown in FIG. 1 and the correction coefficient calculation process shown in FIG. 12 are executed at predetermined timings. In the driving force distribution control process, the mode signal D _n from the mode selection switch 90 and the high speed shift position sensor 86 Based on the high speed shift position detection signal S _H , the low speed shift position detection signal S _L from the low speed shift position sensor 88, etc., the front wheel side torque distribution command value ΔT is set, and the set front wheel side torque distribution command value ΔT is set. The duty ratio D for commanding the clutch pressure Pc corresponding to is calculated, and is corrected based on the correction coefficient K _D calculated in the correction coefficient calculation process to set the correction duty ratio D ′. The control signal CS ₀ having the command value corresponding to ′ is output, and the control signal CS ₁ for turning on and off the exciting current is output.

The drive circuit 31a is provided with, for example, a pulse width modulation circuit which outputs an exciting current having a duty ratio according to a command of the control signal CS ₀ which is an analog voltage signal output from the microcomputer 7. ,
The exciting current i ₀ having a duty ratio according to the command of the control signal CS ₀ is supplied to the solenoid 128 of the duty control solenoid valve 128.
output to d.

Further, the drive circuit 31b converts the control signal CS ₁ output from the microcomputer 7 into an exciting current i ₁ having a current value capable of exciting the solenoid 120d of the electromagnetic switching valve 120, and electromagnetically converts this. It outputs to the solenoid 120d of the switching valve 120. Further, the microcomputer 7 executes the correction coefficient calculation process shown in FIG. 12, and when the engine is turned on and when the mode selection switch 90 switches from the two-wheel drive mode to the four-wheel drive lock mode. , The oil temperature of the hydraulic oil is estimated based on the detection signal of the hydraulic switch 134, and the correction coefficient K _D is calculated based on the estimated oil temperature T ₀ .

Further, in the microcomputer 8 of the controller 18 of this embodiment, the hydraulic pressure supply device 16 controls the hydraulic pressure supply device 16 so that it can supply a predetermined hydraulic pressure by an arithmetic processing (not shown) stored in the storage device 8c. For example, when it is detected by the hydraulic switch 132 that the line pressure P _L on the downstream side of the oil element 112 of the converging pipe 110a is lower than a set value, the discharge pressure (oil amount) from the sub pump 104 is controlled. Therefore, a control signal S _M representing a rotation speed command value set according to the estimated oil temperature T ₀ estimated in the correction coefficient calculation process is calculated and supplied to the motor drive circuit 103, whereby the electric motor 10
The rotation speed of 2 is controlled to maintain the line pressure P _L output from the hydraulic pressure supply device 6 at a predetermined pressure.

When the detection signal of the high speed shift position sensor 86 is on and the hydraulic pressure switch 134 detects that the clutch pressure Pc output from the pilot switching valve 126 is zero, the pilot switching valve 126 is abnormal. Judging that there is an alarm. In the motor drive circuit 103, the rotation speed of the electric motor 102 is controlled according to the estimated oil temperature T ₀ by driving the electric motor 102 according to the control signal S _M from the controller 18. There is.

Here, the storage device 7c of the microcomputer 7 stores in advance programs and fixed data necessary for executing the processing of the arithmetic processing device 7b, and
The processing result can be temporarily stored. this house,
The fixed data includes a storage table corresponding to each control characteristic shown in FIGS. 8 to 10. FIG. 8 shows the control characteristics of the front-wheel side transmission torque ΔT with respect to the front-rear wheel rotation speed difference, that is, the front-rear wheel rotation speed difference ΔN. According to this, the distribution of the driving force is increased or decreased according to the value of the rotational speed difference ΔN, and the transmission torque ΔT is increased non-linearly as the rotational speed difference ΔN is increased. Further, FIG. 9 shows the pilot switching valve 126.
It shows the value of the transmission torque ΔT to the front wheels that increases linearly with the increase of the clutch pressure P _C. FIG.
Is the solenoid 128d of the duty control solenoid valve 128
5 shows the value of the clutch pressure P _C of the clutch pressure control valve 122 that increases parabolically in a non-linear manner as the duty ratio D of the exciting current i ₀ increases.

The front and rear wheels of the microcomputer 7
Based on the rotation speed difference ΔN of
When the transmission torque ΔT is determined by reference,
9 and the storage table corresponding to FIG.
The duty that the controller 18 must output
The value of the ratio D can be calculated backward. And the figure
D indicated by 10₁To D₂According to the duty ratio of the range
Clutch pressure P₁To P ₂Is supplied to the friction clutch 66
Then, a predetermined torque corresponding to the engagement force of the friction clutch 66 is obtained.
Distribution ratio: rear wheel: front wheel = 100%: 0% ~ rear wheel: front wheel =
50%: continuously changed up to 50%.

