JPH01226441A - Clutch control device for drive system for vehicle - Google Patents

Abstract

PURPOSE:To enable prevention of overheating of a friction clutch by a method wherein increase and decrease of clutch torque is controlled so that a clutch heat generating amount is kept at a value lower than the allowable value. CONSTITUTION:A control unit 27 determines a difference Nreal between front and rear wheel rotation speeds by means of a front wheel rotation speed sensor 31 and a rear wheel rotation speed sensor 32 to calculate a target clutch torque T* responding to the Nreal. When a clutch heat generating amount 0(= T*XNreal) exceeds a given allowable value, command clutch torque to a hydraulic control device 20 is gradually increased. Thereafter, when the detected clutch heat generating amount 0 is returned to a value in an allowable value, command clutch torque is increased or decreased so that a clutch heat generating amount is kept at a value lower than an allowable value. This constitution prevents overheating of a multidisc friction clutch 60.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is used as a driving force distribution control device for a four-wheel drive vehicle or a differential limiting control device for a differential mechanism between left and right drive axles or between front and rear drive axles. The present invention relates to a vehicle drive system clutch control device.

(Prior Art) Conventionally, as a clutch heat generation suppression control of a vehicle drive system clutch control device, the control described in, for example, Japanese Patent Application Laid-open No. 175223/1983 is known.

This conventional device detects the amount of heat generated by the clutch, and if the detected amount of heat exceeds an allowable value, the friction member of the clutch is Clutch fastening control is performed to reduce the amount of mutual slippage to zero, thereby suppressing subsequent heat generation due to slipping friction.

Note that the amount of heat generated by the clutch is calculated by multiplying the rotational speed difference between the input and output shafts and the transmitted torque.

(Problem to be Solved by the Invention) However, in such conventional clutch heat generation suppression control, it is possible to determine whether to start clutch engagement/fixing control by detecting the clutch heat generation amount, but if the heat generation amount exceeds an allowable value, Since clutch fastening control is entered in which the amount of slippage between the friction members at the clutch and edge is zero, the clutch heat generation amount during this control is calculated to be zero (based on the rotational speed of the input and output shafts), and the control is canceled. Judgments cannot be made based on detection of the amount of heat generated by the clutch. Therefore, in this conventional example, in order to determine whether the control is to be released, an accelerator OFF sensor is newly added, and the clutch fastening/fixing control is released when the accelerator is OFF.

In other words, the addition of the accelerator FF sensor is disadvantageous in terms of cost, and as long as the accelerator is not turned off, the clutch remains engaged and fixed even if the clutch heat generation is sufficiently suppressed, and variable control of the transmitted torque is prohibited. The problem was that the condition continued for a long time and that tight corner braking occurred in four-wheel drive vehicles.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this purpose, the present invention includes the following:
The method described below was adopted.

The means for solving the problem of the present invention includes a friction clutch which is provided at a position where engine driving force can be distributed to the front and rear wheels or left and right wheels, and which is engaged by external clutch torque; In a vehicle drive system clutch control device comprising a clutch torque control means for controlling increase/decrease of the clutch torque based on input information and control contents, the clutch torque control means includes a clutch for detecting a heat generation amount of the friction clutch. It has a heat generation amount detection section, and when the clutch heat generation amount detected by the clutch heat generation amount detection section exceeds the allowable value, the clutch torque is gradually increased, and then the detected clutch heat generation amount increases to the allowable value. The clutch torque increase/decrease control is performed so that the clutch heat generation amount is maintained below the allowable value when the clutch torque returns to within the range.

(Function) When the clutch heat generation amount detected by the clutch heat generation amount detection section is below the allowable value, the clutch torque control means performs normal control to obtain the optimum front and rear wheel drive force distribution ratio and differential limiting force. Clutch torque increase/decrease control is performed.

When the clutch heat generation amount detected by the clutch heat generation amount detection section exceeds the allowable value, the clutch torque control means gradually increases the clutch torque to suppress the heat generation amount of the friction clutch, and then the clutch heat generation amount is increased. When the clutch torque returns to within the allowable value, the clutch torque is controlled to increase or decrease so that the clutch heat generation amount remains below the allowable value.

