JPS612926A - Method of controlling oil pressure for actuator for engaging and disengaging clutch - Google Patents

Abstract

PURPOSE:To prevent a shock, by keeping the oil pressure for an actuator equal to the final oil pressure of a first pressure increase stage for a prescribed time between the first pressure increase stage in which a clutch is engaged and a second pressure increase stage in which the oil pressure is sharply increased to the maximum. CONSTITUTION:When a fork-lift truck is to be started, the duty factor for a modulating solenoid is reduced to D3% and kept at that value until a time point t1 and is thereafter increased to D1% and then decreased at a constant rate until a time point t2. After reaching D2% at the time point t2, the duty factor is kept at that value for a prescribed time and then reduced to 0% at a time point t3. Along with the changes in the duty factor, the oil pressure for an actuator for a forward movement clutch is relatively rapidly increased to a level P1 and then increased at a constant rate to a level P2. After being kept at the level P2 for a prescribed time, the oil pressure is rapidly increased to a level P3.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a power transmission system for a vehicle, and particularly relates to a method for controlling oil pressure of a clutch engagement/disconnection actuator.

BACKGROUND OF THE INVENTION Power transmission systems for vehicles in which gear shifting is performed automatically are already known. Conventionally, the transmission was connected to the 7"C engine via a torque converter, but with this type of power transmission system, there is a scope for improving transmission efficiency and acceleration. In recent years, a type of power transmission device (hereinafter referred to as a direct power I-lane) that connects the transmission directly to the engine via a clutch without going through a lux converter has come into use.

However, with a torque converter, even if there is a certain degree of discrepancy in the rotational speed or torque between the engine and transmission sides, the mismatch is absorbed by the gentle action of the torque converter, resulting in a smooth start. However, since the direct power train does not use such a buffer 11, various problems occur.

One of them is '! II When the loaded load is large or when the running resistance is large, such as on an uphill slope, when the clutch is changed from the disengaged state to the engaged state, the heavy vehicle continues to accelerate and fires twice. There's a problem. Conventionally, in a vehicle power transmission system equipped with a torque converter, a solenoid duty-controlled modulator is used. A type of bending control valve has been used to control actuator oil pressure by controlling the amount of hydraulic oil drained from an oil passage that supplies oil pressure to a clutch engagement/disconnection actuator to a train passage.

7. When the clutch is turned from the disengaged state to the engaged state, the modulus-tiing ratio 1/noid is linearly changed over time as shown in FIG.
By doing so, as shown in Fig. 8, the L-actuator oil pressure is adjusted to the /IIIrT required for the clutch in the 1-person position and -J-B.
:The stomach slowly rises at 1,000 yen, then rapidly at the highest /It+ If' FF, and after the 1st pressurization stage, the pressure rises to 7N. Sif
Sa-(! It was done. However, the same action as Gowa...
: When I applied the control of the hydraulic pressure to the Gileno Ztope Train, I found that the load on the vehicle was small.
] When the road surface is level, the vehicle accelerates, yaws, and yaws are 1
Since the vehicle starts in a normal state that only appears once, if the load is large or if the vehicle starts on an uphill slope, the signal will be transmitted through the vehicle. It was found that the torque changes as shown in Figure 9, and a two-stage shock appears, resulting in poor riding comfort.

Problems to be Solved by the Invention: As mentioned above, the present invention solves the problem of 2.
This was done in order to solve the problem of stage shock, which makes the vehicle uncomfortable to ride.

Means for Solving the Problems 7. In order to solve the problems in item 1-, the present invention provides a solenoid device 1- in the die I node power I lane.
In controlling the hydraulic pressure of the clutch engagement/disconnection actuator by a tee-controlled modulator, a hydraulic pressure holding stage is performed in which the hydraulic pressure of the actuator is maintained at the final hydraulic pressure of the first pressure increasing stage for a certain period of time between the first pressure increasing stage and the second pressure increasing stage. It is characterized by the fact that it has been established.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

An example of a direct power train for a forklift truck is shown in FIG. 4, where 10 is an engine. A pump 12 and a planetary gear unit 14 are connected to the engine 10, and the planetary gear unit 14 includes sun gears 16, 18, 20, 22, . Planetary gears 24, 26, 28, 30. ring gear 32,
34, 36° 38, forward clutch 40. Clutch for reverse 42° Rip edge for first 44. For use with the river crane F46, third crane 7,48, etc. In a loose clutch, the clutch element on the negative side is not rotatable.When the forward clutch 40 is in the engaged state, either the first, second, or third clutch is in the engaged state. 3 forward gears or 3 reverse gears is shifted according to each time.In other words, the planetary gear 1-knit 14 of this embodiment is used as a clutch that transmits or cuts off the rotation of the engine 10 and a transmission that controls gear shifting. If separated, the forward clutch 40 and the reverse clutch 42 constitute a clutch, and the remaining portion constitutes a transmission.

