JPH0437789Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is used in power split devices such as differentials and transfer devices of four-wheel drive vehicles, and is used to vary differential limiting torque and driving force distribution torque. The present invention relates to a drive system clutch control device for a vehicle.

(Prior Art) Conventionally, as a device for controlling the increase/decrease of differential limiting torque according to predetermined control conditions, for example,
A differential limiting control device as described in Japanese Patent Application No. 61-102321 (Japanese Patent Application No. 59-223487) is known.

This conventional device uses the accelerator opening (also called throttle opening) as an input condition, and increases the differential limiting torque as the accelerator opening increases, and conversely decreases the differential limiting torque as the accelerator opening decreases. It was a device with control contents that allowed

(Problem that the invention aims to solve) However, with such conventional devices, although the differential limiting torque is increased or decreased according to changes in the accelerator opening, the response speed remains constant and the speed suddenly increases. It is not responsive to changes in accelerator opening, and when turning while suddenly releasing the accelerator pedal, the differential limiting torque suddenly drops.
By limiting the differential motion between the left and right wheels, the understeer characteristics that had been obtained were reduced, and the effect of suppressing the tuck-in phenomenon was reduced.

In contrast, in the earlier application, Japanese Patent Application No. 60-284572 (Japanese Unexamined Patent Publication No. 62-143719), the present applicant made the increase/decrease response speed of the differential limiting torque variable in accordance with the accelerator opening change rate. When the accelerator pedal opening suddenly decreases, the clutch is held engaged for a predetermined period of time by slowing down the response speed, thereby suppressing the tuck-in phenomenon that occurs when turning while suddenly releasing the accelerator pedal.

However, even in this earlier application, when suppressing tack-in, the duration of the differential limiting torque was uniquely determined by the return speed (〓) of the accelerator; If the duration of the differential limiting torque is set to a long time, it may be suitable for large radius turns, so-called high-speed turns, but it will be too long for small radius turns, so-called mountain road turns, and the tendency to understeer will be promoted. The problem was that it was difficult to do. On the other hand, if the duration of the differential limiting torque is set to a short time, there is a problem in that a sufficient tuck-in suppressing effect cannot be obtained for large radius turns, so-called high speed turns.

(Means for solving the problems) The present invention was made with the purpose of solving the above-mentioned problems, and to achieve this purpose, the present invention adopted the following solution methods. .

The solution of the present invention will be described with reference to the claim conceptual diagram shown in FIG. A drive system clutch means 4 is provided between the drive output section and the drive output section, and generates a transmission torque by an external control force; an input sensor 5 detects the vehicle condition; A drive system clutch control device for a vehicle is provided with a control means 6 for outputting a control signal to increase or decrease, and the input sensor 5 includes an accelerator opening sensor 501 and a vehicle speed sensor 502, When the speed suddenly decreases, the drive system clutch means 4 is kept in the engaged state for a predetermined period of time, and the clutch engagement duration is made longer as the vehicle speed increases.

(Function) In the vehicle drive system clutch control device of the present invention,
By employing the above-mentioned means, when the accelerator pedal is suddenly released, the engagement state of the drive system clutch means is maintained for a predetermined period of time proportional to the vehicle speed.

Therefore, the optimal clutch engagement duration can be obtained depending on the situation in which tack-in occurs, and when the foot is suddenly released during a large radius turn at high speed, the clutch engagement duration is long, so the clutch engagement duration is long enough. The effect of suppressing tack-in can be obtained, and when the driver suddenly releases his/her foot while turning at low speed in a small radius, the short engagement duration of the clutch prevents the tendency of understeer from being exacerbated and making it difficult to turn.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In describing this embodiment, an example will be taken of a differential limited clutch control device for an automobile equipped with a multi-disc friction clutch means operated by external hydraulic pressure.

As shown in FIGS. 2 to 4, the embodiment device has the following features:
Differential device (power split device) 10, multi-plate friction clutch means (drive system clutch means) 11, hydraulic pressure generator 12, control unit (control means) 1
3. It is equipped with an input sensor 14, and each configuration will be described below.

The differential device 10 has a differential function of providing a speed difference between the left and right wheels in accordance with the rotational speed difference in a driving state where a rotational speed difference occurs between the left and right wheels;
This device has a driving force distribution function that equally distributes and transmits the engine driving force to the left and right drive wheels.