Therefore, since the amount of heat generated can always be detected by controlling the increase/decrease of the clutch torque, there is no need to add an accelerator OFF sensor, etc., which is advantageous in terms of cost. In a four-wheel drive vehicle, tight corner braking does not occur, and overheating of the friction clutch can be prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

In describing this embodiment, a driving force distribution control device for a four-wheel drive vehicle will be taken as an example.

First, the configuration will be explained.

The drive system of a four-wheel drive vehicle to which the driving force distribution control device of the embodiment is applied is as shown in FIG. Transmission 2. Transfer input shaft 3. Transfer clutch device A, rear propeller shaft 4. Rear differential 5. Rear wheel 6, transfer output shaft 7. Front propeller shaft8. Front differential9. It is equipped with a front wheel 10, and the engine driving force that has passed through the transmission 2 is directly transmitted to the rear wheel, and is transmitted to the front wheel 10 via a transfer clutch device C provided between the transfer input and output shafts 3 and 7. be done.

And, outside the transfer clutch device C,
A hydraulic control device 20 is provided as a clutch torque control means for producing a control hydraulic pressure Pc serving as a clutch torque based on predetermined input information and control contents.

This hydraulic control device 20 includes a motor 22 that is driven or stopped by a relief switch 21, a hydraulic pump 24 that is operated by the motor 22 to suck water from a reservoir tank 23, and a pump discharge pressure (-next pressure) from the hydraulic pump 24. It is equipped with an accumulator 26 that stores oil via a check valve 25, and an electromagnetic proportional pressure valve 28 that adjusts the line pressure (secondary pressure) from the accumulator 26 to a predetermined control oil pressure Pc using a control current i from a control unit 27. , the control hydraulic pressure port 3 after passing through the control hydraulic vibrator 29
0.

The control unit 27 has an electronic control circuit configuration, and includes a front wheel rotation speed sensor 31, a rear wheel rotation speed sensor 32, etc. as information human power sensors, and in a normal case, for example,
According to the torque characteristics shown in Fig. 3, the target clutch torque T* can be obtained according to the front and rear wheel rotational speed difference N real, that is, the control can obtain the optimal front and rear wheel drive force distribution ratio according to the driving condition. However, the clutch heat generation amount Q (=T” XNreal) obtained by calculation detection
When the value exceeds 〇 to a predetermined tolerance value, the command clutch torque T gradually increases. After that, the detected clutch heat generation amount Q becomes the allowable value A. If the clutch returns to within
The commanded clutch torque Tc is kept below the allowable value A0.
Clutch heat generation control is performed to increase or decrease the clutch friction clutch 60 and prevent the multi-disc friction clutch 60 from overheating.

As shown in FIG. 2, the transfer clutch device C includes a multi-disc friction clutch 6 that is engaged by a pressing mechanism 40 operated by a control hydraulic pressure Pc from an external hydraulic control device 2o.
0, and a lubrication pump 70 that is provided on the transfer input shaft 3 side and sucks up the lubricating oil 15 for cooling the clutch in the transfer case 11 and case cover 12 and guides the lubricating oil 15 to the inner position of the multi-disc friction clutch 60. have.

The pressing mechanism 40 of the multi-disc friction clutch 60 includes a cylinder block 41, a piston chamber 42, a piston 43,
Piston rod 44, swing plate 45, swing pin 46
, a fixed pressure plate 47, a bearing 48, a rotating pressure plate 49, a pressure block 50, and a return spring 51.

The multi-plate friction clutch edge 60 is connected to the transfer input shaft 3
A clutch drum 61 spline-coupled to the clutch drum 61, a drive plate 62 spline-fitted to the clutch drum 61 side, a driven plate 63 sandwiched between the drive plates 62, and a spline-fitted driven plate 63, A clutch hub 65 rotatably supported by a needle bearing 64 is provided for the transfer input shaft 3.