When the duty ratio is D ₁ or less, the clutch pressure Pc is generated and the friction plate 66b and the friction disc 66 of the friction clutch 66 are generated.
It is pressed into contact with d, but the driving force is not transmitted. The driving force distribution control of the friction clutch 66 by the microcomputer 7 of the controller 18 is executed according to the reference calculation process of the driving force distribution control shown in the flowchart of FIG.

The reference calculation process of this driving force distribution control will be briefly described. The calculation process of FIG.
Performed by timer interrupt per T1), first, in step S1, the detection signal S _H and S _L from the high-speed shift position sensor 86 and the low-speed shift position sensor 88, S _H is turned on, S _L is turned off It is determined whether or not the 4H range is selected by the auxiliary transmission lever by determining whether or not.

When the auxiliary transmission lever is not selected in the 4H range, it is determined that the driving force distribution control need not be performed, and the process is terminated and the process returns to the main program. When the 4H range in sub transmission lever is selected, the process proceeds to step S2, the mode signal D _n from the mode selection switch 90 depending on whether a D _n = 2, a two-wheel drive mode Whether or not it is selected is determined. If the two-wheel drive mode is selected, the process proceeds to step S3, and if the two-wheel drive mode is not selected, the process proceeds to step S4.

In this step S3, the electromagnetic switching valve 120
Excitation current i of a current value that does not excite the solenoid 120d of
_The control signal CS ₁ corresponding to ₁ is output to the drive circuit 31b,
Then return to the main program. And step S
4, the mode signal D _n from the mode selection switch 90
It is determined whether the four-wheel drive lock mode is selected based on the above. If the four-wheel drive lock mode is selected, the process proceeds to step S5, and the duty ratio D is set to 50% when the front and rear wheels have a torque ratio of 50%. The duty ratio D2 is set to 50%, and the process proceeds to step S7.

On the other hand, if the four-wheel drive lock mode is not selected in step S4, it is determined that the four-wheel drive auto mode is selected, and the process proceeds to step S6, for example, the first output shaft 44. 8 to 10 based on the rotational speed difference between the front wheel side and the rear wheel side, that is, the rotational speed difference ΔN from the detection values of the rotational speed detection sensor (not shown) disposed on the second output shaft 54. The duty ratio D (D _{1 to} D ₂ ) corresponding to the rotation speed difference ΔN is set by referring to the storage table, and the process proceeds to step S7.

Then, in step S7, the correction coefficient K calculated in the correction coefficient calculation process described later and stored in the storage device 7c.
_D is read, and the correction factor K _D is added to the set duty ratio _D.
The corrected duty ratio D'is calculated by multiplying by, and the control signals CS ₀ and CS ₁ corresponding to the duty ratio D'are output to the drive circuits 31a and 31b in step S8, and the main program is restored.

Next, the processing procedure of the correction coefficient calculation processing in the microcomputer 7 of the controller 18 will be described based on the flowchart shown in FIG. This correction coefficient K
The calculation of _D is executed in a predetermined cycle set in advance, the ignition key switch is turned on and the engine is started, or the mode selection switch 90 is used to switch from the two-wheel drive mode to the four-wheel drive lock mode. Occasionally, the temperature of hydraulic oil is estimated.

In this embodiment, when the ignition key switch is off, the two-wheel drive mode is set regardless of the drive mode selection.
In the controller 18, when the key switch is turned on and the power is turned on, the microcomputer 7 initializes all parameters used in the correction coefficient calculation process to zero.

Then, after these predetermined initial settings, a correction coefficient calculation process is executed, and first, in step S21, it is determined whether or not the flag F1 is F1 = 1. This flag F
1 indicates whether or not the correction coefficient K _D has become K _D = 1. When F1 = 1, it is determined that the correction coefficient K _D = 1 has been established, and thereafter, the correction coefficient K _D It is determined that it is not necessary to perform the calculation process of, and the process is terminated and the process returns to the main program.

If F1 = 1 is not satisfied in step S21, the process proceeds to step S22 and the flag F2 is set to F2.
It is determined whether or not = 1. This flag F2 represents the starting state of the engine. If F2 = 1 is not satisfied, it is determined that the engine is not operating, and the process proceeds to step S23. If F2 = 1, the engine is not activated. It is determined that the operation is in progress, and the process proceeds to step S37.

Then, in step S23, it is determined whether or not the ignition key switch is in the on state and the engine is in the on state. If the ignition key switch is not in the on state, the process is terminated and the main process is terminated. Returning to the program, if the ignition key switch is on, the process proceeds to step S24.

