JPH0825399B2 - Vehicle drive system clutch control device - Google Patents

Description

The present invention relates to a vehicle used as a driving force distribution clutch of a transfer device of a four-wheel drive vehicle and a differential limiting clutch of a differential device provided between left and right wheels. The present invention relates to a drive system clutch control device.

(Prior Art) As a conventional drive force distribution control device for a four-wheel drive vehicle, for example, a device described in JP-A-61-157437 is known.

This conventional device calculates the rotational speed difference between the front and rear wheels based on the sensor signals from the front and rear wheel rotational speed sensors, and the larger the difference between the front and rear wheel rotational speeds, that is, the larger the occurrence of the drive wheel slip, the engagement of the transfer clutch. It is intended to increase the force and change the distribution of the driving force to the four-wheel driving side to promptly suppress the driving wheel slip.

(Problems to be Solved by the Invention) However, in such a conventional device, the clutch engagement force control law (control characteristic) with respect to the front-rear wheel rotation speed difference is uniquely determined, so However, there remains a problem that the control software cannot always sufficiently cope with changes in the friction coefficient of the road surface and various hardware changes of the vehicle to which the control device is applied.

For example, if you set a control law (characteristic that does not distribute a large amount of driving force to the front wheels) on a dry good road, driving stability and stack escapeability on a low friction coefficient road such as an ice and snow road will become insufficient. I will end up.

Further, if the control law is unambiguously determined, a similar tendency is exhibited depending on the degree of wear of the tire, the change over time of the multi-plate clutch, the temperature condition of the transfer unit, and the like.

On the other hand, as described in the conventional publication, there is a plan to change the control constant of the control characteristic by the road surface friction coefficient, but it is practically impossible to directly detect the road surface friction coefficient.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and in order to achieve the object, the present invention has the following solution means. did.

The solution means of the present invention will be described with reference to the conceptual diagram of the claims shown in FIG. 1. The solution is provided in the middle of an engine drive system for distributing and transmitting the engine drive force to the front and rear wheels or the left and right wheels, and the transmission torque of the transmission torque is increased by the clutch engagement force from the outside. A slip generation state detection unit 401 that detects the slip generation state of the normal drive wheels based on input signals from the drive system clutch means 1 that can be changed, the front wheel rotation speed sensor 2 and the rear wheel rotation speed sensor 3.
And a clutch control unit 4 having the drive system clutch unit 1 and an output unit 402 for outputting a control signal for controlling the engagement force according to the slip occurrence state from the detection unit 401, and a vehicle drive system including In the clutch control device, the clutch control means 4 includes a slip occurrence state detection unit 401.
A slip occurrence frequency detector 403 for detecting the slip occurrence frequency of the normal driving wheels by monitoring the detection signal from
It is characterized in that a control law changing unit 404 is provided for changing the clutch engagement force control law to have a higher engagement force level as the slip occurrence frequency from 03 increases.

(Operation) In the vehicle drive system clutch control device of the present invention, as described above, the slip occurrence frequency detection unit that detects the slip occurrence frequency of the normal drive wheels by monitoring the detection signal from the slip occurrence state detection unit is provided. As a measure, this slip occurrence frequency brings very rich input information such as the condition of the road surface, the condition of the tires, the condition of the clutch, and the driving condition.

Therefore, even though it is a simple means that does not use many sensors, the friction coefficient change of the traveling road surface can be changed by changing the clutch engagement force control law to have a higher engagement force level as the slip occurrence frequency increases. It is possible to perform optimal clutch engagement force control corresponding to various hardware changes of the vehicle to which the control device is applied.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In describing this embodiment, a drive force distribution clutch control device for a four-wheel drive vehicle based on rear wheel drive will be taken as an example.

 First, the configuration of the first embodiment will be described.

The four-wheel drive vehicle to which the driving force distribution clutch control device D of the embodiment is applied is, as shown in FIG. 2, a transfer device.
10, engine 11, transmission 12, transfer input shaft 13, rear wheel side drive shaft 14, multi-disc friction clutch (drive system clutch means) 15, rear differential 16, rear wheel 17, front differential 18, front wheel 19, gear train 20, A front wheel side drive shaft 21 is provided.