The drive torque is transmitted from the clutch hub 65 to the transfer output shaft Y via the first sprocket 66 → chain 67 → second sprocket 68.

The lubrication pump 70 is of a trochoid pump type and is provided in the pump housing Y1 and the pump cover 72 at the inlet of the transfer input shaft 3, and its suction port 73 communicates with a suction tube 75 having the suction lower 4. , the discharge port 76 communicates with a radial oil passage 77, an axial oil passage 78, and a radial oil passage 79 formed in the transfer input shaft 3 and an oil chamber 80.81 formed in the clutch hub 65. The lubricating oil 15 for clutch cooling inside the case 11 is sucked up, guided to the multi-disc friction clutch 60, and discharged from the oil chamber 82.

The clutch cooling lubricating oil 15 stored in the lower part of the transfer case 11 has a transfer input shaft 3.
A transfer output shaft 7 and a chain 67 for the front wheels 10, which are provided offset from each other, are immersed therein, and a suction lower 4 of a lubricating pump γ0 is arranged.

In addition, in Fig. 2, 90 is the joint flange, 91°92.93
94, 95, 96, 97° 98 are bearings.

Next, the effect will be explained.

First, the flow of the clutch torque control processing operation performed by the control unit 27 of the first embodiment corresponding to claims 1 and 2 will be described with reference to the flowchart of FIG.

In step 101, normal control is performed to obtain a target clutch torque T* corresponding to the front and rear wheel rotational speed difference N real, that is, to obtain an optimal front and rear wheel drive force distribution ratio according to the driving condition.

Note that the target clutch torque T* is the difference in rotational speed between the front and rear wheels N
It is determined from real using the following calculation formula.

T*= f (Nreal) (Figure 3) N
real=l N r-N fl In step 102, it is determined by QFLG whether the clutch heat generation protection logic is currently operating. And 0FLO>O
(= 1), the protection logic is in operation and the process proceeds to step 115, but QFLG≦0 (=0
), the protection logic is not in operation, so the process proceeds to step 103 and subsequent steps.

In step 103, the time elapsed since the previous clutch heat generation protection logic was completed is counted. A counter is incremented.

In step 104, the clutch heat generation amount Q is calculated as the product of the target clutch torque T* and the front and rear wheel rotational speed difference N real.

0=T*XNreal In step 105, the clutch heat generation amount Q is the allowable value A. It is determined whether the

The clutch heat generation amount Q is the allowable value A. In the following cases (Q≦8), the clutch heat generation amount Q is the allowable value A in step 114. Q to count the time since exceeding
. The N□ counter is cleared, and further, in step 112, the target clutch/edge torque T* is set as the command clutch torque T. As a result, the control current i adjusted to the control oil pressure Pc that provides this commanded clutch torque Tc is applied to the electromagnetic proportional pressure valve 2.
8 is output.

Also, in the judgment at step 105, the clutch heat generation amount Q or the allowable value A. If it is larger (Q>A), the process proceeds to step 106 and subsequent steps.

In step 106, Q. The counter is checked.

Then, Q ENI) < A a, and Q END
If the value of the counter is smaller than the set value A4, it is determined that the clutch heats up again immediately after the previous heat generation and there is not enough heat capacity, and the process jumps to step 109 to immediately increase the clutch torque.

Also, Q END≧A4, so Q is good. If the value of the counter is equal to or greater than the set value A4, the heat capacity of the clutch is sufficient, so the process waits for the set time A in steps 107 and 108.゛In step 107, Q
CN□ is incremented.

In step 108, it is determined whether the value of 00□ is greater than the set time A1.

And if OCNT > A +, step 1
The process proceeds from step 09 to step 113, and in step 113, the protect torque T is applied. As the command clutch torque Tc,
This command clutch torque T. A control current j is output to the electromagnetic proportional pressure valve 28 to adjust the control oil pressure Pc to obtain the control oil pressure Pc.

If OCNT≦A, the process proceeds to step 112 where output is performed under normal control.