This differential device 10 is housed in a housing 16 that is attached to the vehicle body with stud bolts 15, and includes a ring gear 17, a differential case 18, and a pinion mate shaft 1.
9, differential pinion 20, side gear 21, 21'
It is equipped with

The differential case 18 has a tapered roller bearing 22,
It is rotatably supported by 22'.

The ring gear 17 is fixed to a differential case 18 and is connected to the propeller shaft 2.
3, and rotational driving force is input from this drive pinion 24.

The side gears 21, 21' are respectively provided with a left-wheel drive shaft 25 and a right-wheel drive shaft 26, which are drive output shafts.

The multi-plate friction clutch means 11 is connected to the differential gear 1.
0 between the drive input section and the drive output section,
This is a means for generating differential limiting torque by applying clutch engagement force using external hydraulic pressure.

This multi-plate friction clutch means 11 is housed within a housing 16 and a differential case 18, and includes multi-plate friction clutches 27, 2.
7', pressure ring 28, 28', reaction plate 29, 29', thrust bearing 30, 3
0', spacer 31, 31', push rod 3
2, hydraulic piston 33, oil chamber 34, hydraulic port 3
5.

The multi-plate friction clutches 27, 27' include friction plates 27a, 2 fixed to the differential case (drive input section) 18 in the rotational direction.
7'a and side gear (drive output part) 21, 2
1' and friction disks 27b, 27'b fixed in the rotational direction, and pressure rings 28, 28' and reaction plates 29, 29' are arranged on both end faces in the axial direction. There is.

The pressure rings 28, 28' are provided in a fitted state on the pinion mate shaft 19 as members receiving the clutch fastening force, and the fitting portion has a rectangular cross section as shown in FIG. It is fitted to the shaft end 19a through square grooves 28a, 28'a, and has a structure in which no thrust force is generated due to a rotational difference, unlike the conventional torque proportional differential limiting means.

The hydraulic piston 33 moves in the axial direction (rightward in the drawing) by hydraulic pressure supplied to the hydraulic port 35,
Both multi-plate friction clutches 27, 27' are engaged in accordance with the oil pressure level, and in one multi-disc friction clutch 27, the engagement force is transmitted from the push rod 32 to the spacer 31 to the thrust bearing 30 to the reaction plate 29. , are fastened using the pressure ring 28 as a reaction force receiver, and the other multi-plate friction clutch 27' is fastened using the fastening reaction force from the housing 16 as a fastening force.

As shown in FIG. 4, the hydraulic pressure generating device 12 is an external device that generates hydraulic pressure that becomes the clutch engagement force.
Hydraulic pump 40, pump motor 41, pump pressure oil path 42, drain oil path 43, control pressure oil path 44,
Valve solenoid 4 as valve actuator
5 is provided with an electromagnetic proportional pressure reducing valve 46.

The pump motor 41 is a motor that is activated or deactivated by a motor signal (m) from the control unit 13, and is activated or deactivated when the pump is running and differential restriction is being performed or there is a possibility that differential restriction is being performed. At certain times, a motor signal (m) is output due to energization,
When the differential restriction is not required at all, such as when the vehicle is stopped, a de-energized motor signal (m) is output.

The electromagnetic proportional pressure reducing valve 46 is connected to the hydraulic pump 4
The hydraulic oil at the pump pressure supplied from 0 through the pump pressure oil path 42 is pressure controlled to a control oil pressure P proportional to the magnitude of the control current value i ^* by the control current signal (i) from the control unit 13. It is a valve actuator that sends control hydraulic pressure P from the control pressure oil path 44 to the hydraulic port 35 and oil chamber 34, and the control current signal (i) is output to the valve solenoid 45 of the electromagnetic proportional pressure reducing valve 46. be done.

The control oil pressure P and the differential limiting torque T are in the following relationship: T∝P・μ・n・r・A n; Number of clutches r; Clutch average radius A; Pressure receiving area, and the differential limiting torque T has the following relationship: It is proportional to the oil pressure P.

The control unit 13 uses an in-vehicle microcomputer, and includes an input circuit 131,
RAM (random access memory) 132,
ROM (read only memory) 133,
CPU (Central Processing Unit) 1
35, a clock circuit 135, and an output circuit 136.

Note that the input sensor 14 includes a vehicle speed sensor 14.
1. An accelerator opening sensor 142 is provided.

The input circuit 131 is a circuit that converts the input signals (v) and (a) from the input sensor 14 into signals that can be processed by the CPU.