The transmission 12 shifts the rotational driving force from the engine 11 according to the gear position selected by the shift operation, and in the embodiment, a type in which two parallel shafts are provided with a gear set having different gear ratios. I use the one.

The transfer input shaft 13 is a shaft that inputs the rotational driving force from the transmission 12 to the multi-plate friction clutch 15 in the transfer device 10.

The rear wheel side drive shaft 14 is directly connected concentrically with the transfer input shaft 13, and the rotational driving force from the transfer input shaft 13 is transmitted as it is.

The multi-plate friction clutch 15 is a clutch whose transmission torque can be changed to the front wheel side by the clutch hydraulic pressure, and includes a clutch drum 15a fixed to the transfer input shaft 13 and the rear wheel side drive shaft 14, and the clutch drum 15a. Friction plates 15b rotationally engaged with each other, a clutch hub 15c rotatably supported on the outer peripheral portion of the input shaft 13, and friction discs 15d rotationally engaged with the clutch hub 15c are alternately arranged. Friction plate 15b
A clutch piston 15e provided at one end of the friction disk 15d, and a cylinder chamber 15f formed between the clutch piston 15e and the clutch drum 15a.
It has.

The rear differential 16 and the front differential 18 include left and right rear wheels 17, 17 and left and right front wheels 19, 19
This is a differential device that distributes and transmits the driving force while allowing the differential to occur.

The gear train 20 includes a first gear 20a provided on the clutch hub 15c, a second gear 20c provided on the intermediate shaft 20b, and a third gear 20d provided on the front wheel drive shaft 21.
And means for transmitting the driving force to the front wheels by the engagement of the multi-plate friction clutch 15.

The front-wheel-side drive shaft 21 is a shaft that transmits rotational drive force to the front wheels 19, 19 of the vehicle.

FIG. 4 shows a specific example of the transfer device 10, in which the multi-plate friction clutch 15, gears and shafts are housed in a transfer case 22.

In FIG. 4, 15g is a dish plate, 15h is a return spring, 24 is a clutch pressure oil input port, 25 is a clutch pressure oil passage, 26 is a rear wheel output shaft, 27 is a lubrication oil passage, and 28 is a pinion for a speedometer. , 29 is an oil seal, 30 is a bearing, 31
Is a needle bearing, 32 is a thrust bearing, and 33 is a joint flange.

Next, the driving force distribution clutch control device D of the embodiment, as shown in FIG. 3, is a hydraulic pressure generation device 50 as an external device that generates hydraulic pressure for engaging the multi-plate friction clutch 15, and a hydraulic pressure generation device 50. A hydraulic pressure generator 50 and a hydraulic pressure controller 40 for controlling the hydraulic pressure from the hydraulic pressure generator 50 to a predetermined clutch pressure P are provided.

The oil pressure generating device 50 includes an oil pump 51, a pump oil pressure passage 52, a clutch pressure oil passage 53, a branch drain oil passage 54, a reserve tank 55, and a suction oil passage 56.

The hydraulic control device 40 includes the rotation speed sensor 41 and the rear wheel rotation speed sensor 42 as detection means, a control unit 45 as a control circuit, and a valve solenoid 46a and a check oil passage 46b as control actuators.
The electromagnetic proportional relief valve 46 (provided in the branch drain oil passage 54) having the above is provided.

The front wheel rotation speed sensor 41 and the rear wheel rotation speed sensor 42 are
They are provided in the middle of the front wheel drive shaft 21 and the rear wheel drive shaft 14 and at the positions of the left and right front wheels 19 and 19, etc., and are arranged close to the sensor rotor fixed to the shaft and the sensor rotor to detect magnetic force changes. A rotation speed sensor or the like is used by the pickup sensor and a rotation signal (nf) such as a sine wave signal corresponding to the shaft rotation from the rotation speed sensors 41 and 42.
(Nr) is output.

As the control unit 45, a control circuit centered on a vehicle-mounted microcomputer is used, and the rotation signals (nf) and (nr) from the rotation speed sensors 1 and 42 are input,
Basically, the rotational speed difference ΔN (Nr
-Nf) is calculated, and as the rotational speed difference ΔN increases, the transmission torque ΔT to the front wheels (a command current signal (i) that increases the clutch hydraulic pressure P to bring the driving force distribution closer to the four-wheel driving state).
Is output to the electromagnetic proportional relief valve 46. As shown in FIG. 5, the internal circuit includes an input interface 451, a RAM 452, a ROM 453, a CPU 454, and an output interface 455.