The above planetary gear unit, G14 has a binion of 50.5
2 and gears 54 and 56 is connected thereto, and left and right drive wheels 62 are connected to the reducer 58 via a differential gear device 60. Further, the engine 10
The rotational speed of the vehicle is detected by a rotation sensor 64, and the vehicle speed is detected by a rotation sensor 1166. In addition, although Figure A is omitted, the accelerator opening degree, load load 1 inching pedal stroke, vehicle body tilt angle, whether the soft lever is in the neutral position, brake pedal 1
The presence or absence of Eisaku is detected by each sensor, and based on the detection results, the clutch 40° 42.44.
By selectively IMing either 46 or 48, the forklift 1-truck is automatically started and shifted.

A hydraulic circuit for this purpose is shown in FIG. The engine 10
A pump 12 connected to the pump 12 sucks hydraulic oil from the tank 70 and pumps the clutches 40, 42, 44, 46 and 48.
actuator 40a.

42a, 44a, 46a and 48a.

The hydraulic pressure supplied to these is always kept at a constant value by the regulator 72, but the forward clutch 40 and the 7 clutches 40a and 4 of the multi-advance clutch 42
The oil pressure supplied to 2a is further controlled by a modulator 74 by cF.

As shown in FIG. 6, the modulator 74 has a drain passage 78 that drains hydraulic oil from a main passage 76 connecting the regulator 72 and the actuator 40a or 42a to the tank 70. A relief valve 80 is provided at the connection to the relief valve 76.The relief valve 80 is equipped with a valve element 82, a spring 84, a piston 86, a spring 88, etc. 8
It changes as the position of fi changes.

The position of the piston 86 is determined based on the urging force of the springs 88 and 84 and the oil pressure in the hydraulic chamber 90.
The hydraulic pressure in the hydraulic chamber 90 is controlled by the electromagnetic on-off valve 92.

Hydraulic oil in the main passage 76 is guided into the hydraulic chamber 90 via a control passage 9G having a throttle 94, and this oil
The oil pressure in the hydraulic chamber 90 is controlled by controlling the amount of hydraulic oil in the chamber 90 flowing out from the electromagnetic on-off valve 92. The electromagnetic on-off valve 92 closes when the modulating solenoid 98 is off, that is, when no current is supplied, and opens when the modulating solenoid 98 is on. The amount of hydraulic oil flowing out from the hydraulic chamber 90 is controlled by changing the duty ratio of the current.

The hydraulic oil whose hydraulic pressure is controlled by the modulator 74 is transferred to the forward clutch 40 by a manual directional control valve 100.
The actuator 40a and the actuator 42a of the reverse clutch 42 are selectively supplied. That is, the directional control valve 100 is connected to a shift lever (not shown), and when the shift lever is in the neutral position, hydraulic oil is not supplied to either of the actuators 40a, 42a, and the shift lever is operated to the forward or reverse position. When the actuator is activated, hydraulic oil is supplied to the corresponding actuator.

On the other hand, for the regulator 72 and the first.

Second and third clutch actuator 4
Directional switching valves 102 and 104 are disposed in the middle of the oil passage connecting the oil passages 4a, 46a, and 48a.

When the drain passages 110 and 112 are opened by energizing the shift solenoids 106 and 108, respectively, the directional control valves 102 and 104 are in the fifth position.
The state shown in the figure is reached, and the shift solenoids 106 and 1
08 can be switched to the opposite state when each is demagnetized. That is, Solenoid 1106.1
Actuator 4 depending on the on/off state of 08.
4a, 46a, and 48a, and thereby the first clutch 44. The second clutch 46 or the third clutch 48 is connected.

The on/off states of the shift solenoids 106 and 108 and the modulating solenoid 98 are controlled by a microcomputer based on a control program and signals from each of the sensors, and this microcomputer is well known. Further, since it is not essential for understanding the present invention, illustrations and detailed explanations will be omitted.