The RAM 132 is a readable and writable memory, and input signals from the sensors 141 and 142 are written therein, as well as information during calculation by the CPU 134.

The ROM 133 is a read-only memory in which information necessary for arithmetic processing by the CPU 134 is stored in advance, and is read-only from the CPU 13 as necessary.
It is read from 4.

The CPU 134 is a device that performs arithmetic processing on various input information according to predetermined processing conditions.

The clock circuit 135 is a circuit that sets the calculation processing time of the CPU 134.

The output circuit 136 is a circuit that outputs a control current signal (i) to the valve solenoid 45 based on a calculation result signal from the CPU 134.

The vehicle speed sensor 141 is a sensor that detects the vehicle speed of the vehicle and outputs a vehicle speed signal (v) according to the vehicle speed.

The accelerator opening sensor 142 is a sensor that detects the degree of depression of the accelerator pedal and outputs an accelerator opening signal (a) corresponding to the accelerator opening (also referred to as throttle opening).

The vehicle speed sensor 141 and the accelerator opening sensor 142 determine the target control current value i ^* from a control characteristic map preset in the control unit 13.
It is used as a sensor to search for.

In addition, the ROM 13 of the control unit 13
3, a control characteristic map M corresponding to the accelerator opening A and the vehicle speed V is set as shown in ^FIG . It is a map that is a characteristic that can be used.

Next, the operation of the embodiment will be explained.

First, the operation of the embodiment will be described with reference to the flowchart shown in FIG. 6, which shows the operational flow of differential limiting control.

(b) When the accelerator pedal is depressed When operating the accelerator pedal in the direction of depression during starting or acceleration when the accelerator opening degree change rate Å is > 0, step 200 → step 201 →
The operation flow is step 202→step 203→step 204→step 205, and in step 205, a control current signal (i) corresponding to the searched target control current value i ^* and the selected control gradient is output.

Step 200 is a step for reading the vehicle speed V based on the vehicle speed signal (v) from the vehicle speed sensor 141 and the accelerator opening degree A based on the accelerator opening signal (a) from the accelerator opening sensor 142.

Step 201 is a calculation step that calculates the accelerator opening change rate Å based on the current accelerator opening An read in step 200 and the accelerator opening An _-1 read at the previous control activation. .

The calculation formula for the accelerator opening change rate Å is: Å=An−An ₋₁ /t t; control activation time.

Step 202 is a judgment step for determining whether the accelerator opening change rate Å calculated in step 201 is Å≧0.

Step 203 is a selection step in which a control gradient indicating the degree of increase/decrease in the control current signal (i), which has been set in advance by increase or the like, is selected based on the value of the accelerator opening change rate Å.

Step 204 is a search step in which a target control current value i ^* is searched based on the control map M and the vehicle speed V and accelerator opening A read in step 200.

Step 205 is an output step that outputs a control current signal (i) according to the target control current value i ^* retrieved in the step and the control slope selected in the step 203.

As a specific example, when the vehicle speed is zero and the accelerator pedal is slowly depressed (|Å| = small), and the vehicle speed V gradually increases, the target control current value i ^* changes from 0 to 1 based on the control characteristic map M. →2→3 The control current signal (i) changes stepwise as the accelerator opening A and vehicle speed V increase, but the control current signal (i) does not suddenly change step by step, and the absolute value of the accelerator opening speed A | The control current value gradually changes to approach the target control current value i ^* at a rate of change that is slow depending on the magnitude of Å|. Also,
When accelerating by suddenly pressing the accelerator pedal (|Å|=large) from a predetermined medium speed range, the target control current value i ^* increases from 2 to 3 based on the control characteristic map M. At that time, the control current signal (i) changes at a fast rate of change proportional to the depression speed of the accelerator pedal. That is, the control gradient, which is the degree of increase in the control current signal (i), is increased, and the current is output so as to immediately reach the target control current value i ^* .

(b) When the accelerator pedal is released, when the vehicle speed V is decelerating below the set vehicle speed _V0 , etc.
When operating the accelerator pedal in the return direction, step 200 → step 201 → step 202 → step
The operation flow is 206 → step 203 → step 204 → step 205, and in step 205, a control current signal (i) corresponding to the searched target control current value i ^* and the control gradient selected in step 203 is output. .