In step S24, the flag F2 is set to F.
2 = 1, and then in step S25, control signals CS ₀ and CS ₁ corresponding to the duty ratio D2 are set to drive circuits 31a and 3 so that the clutch pressure becomes Pc = P _2.
1b, and then, in step S26, the flag F3 is set to F3 = 1 and the flag F4 is set to 0. This flag F3
Indicates whether or not the clutch pressure Pc is being controlled to become P ₂ , and the flag F4 is a process at the time of engine start or at the time of switching from the two-wheel drive mode to the four-wheel drive lock mode. It indicates whether the process is

Then, the process proceeds to step S27, and a predetermined value Δt set in advance is added to the count value t1 to obtain t1 = t.
1 + Δt, and then in step S28, it is determined whether or not the detection signal S _A3 from the hydraulic switch 134 is in the ON state. If the detection signal S _A3 is in the ON state, the clutch engagement force of the friction clutch 66 is determined. It is determined that the clutch pressure Pc has reached the maximum clutch pressure P ₂ and step S
Move to 29. Then, when the detection signal S _A3 is not in the ON state, it is determined that the clutch pressure Pc has not reached the clutch pressure P ₂ yet, and the processing is terminated and the process returns to the main program.

In step S29, the flag F4 is set to F.
It is determined whether or not 4 = 0, and if F4 = 0, it is determined that the processing is at the time of starting the engine, the process proceeds to step S30, and control is performed to enable traveling in the two-wheel drive mode. That is, that is, the control signal CS ₁ that outputs the exciting current i ₁ that does not excite the solenoid 120d is applied to the drive circuit 3
1b to reduce the clutch pressure Pc, and step S3
Move to 1.

On the other hand, the flag F4 is set to F4 in step S29.
If it is not = 0, it is determined that the process is a process at the time of switching from the two-wheel drive mode to the four-wheel drive lock mode, the process directly proceeds to step S31, and is formed in advance and stored in the storage device 7c. The temperature of the hydraulic oil is estimated from the correspondence table shown in FIG.
It is updated and stored in the estimated temperature storage area of c.

Here, the correspondence table of FIG. 13 shows that when the mode selection switch 90 switches from the two-wheel drive mode to the four-wheel drive lock mode, that is, the clutch pressures P ₁ to P which are the output pressures of the pilot switching valve 126. ₂ shows the correspondence between the operating time until the detection signal S _A3 from the hydraulic switch 134 is turned on and the temperature of the hydraulic oil. The rising time of the hydraulic pressure depends on the temperature of the hydraulic oil. When the operating time is 1.5 seconds or more, it is estimated that the oil temperature is -10 degrees or less, and the oil temperature increases as the operating time shortens, When the time is 0.5 seconds or less, it is estimated that the oil temperature is 80 degrees or more.

Also, since the operating time differs depending on the type of hydraulic oil, for example, when applying to a hydraulic pressure supply device using different hydraulic oil, it is necessary to refer to the correspondence table corresponding to that hydraulic oil. There is. Then, step S32
Then, the flag F3 is reset to F3 = 0, and the count values t1 and t2 are reset to zero.

Then, in step S33, the estimated temperature T stored in the storage device 7c is estimated by referring to the characteristic diagram shown in FIG. 14, which is preformed and stored in the storage device 7c. The correction coefficient K _D is set based on the count value t2 and the count value t2. The characteristic diagram of FIG. 14 shows the correspondence between the hydraulic oil temperature T and the elapsed time t from the estimation of the hydraulic oil temperature T. The lower the hydraulic oil temperature T, the more the viscosity of the hydraulic oil becomes. The correction coefficient K _D is set to increase because it increases, and the viscosity of the hydraulic oil decreases as the elapsed time t increases, so the correction coefficient K _D is set to decrease (1 <K _D 1 <K _D 2 <K _D 3).
Then, when the hydraulic oil temperature T and the elapsed time t become equal to or greater than the preset predetermined values Tα and tα, it is assumed that the influence of the change in the viscosity of the hydraulic oil does not occur and the correction coefficient K _D is K.
_The correction coefficient K is set as _D = 1.
_The area where _D = 1 is the normal mode, and the other areas are the correction mode.

[0071] Therefore, in step S33, the hydraulic oil temperature and the estimated temperature, sets the correction coefficient K _D elapsed time as the count value t2, after updating stored correction coefficient K _D in the correction coefficient storage area of the storage device 7c , And proceeds to step S34. In this step S34, a predetermined value Δt set in advance is added to the count value t2 to make t2 = t2 + Δt, and then the process proceeds to step S35. Then, the correction coefficient K _D set in step S35, it is determined whether the K _D = 1, in the case of K _D = 1, the control unit 100 determines that the mode is the normal mode, thereafter, necessary to correct If it is determined that there is no flag, the process proceeds to step S36
After setting = 1, the process returns to the main program, and if K _D = 1 is not set in step S35, the process directly returns to the main program.

Then, in step S22, the flag F2 is set to F.
If 2 = 1, it is determined that the engine is already operating, the process proceeds to step S37, it is determined whether the flag F3 is F3 = 1, and if F3 = 1, , It is determined that the clutch pressure Pc is being controlled, and the process proceeds to step S27. If F3 = 1 is not satisfied, the process proceeds to step S38.