In step 109, the protect torque T0 calculated by the clutch heat generation protection logic is calculated based on the command clutch/edge torque 'Tea' of one control cycle before.

T o = Tco + A 2 A 2 ; At the set value step 111, 1 is put in Q F L (, to clearly indicate that the clutch heat generation protection logic is in operation.

In step 111, the target clutch torque T* and the protect torque T0 are compared in magnitude, and the larger one is set as the command clutch/edge torque Tc.

To＞To　　　　　　　　　　　　;Tc”T.

T0≦T*: TC=T'4' and above are clutch heat generation detection processing and initial operation processing.

Next, the operation processing while the clutch heat generation protection logic is activated will be explained.

In step 102, if Q FLG = 1, the process proceeds to step 115 and subsequent steps.

In step 115, the clutch heat generation ff1Q is the commanded clutch torque T of one control period before. . (currently applied clutch torque) and front and rear wheel rotational speed difference Nreal.

Q = T coX N real In step 116, it is determined whether the clutch heat generation amount Q is larger than the allowable value.

If Q > A o, the process proceeds to step 117 in order to increase the clutch torque, and in step 117, an increase in the protect torque T0 is calculated.

T o = T co + A t A 2 : Set value After that, jump to step 111 and set the protect torque T
Step 1 is the larger of 0 and target clutch torque T*.
12 or step 113.

If Q≦8, the process proceeds to step 118 in order to reduce the clutch torque, and in step 118, a reduction in the protect torque T0 is calculated.

T o =Tco A 3 A 3; Set value Next, proceed to step 119, and target clutch torque T*
A comparison is made between the protection torque T0 and the protection torque T0.

If T*≦To, proceed to step 113 and apply the protect torque T. is output as the command clutch torque Tc.

In the case of To>To; when Q≦AO (step 116) and the clutch heat generation protection logic activation release condition of To>70 is satisfied, the process proceeds to step 120, and the clutch/edge heat generation protection logic ends. do.

In step 120, OFLG I QCNT * Q
Each ENO is cleared.

Next, the clutch torque control action in the first embodiment will be described.

(b) When the protection logic is not operating and Q≦A, if the clutch heat generation protection logic is not operating and the clutch heat generation amount Q is below the allowable value, step 101→Step 1
02 → Step 703 → Step 104 → Step 10
The control operation flow proceeds from Step 5 to Step 114 to Step 112, and the control unit 27 sets the command clutch torque T by normal control that provides the optimum front and rear wheel drive force distribution ratio according to the target clutch torque characteristics shown in FIG. Increase/decrease control is performed.

(b) When Q>Ao, the clutch heat generation amount Q is the allowable value A. If it exceeds the clutch torque, the clutch clutch heat generation protection logic is activated, and the control unit 27 gradually increases the command clutch torque T by the protect torque T0 to which the set value A is added.
. (steps 109 and 117),
The amount of heat generated by the multi-disc friction clutch 60 is suppressed. After that, when the clutch heat generation amount Q returns to the allowable value within 〇, command the clutch torque T to keep the clutch heat generation amount Q within the tolerance value 〇 or less. An increase/decrease control is performed (steps 117 and 118).

Then, if the conditions ○≦Ao and T*>To are satisfied, the clutch heat generation protection logic is deactivated.

(c) At the time of reheating, through the processing of steps 106 to 109, the clutch heat generation amount Q reaches the allowable value A again within the set time A4. If the clutch torque Tc is exceeded, the commanded clutch torque Tc is immediately increased. However, if heat is generated after the clutch heat generation 'NO has been within the allowable value for the set time A4 or more, the commanded clutch torque Tc is increased for the set time A1. An increase is expected.

As explained above, the driving force distribution control device of the first embodiment provides the following effects.

■ Commanded clutch torque T. The calorific value Q is controlled by the increase/decrease of
Detection is possible at all times, so there is no need to add an accelerator OFF sensor, etc., which is advantageous in terms of cost.In addition, the prohibited state of variable transmission torque control continues for a long time, which prevents the tight corner braking phenomenon in four-wheel drive vehicles. will not occur,
Overheating of the multi-disc friction clutch 60 can be prevented.