The ROM 454 (read only memory) is a read-only memory, and the ROM 454 has a control law (characteristic A and characteristic B) between the front and rear wheel rotational speed difference ΔN and the command current value ^* as shown in FIG. Is stored and set in advance.

Further, both characteristics are characteristics of the command current value I ^* which gradually increases until the front-rear wheel rotational speed difference ΔN reaches a predetermined value and rapidly increases when it exceeds the predetermined value, and the B characteristic has a command current value I more than the A characteristic. ^*
Is set large.

When the output of the command current signal (i) is the command current value I ^* = 0, the clutch proportional pressure P = 0. However, the output of the command current signal (i) is the command current value I ^*. If> 0, the valve moves in the closing direction, and the pump pressure from the oil pump 51 is set to the clutch pressure P according to the magnitude of the command current value I ^* by drain oil amount control (the sixth pressure).
Figure). The relationship between the clutch pressure P and the transmission torque ΔT to the front wheels is represented by the following equation (FIG. 7).

P = ΔT / (μ ・ S ・ 2n ・ Rm) where μ: Friction coefficient of clutch plate S; Pressure acting area on piston s; Number of friction discs Rm; Effective radius of torque transmission of friction discs Therefore, increase clutch pressure P Then, the transmission torque ΔT to the front wheel side also increases in proportion.

 Next, the operation of the embodiment will be described.

First, the flow of the driving force distribution clutch control operation in the first embodiment will be described with reference to the flowchart shown in FIG.

First, in the first embodiment, the slip occurrence state is detected by the front and rear wheel rotation speed difference ΔN, and this rotation speed difference ΔN is a predetermined value ΔN _0.
The slip occurrence frequency is detected depending on how many times the count number n is within a certain time T _0. If n> n ₀ , the B characteristic is selected, and if n ≦ n ₀ , the A characteristic is selected. In this example, is selected to output the command current signal (i).

First, the counter number n is set to zero (step 10
0), the timer value t is set to zero (step 101), and the front / rear wheel rotational speed difference ΔN (= Nr−Nf) is read (step).
102).

Next, it is judged whether or not the front and rear wheel rotation speed difference ΔN exceeds a predetermined value ΔN ₀ (step 103), and NΔ> ΔN ₀
If so, 1 is added to the count number n (step 10).
Four).

After ΔN ≦ ΔN _{0 in} step 103 or the count number n is set to n + 1 in step 104, the timer value t is added (step 105), and it is determined whether the timer value t exceeds a certain time T _0. If ≦ T ₀ , the flow from step 102 is repeated (step 106).

When it is determined in step 106 that t> T ₀ , the process proceeds to step 107, and the count number n during the fixed time T ₀ is output, and it is determined whether or not the count number n exceeds a predetermined value n _0. (Step 108).

If n> n _{0 in} step 108, the B characteristic is selected (step 109), and the B characteristic and the front and rear wheel rotation speed difference ΔN.
The command current signal (i) is output by and (step
110).

If n ≦ n _{0 in} step 108, the A characteristic is selected (step 111), and the A characteristic and the front and rear wheel rotation speed difference ΔN.
The command current signal (i) is output by and (step
112).

As described above, in the driving force distribution clutch control device D of the first embodiment, the following effects can be obtained.

Since the slip detection state is detected by the front-rear wheel rotation speed difference ΔN and the slip generation frequency of the rear wheel, which is the normal drive wheel, is detected by monitoring the slip generation state, the input sensor is the front wheel rotation speed sensor 41. The slip occurrence frequency can be obtained as input information with a simple configuration including only the rear wheel rotation speed sensor 42.

The above-mentioned slip occurrence frequency brings very abundant input information such as running road surface condition, tire condition, clutch condition, driving condition, etc. When the slip occurrence frequency is high, clutch engagement is performed by the B characteristic of high clutch pressure level. Since the pressure is controlled, it is possible to perform the optimum clutch pressure control in response to changes in the friction coefficient of the traveling road surface and various hardware changes of the vehicle to which the control device is applied.