In step S38, the mode signal D _n from the mode selection switch 90 is read, and the two-wheel drive mode is determined based on the mode signal D _n and the mode signal at the time of the previous reading stored in the storage device 7c. It is determined whether or not the four-wheel drive lock mode is switched to the four-wheel drive lock mode. If the two-wheel drive mode is switched to the four-wheel drive lock mode, the process proceeds to step S39 and the flag F3 is set to F.
The flag F is set as the processing at the time of switching from the two-wheel drive mode to the four-wheel drive lock mode by setting 3 = 1.
After setting 4 to F4 = 1, the process proceeds to step S27.
On the other hand, when the two-wheel drive mode is not switched to the four-wheel drive lock mode in step S38, the process directly proceeds to step S33.

Here, step S31 corresponds to the fluid temperature estimating means, and step S27 corresponds to the required time detecting means. Next, the driving force transmission path of the transfer 22 and the running state of the vehicle by selecting the range of the auxiliary transmission lever will be described. First, when the N range is selected, the shift sleeve 64b slides to the neutral position N as shown in the upper side of FIG. In this case, the shift sleeve 6
4b is a high speed shift gear 64c, a low speed shift gear 6
Since neither the 4d gear nor the four-wheel drive gear 80 meshes with each other and the transmission path is not secured, all the wheels are not driven.

When the 4L range is selected, the shift sleeve 64b slides to the low speed position L as shown in the lower side of FIG. 4, and the low speed shift gear 64d and the external teeth 64 are formed.
At the same time as b ₂ meshes, the four-wheel drive gear 80 and the inner teeth 6
4b ₁ meshes. Then, the low speed shift gear 64
Since d is deceleratingly rotated with respect to the input shaft 42 by the planetary gear mechanism 62, the driving force of the input shaft 42 is that of the low speed shift gear 64d, the outer teeth 64b ₂ , the inner teeth 64b ₁ and the first output shaft 44. It is transmitted as deceleration rotation driving force by the transmission path,
At the same time, the low speed rotational driving force of the first output shaft 44 is reduced to the internal teeth 64
b ₁ , four-wheel drive gear 80, first sprocket 68,
Since the deceleration rotation driving force is transmitted through the transmission path of the chain 72, the second sprocket 70, and the second output shaft 54, the vehicle can travel in the low speed four-wheel drive state.

At this time, the driving force of the first output shaft 44 is transmitted to the second output shaft without passing through the friction clutch 66. Therefore, regardless of the mode selection by the mode selection switch 90, the controller 18 causes friction. The driving force distribution control process for the clutch 66 is not executed. Further, when the 4H range is selected, the shift sleeve 64b moves to the high speed shift position H
Since slid up, the detection signal S _H from the high-speed shift position sensor 86 is turned on, thereby, the driving force of the first output shaft 44 is transmitted to the second output shaft via a friction clutch 66 Mode selection switch 9
It is possible to select a mode of 0.

Then, for example, the mode selection switch 90
When the two-wheel drive mode is selected by, the control signal C corresponding to the exciting current i ₁ that does not excite the solenoid 120d
Since S ₁ is output, the solenoid 120d is not excited, so the input port 120 _A of the electromagnetic switching valve 120
The output port 120 _B to the drain port 12
Since the vehicle is in the communication state with 0 _D , the clutch pressure Pc decreases, the clutch engaging force decreases, and the driving force is not transmitted to the rear wheels, so that the vehicle can travel in the two-wheel drive mode.

Further, for example, when the four-wheel drive lock mode is selected by the mode selection switch 90, the duty ratio D is set according to the clutch pressure P _{2 at} which the torque distribution ratio of the front and rear wheels becomes 50%: 50%. duty ratio D ₂ is set for the duty ratio control signal CS ₀ and electromagnetic switching valve 120 to the correction factor K _D for storing D ₂ in the storage device 7c according to the correction duty ratio D 'corrected based on by outputting a control signal CS ₁ for generating an excitation current i ₁ for exciting the solenoid 120d to the drive circuit 31a and 31b, the electromagnetic switching valve 120 spool operating position 120c
And the control pressure is supplied to the pilot port 126 _C of the pilot switching valve 126, whereby the pilot switching valve 126 is controlled to move to the 4WD mode position 126 c, and the drive signal CS ₀ output from the duty control solenoid valve 128 is output. By controlling the clutch pressure adjusting valve 122 with the control pressure according to the above, the secondary pressure from the clutch pressure adjusting valve 122 is output as P ₂ , and the clutch pressure Pc = P _{2 is set} as the clutch pressure Pc = P ₂ via the pilot switching valve 126. 66.

As a result, the driving force of the input shaft 42 is transmitted as a high-speed rotation driving force through the transmission path of the high-speed shift gear 64c, the inner teeth 64b ₁ and the first output shaft 44, and the first output shaft 44 is driven at high speed. The force is transmitted as a high-speed rotational driving force to the transmission path of the friction clutch 66, the first sprocket 68, the chain 72, the second sprocket 70, and the second output shaft 54, which are engaged at a torque distribution ratio of 50%: 50%. Therefore, the vehicle has a front / rear wheel torque distribution ratio of 50%: 5.
It becomes possible to run in the 0% four-wheel drive locked state.