- When reheating occurs, the commanded clutch torque Tc is controlled to increase according to the thermal capacity margin of the multi-disc friction clutch 60, so when there is no thermal capacity margin, the commanded clutch torque Tc is increased immediately. While ensuring protection from heat generation in the multi-disc friction clutch 60 by increasing the amount of heat generated by the multi-disc friction clutch 60, when there is sufficient heat capacity, the clutch torque can be increased by waiting for the set time A and the increase in the height command clutch torque To. The operating time of the clutch heat generation protection logic is shortened, and the normal control operating time can be maintained for a long time.

Next, the flow of the clutch torque control processing operation performed by the control unit 27 of the second embodiment corresponding to claims 1 and 3 will be described with reference to the flowchart of FIG.

This second embodiment is an example in which the allowable clutch heat generation value at the time of reheating is gradually reduced.

In step 205, the QEND counter is checked.

Then, if Q END≦A4 and the fever relapses within the set time A4, the heat generation tolerance value Qx is determined from step 208 onwards.
Control by changing to a small value.

In step 208, as a measure against relapse, for example, in the case of relapse, if the allowable value is 172, the current calorific value Q is compared with 1/20.

When Q≦1/2Q x: Target clutch torque T* is set to command clutch torque T in step 214 without reheating. The output is closed.

In the case of Ow+/2QX: It is determined that fever has relapsed, and the heat generation tolerance value Qx is decreased in step 209.

QX=l/2Q, ≧A s A s : set value In addition, in step 205, Q END > A a,
If the 0ENO counter is equal to or greater than the set time A4, it is determined that the cooling has been sufficient and the allowable heat generation value Q is set in step 206.
x to A. shall be.

The other steps are the same as those in the first embodiment shown in FIG. 4, so their explanation will be omitted here.

Therefore, in this second embodiment, in addition to the above effect (2),
The following effects can be obtained.

(2) When the clutch heats up repeatedly in a short period of time, the heat generation allowable value Qx is controlled to be small, so that the clutch can be cooled sufficiently even when the heat capacity margin of the clutch is low.

Next, the flow of the clutch torque control processing operation performed by the control unit 27 of the third embodiment corresponding to claims 1 and 4 will be described with reference to the flowchart of FIG.

This third embodiment is an example in which the logic constant is changed depending on the lateral acceleration Y9.

In step 302, lateral acceleration Y9 is read by a lateral acceleration sensor or the like.

In step 303, each variable is calculated based on the lateral acceleration Y9.

・Clutch increase setting value △Tp ΔT P= f (Y9) = A 2°/Y9, that is,
ΔTp is decreased as Y9 increases.

・Clutch reduction setting value ΔTN ΔTN = f (Y9) = A3°/Y9, that is, Y
As 9 increases, ΔTN decreases.

The above-mentioned ΔTp and ΔTN reduce the range of change in clutch torque, thereby reducing the influence on vehicle behavior and making it smooth.

・Waiting time Wt until clutch torque is increased after detecting heat generation
ime Wtime= f (Y9) = A I'XY(] In other words, increase Wtime as Y9 increases, lengthen the time to wait for the clutch torque to increase, and increase the torque to the vehicle when the vehicle is at its turning limit. This makes it difficult for the influence of

The clutch increase set value ΔTp affects steps 311 and 319, the clutch decrease set value ΔTN affects step 320, and the waiting time Wtime affects step 310.

The other steps are the same as those in the first embodiment shown in FIG. 4, so their explanation will be omitted here.

Therefore, in this third embodiment, in addition to the above effect (■),
The following effects can be obtained.

■ Since the logic constant is changed depending on the lateral acceleration Y9, if the lateral acceleration Y9 is large, the command clutch torque T is changed. By gradually increasing the amount, sudden strong understeer can be prevented.

In other words, in the case of a sharp turn on a dry road, if the clutch torque suddenly increases, strong understeer suddenly occurs, which is dangerous.