In addition, when the accelerator pedal is suddenly released from the depressed state and the tuck-in occurrence condition that the vehicle speed V is equal to or higher than the set vehicle speed _V0 is satisfied, the steps 200→Step 201→Step 202→
The process proceeds to step 206 → step 207 → step 208 → step 209, and the output of the control current signal (i) based on the previous target control current value i ^* is determined according to the accelerator opening change rate |Å| and the total duration according to the vehicle speed V. Lasts for ti.

Step 206 is a judgment step in which it is determined whether the take-in occurrence conditions are satisfied, that is, the accelerator opening change rate Å is negative less than ₀ and the vehicle speed V is equal to or higher than the set vehicle speed V0.

Steps 207 to 209 are tack-in suppression control steps. In step 207, the duration ta corresponding to the absolute value |Å| of the accelerator opening change rate Å is searched from the map, and in step 208, the duration ta corresponding to the vehicle speed is searched. is searched from the map, and in step 209, the control current signal (i) based on the previous target current value i ^*
is output for the total duration ti (= ta + tv).

Although not shown, the map between the absolute value of the accelerator opening change rate |Å| and the duration ta is such that as |Å| increases, ta becomes longer. The map of and duration tv is also V
The map is such that as the size of the TV gets larger, the length of the TV becomes longer.

(c) When the accelerator pedal is held When the accelerator opening change rate Å is 0 and the accelerator pedal is held, the flow is the same as when the accelerator pedal is depressed, and the control gradient is determined by the accelerator opening change rate Å. is zero, map M is selected as the control characteristic map, and simply when the vehicle speed V increases while holding the accelerator pedal, the target control current value i ^* increases as the vehicle speed V increases, and , when the vehicle speed V decreases, the target control current value i ^* decreases as the vehicle speed V decreases.

Next, the response characteristics of the control oil pressure P (differential limiting torque T) will be described with reference to FIGS. 7 and 8.

Figure 7 shows when the accelerator pedal is depressed (Å>0)
This is a response characteristic diagram of the control oil pressure P with respect to time t, in which the rise of the control oil pressure P becomes steeper when the depression speed is high, and the rise of the control oil pressure P becomes gradual as the depression speed becomes slower. It shows the characteristic that

In this characteristic diagram, P ₁ and P ₂ are target values of the control oil pressure P at each point in time. In addition, the target control current value mentioned above
i ^* is determined in accordance with the target value of the control oil pressure P. Furthermore, the transmitted torque T is proportional to the value of the control oil pressure P. Assuming that the target value of the control oil pressure changes from P ₁ to P ₂ at the current time t ₀ , the control oil pressure P approaches the target value at a gradient according to the magnitude of the absolute value |Å| of the accelerator opening change rate Å. . In other words, the transmission torque T changes according to the accelerator opening change rate Å.
The increase/decrease response speed of the torque is made variable, and a control current signal (i) is output in order to approach the target torque.

FIG. 8 is a response characteristic diagram of the control oil pressure P when the accelerator pedal is returned (Å<0), and shows the characteristic that the descending slope of the control oil pressure P is constant regardless of the return speed.

In this characteristic diagram, P ₁ and P ₂ are target values of the control oil pressure P at each time point. Now, at time t ₀ , the accelerator pedal is suddenly released, and the target value is
Assuming that P ₁ changes to P ₂ , the current target value P ₁ of the control oil pressure is changed over a predetermined duration ti (t ₁ , t ₂ ,
t ₃ , etc.), and then controlled to approach the target value P ₂ set at time t ₀ at a constant gradient. As is clear from the figure, the duration time is set to be longer as the absolute value |Å| of the accelerator opening change rate Å is greater and as the vehicle speed V is greater.

Therefore, when making a small radius turn at low speed on a mountain road, etc., the duration ti is short, for example, t ₁ hour,
Furthermore, when making a large radius turn while driving at high speed, the duration becomes longer, for example, _t3 hours.

FIG. 9 is a diagram showing temperature correction of the control current signal (i). Clutch hydraulic oil temperature of differential limit clutch
When T ₀ decreases, the viscosity of the oil increases, so the response of the control oil pressure P to the output of the control current signal (i) becomes slower. This figure shows the characteristics of the temperature correction of the control current signal (i) that is focused on. In the diagram
i ₁ ^* and i ₂ ^* are the target control current values at each time,
Now, suppose that the target value changes from i ₁ ^* to i ₂ ^* at time t ₀ . The control current signal gradually increases from i ₁ ^* to i ₂ ^* with the control gradient selected by the accelerator opening change rate Å, but the hydraulic oil temperature T ₀
By applying temperature correction to increase the gradient as the temperature is lower, it becomes possible to prevent the delay in response of the control oil pressure P caused by the change in the viscosity of the oil described above. In addition, this temperature correction control is based on the clutch hydraulic oil temperature T ₀
This can be achieved by correcting the control gradient in step 203 of FIG. 6 based on a signal from an oil temperature sensor (not shown) that detects the temperature.