As the control characteristic, as shown in FIG. 8, the command current value I ^* is gradually increased in the low rotation speed difference region, and the command current value I ^* is rapidly increased in the high rotation speed difference region. It is possible to achieve both the tight corner braking phenomenon prevention effect in the rotational speed difference region and the startability and acceleration improvement effect in the high rotational speed difference region.

Next, a second embodiment device shown in FIGS. 10 and 11 will be described.

The configuration of the device of the second embodiment is similar to that of the first embodiment, and the first embodiment has A characteristics and B characteristics as control characteristics.
In contrast to the example in which two characteristics are set, the 10th
As shown in the figure, the difference is that one characteristic map is set.

The flow of the driving force distribution clutch control operation in the second embodiment will be described with reference to the flow chart shown in FIG.

First, in the second embodiment, the slip occurrence state is detected by the front and rear wheel rotation speed difference ΔN, and this rotation speed difference ΔN is a predetermined value ΔN _0.
The slip occurrence frequency is detected depending on how many times the count number n exceeds a certain time T ₀ , and if n> n ₀ , the maximum command current value I ^* max is output for a predetermined time T 1, n
If ≦ n ₀ , the command current signal (i) based on the characteristic map
Is an example in which is output.

Of the flow of clutch control operation in the second embodiment, steps 100 to 108 are the same as in the first embodiment.

If n> n _{0 in} step 108, the command current signal (i) whose command current value I ^* is the maximum command current value I ^* max is output (step 120). Then, in step 121, the timer value t1 is set to zero, and in step 122, I ^* = I
If it is ^* max, 1 is added to the timer value t1 in step 123, and it is determined in step 124 whether the timer value t1 exceeds the fixed time T1.

That is, the maximum command current value I ^* max is the constant time T1
Will be output only.

If n ≦ n _{0 in} step 108, the characteristic map shown in FIG. 10 is selected, and the command current signal (i) based on the current value I ^* obtained from this characteristic map and the front and rear wheel rotational speed difference ΔN is output. (Step 125).

Therefore, in the second embodiment, in addition to the effects described in the first embodiment, one preset control characteristic map is sufficient, and the memory storage capacity can be small.

Next, the third embodiment device shown in FIGS. 12 to 14 will be described.

The third embodiment differs from the first and second embodiments in that a longitudinal acceleration sensor 43 for detecting the longitudinal acceleration Xg of the vehicle is added as an input sensor (Fig. 12), and the control characteristics are different. Is the same as in the first embodiment.
This is an example of setting two characteristics (Fig. 13).

The flow of the driving force distribution clutch control operation in the third embodiment will be described with reference to the flow chart shown in FIG.

First, in the third embodiment, the rear wheel slip ratio equivalent value S = ΔN /
The slip occurrence state is detected by Nr (the front wheel slip ratio equivalent value S = ΔN / Nf may be substituted), and this value S is the predetermined value S ₀
Is exceeded and the longitudinal acceleration Xg is smaller than the predetermined value Xg ₀ , the slip occurrence frequency is detected depending on how many times the count number n is within a certain time T ₀ , and if n> n ₀ , A In this example, the characteristic is selected, and if n ≦ n ₀ , the B characteristic is selected and the command current signal (i) is output based on each selected characteristic map.

Of the flow of the clutch control operation in the third embodiment, steps 100 to 102 and steps 104 to 112 are the same as in the first embodiment.

In steps 130 and 131, the front wheel rotation speed Nf and the rear wheel rotation speed Nr are read.

At step 132, the rear wheel slip ratio equivalent value S = ΔN / (Nr
+1) is calculated, and this value S is set to a predetermined value S _{0 in} step 133.
If S> S ₀ , the routine proceeds to step 134, and it is determined whether the longitudinal acceleration Xg exceeds a predetermined value g _0. If Xg ≦ Xg ₀ , the routine proceeds to step 104. , And the count number n is added.

That is, in order to add the count number n, S>
Must satisfy both the condition that S is ₀ and and Xg ≦ Xg _0, that is added Xg ≦ Xg _0, when the drive wheel slip occurs due to acceleration operation of the fastest stepping on the accelerator is , The number of counts n is not added, and acceleration is ensured during sports driving.

Therefore, in the third embodiment, in addition to the effect described in the first embodiment, there is no sudden change in the distribution of the driving force during acceleration traveling, and the stability of acceleration traveling is ensured.