Moreover, when the lateral acceleration Y9 is small, the command clutch torque T. By increasing rapidly, the multi-disc friction clutch 600 can be protected from heat generation.

In other words, when driving straight ahead with a small lateral acceleration Y9, a sudden change in clutch torque has no effect on vehicle behavior, and when turning on a low μ road, the clutch torque is already large, and furthermore,
Even if the clutch torque is increased, the change in vehicle behavior is small.

Although the embodiment has been described above based on the drawings, the specific configuration and control contents are not limited to this embodiment.

For example, in the embodiment, an example of application to a driving force distribution control device for a four-wheel drive vehicle was shown, but the present invention can also be applied to a differential limiting control device for left and right wheels or front and rear wheels.

(Effects of the Invention) As described above, in the vehicle drive system clutch control device of the present invention, the clutch torque control means includes a clutch heat generation amount detection section that detects the heat generation amount of the friction clutch, When the clutch heat generation amount detected by the clutch heat generation amount detection section exceeds the allowable value, the clutch torque is gradually increased, and then, when the detected clutch heat generation amount returns to within the allowable value, the clutch heat generation amount is increased. Since this is a means of controlling the increase/decrease of clutch torque to maintain it below the allowable value, it is possible to always detect the amount of heat generated, and there is no need to add an accelerator OFF sensor, etc., which is advantageous in terms of cost. The control inhibition state does not continue for a long time, and tight corner braking does not occur in four-wheel drive vehicles, and the effect is that overheating of the friction clutch can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a drive system and control system of a four-wheel drive vehicle to which a driving force distribution control device according to an embodiment of the present invention is applied, and FIG. 2 is a sectional view showing a transfer clutch device used in the embodiment device. Fig. 3 is a target clutch torque characteristic diagram, Fig. 4 is a flowchart showing the flow of clutch torque control operation in the control unit of the first embodiment, and Fig. 5 is clutch torque control in the control unit of the second embodiment. FIG. 6 is a flowchart showing the flow of the clutch torque control operation in the control unit of the third embodiment. C...Transfer clutch device 1...Engine 2...Transmission 3...Transfer input shaft 7...Transfer output shaft 20...Hydraulic control device (clutch torque control means) 60...Multi-plate Friction clutch (friction clutch)

Claims (4)

[Claims] (1) A friction clutch that is installed at a position where engine driving force can be distributed to the front and rear wheels or left and right wheels and that is engaged using external clutch torque; and a friction clutch that is installed outside of the friction clutch and that provides predetermined input information and control content. In the vehicle drive system clutch control device, the clutch torque control means includes a clutch torque control means for controlling increase/decrease of the clutch torque based on the clutch torque, wherein the clutch torque control means includes a clutch heat generation amount detection section that detects the heat generation amount of the friction clutch. If the clutch heat generation amount detected by the clutch heat generation amount detector exceeds the allowable value, the clutch torque is gradually increased, and then, when the detected clutch heat generation amount returns to within the allowable value, the clutch torque is increased. A vehicle drive system clutch control device, characterized in that it is a means for controlling increase/decrease in clutch torque so that the amount of heat generated is kept below a permissible value. (2) The clutch torque control means immediately increases the clutch torque if the clutch heat generation exceeds the allowable value again within the set time, but if the clutch generates heat after the clutch heat release has been within the allowable value for more than the set time. 2. The vehicle drive system clutch control device according to claim 1, wherein the control device performs control for waiting for an increase in clutch torque for a set time from the point in time when the amount of heat generated exceeds an allowable value. (3) The clutch torque control means is a means for performing control such that when the clutch heat generation amount exceeds the allowable value and then returns to within the allowable value, the allowable value of the clutch heat generation amount is reduced within a set time after the return. The vehicle drive system clutch control device according to claim 1 or 2. (4) The clutch torque control means is a means for performing control such that a clutch torque control constant changes according to lateral acceleration, and as the lateral acceleration increases, the clutch torque increases and decreases per unit time. A vehicle drive system clutch control device according to claim 1, claim 2, or claim 3.