When the four-wheel drive auto mode is selected by the mode selection switch 90, step S in FIG.
In the process of 6, the rotational speed difference between the front wheel and the rear wheel, that is, the rotational speed difference ΔN between the front and rear wheels is calculated from the detection value of the rotational speed detection sensor (not shown), and based on this rotational speed difference ΔN. Storage table Referring to FIGS. 8 to 10, the clutch pressure is P ₁ to
Set the duty ratio D within the range of P ₂ . And
The set duty ratio D is multiplied by the correction coefficient K _D stored in the storage device 7c to obtain the corrected duty ratio D '.
And control signals CS ₀ and CS ₁ corresponding to the corrected duty ratio D ′ are output to the drive circuits 31a and 31b.

Then, the drive circuit 31a causes the control signal CS ₀
The exciting current i ₀ corresponding to the solenoid 128d of the hydraulic pressure supply device 16, the solenoid 12 of the excitation current i ₁ electromagnetic switching valve 120 to the drive circuit 31b corresponds to the control signal CS ₁
By outputting to 0d, the input port 120 _A and the output port 120 _B of the electromagnetic switching valve 120 are brought into communication with each other in the same manner as described above, so that the control pressure is supplied to the pilot port 126 _C of the pilot switching valve 126. As a result, the pilot switching valve 126 is controlled to move to the 4WD mode position 126c, and the duty control solenoid valve 12
The clutch pressure adjusting valve 122 is controlled by the control pressure according to the drive signal CS ₀ output from the control unit 8 so that the clutch pressure adjusting valve 122 outputs the secondary pressure in the range of P ₁ to P ₂ for pilot switching. The clutch pressure P _C is supplied to the input port 74 (friction clutch 66) via the valve 126.

The driving force of the input shaft 42 is transmitted as a high-speed rotational driving force through the transmission path of the high speed shift gear 64c, the internal teeth 64b ₁ and the first output shaft 44, and the first output shaft 4
The high-speed rotation driving force of No. 4 is transmitted through the transmission path of the friction clutch 66, the first sprocket 68, the chain 72, the second sprocket 70, and the second output shaft 54, which are fastened at a predetermined torque distribution ratio, and the vehicle is It becomes possible to run in four-wheel drive auto mode.

Here, the correction coefficient K _D stored in the storage device 7c is set by the correction coefficient calculation process,
When the engine is turned on, the hydraulic pressure temperature is estimated and set on the basis of this estimated temperature, and then corrected and set according to the operating time. When the four-wheel drive lock mode is switched, the hydraulic pressure temperature is estimated again and the correction coefficient K _D is set based on this new estimated temperature.

When the vehicle is in a stopped state and the key switch is turned on from this state, the controller 18 operates and the microcomputer 7 performs a predetermined initial setting, and then, as shown in FIG. The correction coefficient calculation process is executed. At this time, the flags F1 and F2 are initialized to zero, and the engine is in the off state.
Only the processes of steps S21 to S23 of 2 are executed, and the correction coefficient is not calculated.

Then, when the ignition key switch is turned on and the engine is operated from this state, the process proceeds from step S23 to step S24 in FIG. 12, and after setting the flag F2 to F2 = 1, the clutch pressure P
Control signal CS ₀ and solenoid 120d for which c = P ₂
The control signal CS ₁ for commanding an exciting current i ₁ for exciting and output to the drive circuit 31a and 31b, and the flag F3 = 1,
F4 = 0 is set, and counting with the count value t1 is started. As a result, the predetermined exciting currents i ₀ and i ₁ are output from the drive circuits 31a and 31b, so that the input port 120 _A and the output port 120 _{B of} the electromagnetic switching valve 120 are in communication with each other, and the control pressure is piloted. It is supplied to the pilot port 126 _C of the switching valve 126, whereby the pilot switching valve 126 is controlled to move to the 4WD mode position 126 c, and the duty control solenoid valve 12
The clutch pressure adjusting valve 122 is controlled by the pilot control pressure output from the control valve 8, and the secondary pressure is output from the clutch pressure adjusting valve 122.
It is supplied to the input port 74 (friction clutch 66) as the clutch pressure P _C via 26.

At this time, the clutch pressure P _C increases in accordance with the operation of each valve, and when the clutch pressure Pc becomes P ₂ , the hydraulic switch 134 outputs the detection signal S _A3 in the ON state, so that the controller in 18, on the basis of the count value t ₄ at this point, from the correspondence table of FIG. 13, determining an operating oil temperature corresponding to the count value t1. At this time, in the controller 18, until the detection signal S _A3 of the ON state is input from the hydraulic switch 134 in step S28, step S21, step S22, step S3.
The process of 7, step S27, and step S28 is repeated.