In the following click-lit trunk equipped with a power I-lane configured in a L-shaped configuration, the shift lever that was in the neutral position is operated to the forward direction, and the accelerator pedal is depressed to start the forklift truck. In this case, the duty ratio of the modulating solenoid 98 is varied over time as shown in FIG. That is, while the forklift truck is moving forward, the duty ratio of the modulating solenoid 98 is maintained at 100%, but at time t0 the duty ratio decreases to D3%.
It is held at that value until time t, then it is increased to 01%, and thereafter it is decreased at a constant rate until time 2.
1, and after reaching 7% of the duty ratio at time t2, the duty ratio decreases to 0% at time t3 for a certain period of time. The oil pressure of the actuator 40a changes as shown in Fig. 2. Although there is a slight delay from time t0,
The oil pressure increases to Pl relatively quickly, and then increases to P2 at a certain rate and is maintained at that value for a certain period of time.
Maximum oil pressure P3 which is the setting tune V1 of the regulator 72
It was quickly raised to the highest level.

The pressure increase stage from P to P2 is the first pressure increase stage, the stage where P2 is maintained is the oil pressure holding stage, and the pressure increase stage from P2 to P3 is the second pressure increase stage. If the load of the forklift truck is small and the road surface is level,
During the first pressure increase stage, the forward clutch 40 is clearly engaged and substantially slip-free, allowing the forklift truck to start smoothly. That is, the second
Although the oil pressure rising curve shown in the figure is ideal,
As shown by the two-dot chain line A in Fig. 1, if the duty ratio is decreased at the same rate from time t0 to t1 as from time t□ to t2, a large delay will occur in the hydraulic pressure. , thus an ideal oil pressure rise curve cannot be obtained. On the other hand, as shown in FIG.
, the duty ratio is set to −1, the duty ratio D is an equivalent percentage compared to the target value (the value represented by the two-dot chain line A).
After setting the duty ratio D to 3%7 and holding the duty ratio D3% for a certain period of time, it almost reaches the target value and setting it again to %7, the ideal oil pressure fluctuation curve shown in Fig. 2 is obtained, and the forward movement The clutch 40 can smoothly transition from the disengaged state to the engaged state in a short period of time.

In this way, if the running resistance of the forklift I/rack is small, the forward clutch 40 will be fully engaged when the hydraulic pressure of the actuator 40a is raised to P2, so the ib pressure will immediately rise to P3 from this state. There is no problem in raising it, but if the load of the forklift truck is large or the road surface has an uphill slope. If the running resistance is large, immediately after the oil pressure reaches P2, the forward flannel is still running.
Since there is a considerable amount of slippage in the forklift truck, if the oil pressure is suddenly increased to P3 in that state, the forward clutch 40 will be depressed rapidly, and at this point the forklift truck will An acceleration shock occurs, and a shock of 21111 is generated together with the acceleration shock that occurs in the process of increasing the oil pressure from P□ to P2, resulting in poor riding comfort.

On the other hand, as in this embodiment, from time t2 to t3
If the duty ratio is maintained at a constant value of 1 to 2% (I) and the actuator oil IF is held at the final oil field P2 of the first pressure increase stage for a certain period of time, the forward clutch 40 The forklift truck is operated for a certain period of time with a certain amount of lPt being generated in the engine 10. Therefore, the torque transmitted from the engine 10 to the planetary gear unit L I 4 is as shown in FIG. It reaches its maximum at the end of the boost stage, and the acceleration of the forklift trunk also reaches its maximum, but after that, as the forklift truck transitions to a steady running state, both the acceleration and torque decrease, causing the acceleration r/yonoku to change twice. Successive occurrences of 1: are avoided.

In addition, if the first pressure increase stage is extended and the actuator oil pressure continues to be increased by ten folds without providing the oil pressure holding stage, the torque will continue to increase, and an overload 6i1 will be added to the engine lO, causing the engine to stop. However, in this example, oil JE I! Once the engine reaches the holding stage, the torque will no longer increase, so there is no engine stop BH, and there is no need to use a high horsepower engine to prevent engine stop.

In the following -1-, we have explained the case where the forklift truck is started or kicked in the forward direction, but of course when it is started or started in the reverse direction, it is also in the disconnected state for shifting and then in the engaged state. In this case, the actuator oil pressure can be similarly controlled.