As described above, the differential limiting clutch control device of the embodiment is configured to perform control in which the increase/decrease response speed of the differential limiting torque T is varied depending on the magnitude or positive/negative of the accelerator opening change rate Å. The differential limiting torque T increases or decreases depending on the response speed depending on how much the accelerator pedal is pressed or released, and it is possible to prevent wheelspin during sudden acceleration and sudden changes in vehicle behavior and steering force.

Furthermore, when tuck-in occurs due to sudden foot release from the accelerator pedal, the differential limiting torque T at the accelerator pedal depression position is maintained for a predetermined period of time according to the vehicle speed V, and then the differential limiting torque T is reduced. It is possible to suppress the tuck-in phenomenon by utilizing the understeer characteristics associated with the limited differential between the left and right wheels.

Furthermore, since the duration of the differential limiting torque T is set in accordance with the vehicle speed V, there is a strong tendency for understeer to occur, unlike when the duration is set solely based on the accelerator release degree. Therefore, the tuck-in phenomenon can be sufficiently suppressed for an optimal duration depending on the situation in which the tack-in occurs, without deteriorating the turning performance or lacking the tack-in suppressing effect.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an example of a differential limiting clutch control device is shown, but for example, the driving force of a four-wheel drive vehicle as illustrated in Japanese Patent Application Laid-Open No. 59-276048 (Japanese Patent Application Laid-Open No. 61-157437) is The present invention can also be applied to a transfer clutch that changes the driving force distribution ratio of a transfer device that distributes power to front and rear wheels, and in this case as well, the same effects as in the case of a differential limiting clutch can be obtained.

Further, in the embodiment, an electromagnetic proportional pressure reducing valve is shown as an actuator, but an example in which an electromagnetic valve that opens and closes or the like may be used to perform hydraulic control using a control signal as a duty signal may also be used.

(Effects of the invention) As explained above, in the vehicle drive train clutch control device of the present invention, when the accelerator opening suddenly decreases, the drive train clutch means is kept in the engaged state for a predetermined period of time, and the clutch remains engaged. Because this is a means of controlling the time to increase as the vehicle speed increases,
The effect is that optimal suppression of tact-in can be expected depending on the situation in which tact-in occurs.

[Brief description of the drawings]

Fig. 1 is a conceptual diagram of a claim showing a drive system clutch control device for a vehicle according to the present invention, Fig. 2 is a sectional view showing a differential device incorporating a differential limiting means of an embodiment of the device of the present invention, and Fig. FIG. 2 is a Z-direction view, FIG. 4 is a diagram showing the hydraulic pressure generator and control device of the embodiment device,
FIG. 5 is a two-dimensional control characteristic map of control current values stored in advance in the control unit of the embodiment device, FIG. 6 is a flowchart showing the flow of the differential limiting control operation of the embodiment device, and FIG. Figure and 8th
The figure is a response characteristic diagram of the control oil pressure P (differential limiting torque T) under different accelerator operation states, and FIG. 9 is a temperature correction diagram of the control current value. 1, 2... Drive wheel, 3... Power split device, 4...
... Drive system clutch means, 5 ... Input sensor, 50
1... Accelerator opening sensor, 502... Vehicle speed sensor, 6... Control means.

Claims (1)

[Claims for Utility Model Registration] A power splitting device that distributes and transmits engine driving force to front and rear or left and right drive wheels, and a power splitting device that is installed between a drive input section and a drive output section of the power splitting device, and transmits the power by a controlled external force. A drive system clutch for a vehicle, comprising drive system clutch means for generating torque, an input sensor for detecting a vehicle condition, and a control means for outputting a control signal for increasing or decreasing transmission torque based on an input signal from the input sensor. In the control device, the input sensor includes an accelerator opening sensor and a vehicle speed sensor, and the control means is configured to maintain the drive system clutch means in an engaged state for a predetermined period of time when the accelerator opening suddenly decreases, and to control the clutch engagement duration. A drive system clutch control device for a vehicle, characterized in that the clutch is controlled to be longer at higher vehicle speeds.