When the ON state detection signal S _A3 is input from the hydraulic switch 134 in step S28, the process proceeds to step S29. At this time, the process is when the engine is started and the flag F4 is set to F4 = 0. Therefore, the control signals CS ₀ and CS _{1 for} setting the clutch pressure Pc as the clutch pressure in the two-wheel drive mode are set to the drive circuits 31a and 3a.
1b, whereby each valve operates to reduce the clutch pressure Pc, and the vehicle returns to the runnable state in the two-wheel drive mode.

At this time, for example, when the oil temperature is low,
The operating speed of the valve becomes slow due to the high viscosity of the hydraulic oil, or it takes a long time to change the clutch pressure Pc because the predetermined hydraulic oil amount is not supplied, and the count value t1 becomes 1.5 <t1. In the case such as the case, the oil temperature of the hydraulic oil is estimated to be -10 degrees or less from the correspondence table. On the contrary, when the count value is t1 <0.5, the operating oil temperature is high, and the viscosity of the operating oil is low. Therefore, the operating speed of the valve is high, and the operating oil temperature is 80 degrees or more. presume.

Next, based on the estimated temperature T, the correction coefficient K _D is set from the characteristic diagram of FIG. 14, and at this time, for example, when the estimated temperature T> Tα, at this time, the count value t2 = 0 Therefore, from FIG. 14, the normal mode is entered, and it is not necessary to correct the duty ratio D, and the correction coefficient is set to K _D = 1. Then, for example, when the estimated temperature is T <Tα, the correction coefficient K _D is set to be large because it is necessary to correct the viscosity because the temperature is low and the viscosity of the hydraulic oil is high. Count value t2
Is t2> tα, and when the hydraulic pressure supply device 16 is driven for a predetermined time tα or more, the viscosity of the hydraulic oil becomes low even when the oil temperature is low, and the operation of the valve of the hydraulic pressure supply device 16 or the like is reduced. Assuming that there is no effect, the correction coefficient is set as K _D = 1.

Further, for example, when the estimated temperature is T <Tα and the count value t2 is t2 <tα, the oil temperature is low, the driving time of the hydraulic pressure supply device 16 is short, the viscosity of the hydraulic oil, etc. The correction coefficient K _D is set to be, for example, K _D = K _D 3 because it is greatly affected by. Then, the correction coefficient K _D set based on the estimated temperature T is K _D =
If it is 1, it is determined that it is not necessary to correct the duty ratio D thereafter, and the flag is set to F1 = 1.

If the correction coefficient K _D is not K _D = 1, the controller 18 proceeds to step S until the two-wheel drive mode is switched to the four-wheel drive direct-coupling mode.
Based on the process of 33 and step S34, the correction coefficient K _D is set based on the updated count value t2 and the estimated temperature T, and when the two-wheel drive mode is switched to the four-wheel drive direct connection mode, Steps S39 to S27
And the time until the clutch pressure Pc changes from P ₁ to P ₂ by switching from the two-wheel drive mode to the four-wheel drive direct connection mode, that is, the detection signal S _A3 in the ON state is input from the hydraulic switch 134. Time is counted, the hydraulic pressure temperature T is estimated based on this count value and updated and stored in a predetermined area of the storage device 7c. Thereafter, the correction coefficient K _D is set based on the updated estimated temperature T. .

Therefore, in the driving force distribution control process, the duty set based on FIG. 10 is used based on the correction temperature K _D set according to the estimated temperature T of the hydraulic oil and the driving time of the hydraulic pressure supply device 16. By correcting the ratio D, for example, when the temperature is low, the viscosity of the hydraulic oil increases, so the control signals CS ₀ , CS corresponding to the duty ratio Dm.
_{Even when 1} is output to the drive circuits 31a and 31b, the clutch pressure P _C according to the duty ratio Dm cannot be obtained, but the duty ratio Dm is corrected by the correction coefficient K _D , and the correction duty ratio Dm ′ is used. Control signal C
By outputting S ₀ and CS ₁ , the desired clutch pressure P _C can be reliably obtained even at low temperatures.

Therefore, even if there is no oil temperature sensor,
A correspondence table showing the correspondence between the time required for the clutch pressure P _C to reach a predetermined pressure and the hydraulic oil temperature when the two-wheel drive mode is switched to the four-wheel drive lock mode is created in advance and the two-wheel drive mode is set. The hydraulic switch 134 turns on the detection signal S _A3 when switching to the four-wheel drive lock mode.
To output as, ie, clutch pressure Pc
The temperature of the hydraulic oil can be easily estimated by measuring the time until the pressure reaches a predetermined pressure and estimating the temperature of the hydraulic oil from the correspondence table based on the measured elapsed time.

Therefore, the temperature can be estimated according to the elapsed time, and the oil temperature can be estimated by diverting the hydraulic switch that has been conventionally arranged. Since it is not necessary to provide an oil temperature sensor, a space can be secured for that amount, and the cost associated with the arrangement of the oil temperature sensor can be reduced.