The embodiment of the present invention has been described in detail above with reference to the drawings.
The specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope of the present invention, they are included in the present invention.

For example, in the embodiment, the example in which the driving force distribution clutch to the front and rear wheels is controlled has been shown. However, as shown in Japanese Patent Application No. 60-162267, a differential device (differential) provided between the left and right wheels is used. In a vehicle having the same, it can be applied to a differential limiting clutch that limits the differential of the differential device.

Further, the clutch hydraulic pressure control means is not limited to the electromagnetic proportional relief valve of the embodiment, but may be other means, for example, a solenoid on-off valve structure or the like when a duty control signal is used.

Further, in the embodiment, the multi-plate friction clutch by hydraulic engagement is shown as the clutch means, but other clutches such as an electromagnetic clutch and a viscous clutch may be used.

(Effects of the Invention) As described above, in the drive system clutch control device according to the present invention, the clutch control means monitors the detection signal from the slip occurrence state detection unit to determine the slip occurrence frequency of the normal drive wheels. Since the slip occurrence frequency detecting section for detecting and the control rule changing section for changing the clutch engaging force control law to have a higher engaging force level as the slip occurrence frequency from the detecting section increases, the sensor Although it is a simple method that does not use many types, it has the effect of being able to perform optimal clutch engagement force control that responds to changes in the friction coefficient of the road surface and various hardware changes of the vehicle to which the control device is applied. To be

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a vehicle drive system clutch control device of the present invention, FIG. 2 is a diagram showing a four-wheel drive vehicle to which the drive system clutch control device of the embodiment is applied, and FIG. 3 is an embodiment. FIG. 4 is an overall view showing the vehicle drive system clutch control device, FIG. 4 is a sectional view showing a transfer device of the embodiment device, FIG. 5 is a block diagram showing a control unit of the embodiment device, and FIG. 6 is a clutch hydraulic pressure. And FIG. 7 is a characteristic diagram of relation between transmission torque to front wheel side, FIG. 7 is a characteristic diagram of relation between command current value and clutch hydraulic pressure, and FIG. 8 is a command for a front and rear wheel rotation speed difference preset in the control unit of the embodiment apparatus. Fig. 9 is a control characteristic diagram of current value, Fig. 9 is a flow chart showing the flow of drive system clutch control operation in the control unit of the first embodiment device, and Fig. 10 is a control unit of the second embodiment device. The control characteristic diagram of the command current value with respect to the front-rear wheel rotational speed difference that is set for this purpose, FIG. 11 is a flow chart showing the flow of the drive system clutch control operation in the control unit of the second embodiment device, and FIG. Three
FIG. 13 is a block diagram showing a control unit of the embodiment apparatus, FIG. 13 is a control characteristic diagram of a command current value with respect to front and rear wheel rotation speed difference preset in the control unit of the third embodiment apparatus, and FIG. It is a flowchart figure which shows the flow of a drive system clutch control operation | movement in the control unit of 3rd Example apparatus. 1 ... Drive system clutch means 2 ... Front wheel rotation speed sensor 3 ... Rear wheel rotation speed sensor 4 ... Clutch control means 401 ... Slip occurrence state detection unit 402 ... Output unit 403 ... Slip occurrence frequency detection unit 404 ...... Control law change section

Claims (1)

[Claims] 1. A drive system clutch means, which is provided in the middle of an engine drive system for distributing and transmitting engine drive force to front and rear wheels or left and right wheels, and which can change transmission torque by external clutch engagement force, and a front wheel rotation speed sensor. And a slip generation state detection unit that detects a slip generation state of the normal drive wheels based on an input signal from the rear wheel rotation speed sensor, and controls the engagement force of the drive system clutch means according to the slip generation state from the detection unit. And a clutch control means having an output portion for outputting a control signal for controlling a vehicle drive system clutch control device, wherein the clutch control means monitors a detection signal from the slip occurrence state detection portion to normally drive wheels. The slip occurrence frequency detection unit that detects the slip occurrence frequency and the higher the slip occurrence frequency from the detection unit, the higher A drive system clutch control device for a vehicle, characterized in that a control law changing section for changing the engagement force level into a clutch engagement force control law is provided.