Further, in this embodiment, the duty ratio is a constant value I
], the time maintained at % is the same whether the running resistance of the forklift truck is small or large. Based on this, the length of the oil pressure holding stage can be adjusted depending on the magnitude of the running resistance by increasing the time to hold the duty lL constant when the running resistance is large and shortening it when the running resistance is small. It is also possible to change.

In addition, the transmission is not a constant mesh type but a selective sliding type, and the clutches and clutches are also ordinary friction clutches that are commonly used in combination with the transmission, and their operation is automated. It is also possible to apply the present invention to train control.

Although not illustrated individually, it goes without saying that the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

Effects of the Invention As explained in detail above, the present invention provides an oil pressure holding stage between the first pressure increase stage and the second pressure increase stage, so that the clutch is not disengaged when the vehicle running resistance is large. When changing from the state to the engaged state, there is a certain degree of disengagement in the clutch even at the end of the first pressure increase stage, but the vehicle is accelerated while the oil pressure holding stage continues for a certain period of time. As a result, the load on the transmission side is reduced, and clutch slippage becomes virtually negligible. therefore,
Part 1: Even if the actuator oil pressure is rapidly increased in the first pressure increase stage, no change occurs in the power transmission state, and no acceleration shock occurs in the vehicle. In other words, even if the running resistance is large, only one acceleration shock is generated in the vehicle, and the deterioration of riding comfort caused by the two-stage shock can be avoided.

Note that if the running resistance of the vehicle is small, the clutch will be in the engaged state at the end of the first pressure increase stage to the extent that slippage can be ignored, so that the clutch will remain in a state with virtually no slippage during the oil pressure holding stage. is maintained, and there is no substantial difference from the case of immediately transitioning from the first boosting stage to the second boosting stage.

In addition, if the first pressure increase stage is extended instead of providing the oil pressure holding stage and the active 4 ether pressure I■ is raised as before, there is a risk that the engine load will become excessive and the engine will stop. In order to avoid this, it is necessary to install an engine with a large horsepower, but by providing a hydraulic pressure holding stage, such inconvenience can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of duty adjustment control of the modulating solenoid F in an embodiment of the present invention, and FIG. The J graph in FIG. 3 is a graph showing changes in torque transmitted from the engine via the clutch. FIG. 4 is a conceptual diagram showing an example of a direct bamanote lane to which the method of the present invention can be applied. FIG. 5 is a circuit diagram showing a hydraulic circuit for operating the actuator of each clutch in FIG. 4. Figure 6 is the 5th
It is an explanatory view showing a modulator shown in the figure. FIGS. 7, 8, and 9 are diagrams corresponding to FIGS. 1, 2, and 3, respectively, when conventional tutee ratio control is applied to the direct bar "no" lane. 12: Pump 14; Planetary Caco, Nino I/4
0: Forward clutch 40a, 42a near actuator 42: (Multi-advance clutch, 172; Regulator 74; Modulator 76: Main passage 7) i: Train passage 80: Relief hub 82: /l'γ
84.88 spring 8 (i: piston
90. Oil room 92: ? h Magnetic on-off valve 94
: Throttle 96; Control passage 98; Mosh rating solenoid +00.102.104: Directional switching valve 1 (1G, 108: Nft solenoid output Yutaka Co., Ltd. [[1 Automatic Loom Manufacturing Co., Ltd. Fujitsu Co., Ltd.] No. 1 Figure --- La Moema JP 6l-2926 (7) Figure 7 - Moema Figure 9, 1 -→ Time

Claims (1)

[Claims] A solenoid duty-controlled modulator is used to control the hydraulic pressure of a clutch connection/disconnection actuator in a vehicle power transmission system in which an engine and an automatic transmission are directly connected by a clutch without going through a torque converter. A first pressure increasing stage in which the hydraulic pressure of the actuator is gradually increased by linearly changing the duty ratio of a modulating solenoid over time to bring a clutch that is in a disengaged state into an engaged state. and then a second pressure increase stage in which the oil pressure is rapidly increased to the maximum pressure, the hydraulic pressure of the actuator is maintained at the final pressure of the first pressure increase stage for a certain period of time between the first pressure increase stage and the second pressure increase stage. A hydraulic control method for a clutch engagement/disconnection actuator, characterized by providing a hydraulic pressure holding stage.