Further, although there is a temperature range in the estimated temperature of the hydraulic oil estimated from the operating time, the controller 18 requires an accurate oil temperature, for example, switching maps for each temperature based on the estimated oil temperature. Since it has not been done, there is no effect even if the estimated oil temperature has a temperature range. In addition, in the correction coefficient calculation process, the correction coefficient K _D is set based on the estimated hydraulic oil temperature and the operating time of the hydraulic pressure supply circuit 16, so that the operating time of the hydraulic pressure supply circuit 16 varies. The duty ratio D can be corrected according to the change in the viscosity of the hydraulic oil.

In the above embodiment, the case where the hydraulic pressure switch determines whether or not the clutch pressure Pc has reached the predetermined pressure has been described, but not limited to the hydraulic switch, a hydraulic sensor may be applied. . In the above embodiment, the case where the hydraulic oil temperature is estimated based on the time required for the clutch pressure Pc to reach the predetermined pressure has been described. However, for example, the position of the spool of the clutch pressure adjustment valve 122 is detected. When the position sensor is provided and the two-wheel drive mode is switched to the four-wheel drive lock mode, the pilot control pressure from the duty control solenoid valve 128 is input from the state where the spool is biased by the return spring 122a. Thus, by detecting the time from when the spool ascends in FIG. 5 until it returns to the state in which it is biased only by the return spring 122a, the operating speed of the spool due to the change in hydraulic pressure is measured, and the valve operation is performed. The speed is determined to some extent according to the temperature of the hydraulic oil, so the oil temperature is estimated based on this operating speed. It is also possible.

Further, for example, the clutch pressure adjusting valve 122
It is also possible to estimate the hydraulic fluid temperature by detecting the moving speed of the spool by detecting the expansion / contraction state of the return spring 122a of FIG. Further, in the above embodiment, the case where the correspondence table is created and stored in the storage device in advance and the operating oil temperature is estimated from the correspondence table has been described, but the present invention is not limited to this, and, for example, a map or the like is formed. It is also possible to store it in advance, or to calculate it by calculation or the like. Similarly, a case has been described in which a characteristic diagram showing the correspondence of the correction coefficient K _D to the elapsed time t and the hydraulic oil temperature T is created in advance, and the correction coefficient K _D is set based on this characteristic diagram. It is also possible to calculate by.

In the above embodiment, the four-wheel drive vehicle based on the rear-wheel drive vehicle has been described, but the present invention is not limited to this, and the four-wheel drive vehicle based on the front-wheel drive vehicle is also possible. Can also obtain the same effect. Further, in the above embodiment, the torque transmission ΔT is applied to the front wheels based on the difference in the rotational speeds of the front and rear wheels, that is, the difference in the rotational speeds of the front and rear wheels so that the four-wheel drive state is achieved. It is also possible to detect the longitudinal acceleration of the vehicle instead of the rotational speed difference, and to shift from the two-wheel drive state to the four-wheel drive state at the time of sudden start or sudden acceleration.

Further, in the above embodiment, the case where the microcomputer is applied as the controller 18 has been described, but instead of this, electronic circuits such as a counter and a comparator may be combined and configured. Further, in the above embodiment, the case where the chain drive transmission type transfer is applied has been described. However, for example, a drive mechanism is transmitted by disposing a gear mechanism between the input shaft and the output shaft. It is also possible.

Further, in the above embodiment, the case where the transfer having the auxiliary transmission mechanism is applied has been described, but the same effect can be obtained even in the transfer having no auxiliary transmission mechanism. Further, in the above embodiment, in the setting of the correction coefficient K _D in FIG. 14, the case has been described where to set the correction coefficient K _D based on the elapsed time since the estimated hydraulic oil temperature, hydraulic oil temperature It is also possible to set the correction coefficient K _D in accordance with the travel distance after estimating, and the rise of the hydraulic oil temperature is caused by friction etc. of the hydraulic oil being stirred as the vehicle travels. Therefore, since the correction coefficient K _D is set according to the actual traveling distance, it is possible to set the correction coefficient K _D with higher accuracy.

[0101]

As described above, according to the first aspect of the present invention.
According to the above fluid pressure control device, in general, the viscosity of the working fluid depends on its temperature, and the change amount and the rate of change of the fluid pressure are also related to the viscosity of the working fluid. A desired control pressure is output by operating the fluid pressure operating valve to control the fluid pressure. At this time, the fluid temperature estimation means corresponds to the fluid pressure change state of the control pressure detected by the fluid pressure change detection means. By estimating the working fluid temperature as the temperature of the working fluid at the present time, the temperature of the working fluid can be easily estimated without providing a temperature sensor for measuring the temperature of the working fluid.

According to the fluid pressure control device of the present invention, the operating speed of the valve of the fluid pressure operated valve is detected as the fluid pressure change detection means, and the pressure change amount or change rate of the working fluid and the working fluid are detected. From the correlation with the temperature, for example, the correspondence table showing the correspondence between the fluid pressure change state consisting of the operating speed and the working fluid temperature is referred to, and the working fluid temperature corresponding to the operating speed detected by the fluid pressure change detecting means is searched. However, the temperature of the working fluid can be easily estimated by using the retrieved working fluid temperature as the current estimated temperature of the working fluid.

According to the fluid pressure control device of the third aspect, the fluid pressure control means operates the fluid pressure actuating valve to control the fluid pressure, thereby changing the fluid pressure from a preset reference pressure to a predetermined pressure. At this time, when the fluid pressure detecting means detects that the fluid pressure has reached a preset predetermined pressure, the fluid temperature estimating means determines the pressure change amount or change rate of the working fluid and the working fluid temperature. From the correlation of, for example, the correspondence table showing the correspondence between the fluid pressure change state consisting of the required time and the working fluid temperature is referred to, the working fluid temperature corresponding to the required time detected by the required time detecting means is searched, and this is operated. The temperature of the working fluid can be easily estimated by using the estimated temperature of the fluid.

Further, according to the fluid pressure control device of the fourth aspect, by using the hydraulic switch as the fluid pressure detecting means, in the fluid pressure control device having the hydraulic switch, the information of the hydraulic switch already provided can be obtained. By diverting, the hydraulic oil temperature can be easily estimated without adding a sensor or the like.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a fluid pressure control device according to the present invention.

FIG. 2 is a configuration diagram showing an outline of a driving force transmission device of a four-wheel drive vehicle to which the fluid pressure control device according to the present invention is applied.

FIG. 3 is a diagram showing an internal structure of a transfer according to the present invention.

FIG. 4 is an explanatory diagram for explaining the operation of the shift sleeve.

FIG. 5 is a block diagram showing a configuration of a hydraulic pressure supply circuit.

FIG. 6 is an explanatory diagram for explaining the operation of the pilot switching valve.

FIG. 7 is a block diagram showing a configuration of a controller.

FIG. 8 is a characteristic diagram showing a correspondence between a rotational speed difference ΔN and a transmission torque ΔT to the front wheel side.

FIG. 9 is a characteristic diagram showing a correspondence between a clutch pressure P _C and a transmission torque ΔT to the front wheel side.

FIG. 10 is a characteristic diagram showing a correspondence between a duty ratio D and a clutch pressure P _C.

FIG. 11 is a flowchart showing a processing procedure of driving force distribution control processing.

FIG. 12 is a flowchart showing a processing procedure of correction coefficient calculation processing.

FIG. 13 is a correspondence table showing a correspondence between an operating time (count value t1) and a hydraulic oil temperature (estimated oil temperature T).

FIG. 14 shows a hydraulic oil temperature T and an elapsed time t (count value t
It is a characteristic diagram showing correspondence with 2).

[Explanation of symbols]

 10 engine 16 hydraulic supply device 18 controller 22 transfer 40 transfer casing 66 wet multi-plate friction clutch (friction clutch) 72 chain 90 mode selection switch 94 vehicle speed sensor 100 main pump 102 electric motor 103 motor drive circuit 104 sub-pump 105 oil tank 120 electromagnetic switching Valve 124 Pressure reducing valve 126 Pilot switching valve 128 Duty control solenoid valve

Claims (4)

[Claims] 1. A fluid pressure control device comprising a fluid pressure actuated valve and a fluid pressure control means for actuating the fluid pressure actuated valve to output a desired control pressure, the fluid pressure detecting a change state of the control pressure. Based on the fluid pressure change state detected by the fluid pressure change detection means when a predetermined pressure control is performed by the change detection means and the fluid pressure control means, the working fluid temperature corresponding to the fluid pressure change state is calculated based on the fluid pressure change state. A fluid pressure control device comprising: a fluid temperature estimating means for estimating the working fluid temperature. 2. The fluid pressure change detecting means detects a change state of the fluid pressure by detecting an operating speed of a valve of the fluid pressure operating valve, and the fluid temperature estimating means detects the operating speed and the operating fluid. The fluid pressure control device according to claim 1, wherein a corresponding working fluid temperature is calculated and set from a correlation with a temperature and is estimated as the working fluid temperature. 3. The fluid pressure change detection means detects the fluid pressure whether or not the fluid pressure has reached a preset predetermined pressure, and a reference for presetting the fluid pressure by the fluid pressure control means. A fluid pressure detecting means for detecting a time required to detect that the fluid pressure has reached a predetermined pressure when the fluid pressure is changed from a pressure to a predetermined pressure. When the means has detected that the predetermined pressure has been reached, the corresponding working fluid temperature is calculated and set from the correlation between the required time and the working fluid temperature, and this is estimated as the working fluid temperature. 1. The fluid pressure control device according to 1. 4. The fluid pressure control device according to claim 3, wherein the fluid pressure detection means is a hydraulic switch.