JPS6354936B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a creep prevention device for a vehicle equipped with an automatic transmission.

When a vehicle equipped with an automatic transmission is stopped with its shift lever in position D (forward position),
A phenomenon called creep occurs in which the vehicle tends to move forward against the driver's will due to the stirring torque generated in the fluid torque converter.

Because of this creep, the driver has to keep pressing the brake pedal to a certain degree while the vehicle is stopped, and the engine also has to open the throttle an extra amount to compensate for the stirring torque. , the fuel consumption rate becomes high, which is not preferable from the viewpoint of energy saving.

As one method to prevent this creep, for example, Japanese Patent Publication No. 49-5772 proposes to remove the hydraulic pressure supplied to the starting clutch only when the clutch is stopped; this method achieves the intended purpose. It can be achieved.

However, the following problems still remain to be solved when this method is put into practical use.

That is, the first problem is that if the hydraulic pressure in the starting clutch is removed while the vehicle is stopped, the starting response will deteriorate due to air bubbles that are generated in the oil passage between the control valve and the starting clutch and in the piston chamber. This results in an unpleasant shock when starting suddenly.

In order to solve this problem, it is effective to maintain a weak pressure in the starting clutch even during creep prevention to prevent bubbles from forming.

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a creep prevention device for a vehicle that has a simple structure and can accurately control and prepress the internal pressure of a starting clutch while the vehicle is stopped.

The second problem is that when starting, a smooth start cannot be obtained unless the hydraulic pressure supplied to the starting clutch is gradually increased.
It is a type of valve that switches between ON and OFF, so you have to accept a certain amount of shock when starting.

Although it is obvious that such a problem can be solved by adding a gradual increase valve that slowly increases the pressure, adding a new gradual increase valve of this type increases the overall size and weight of the device. In addition, a new problem of complication arises.

Therefore, a second object of the present invention is to provide a creep prevention device for a vehicle having a simple structure in which the switching control valve itself has a pressure gradual increase function.

A third problem is that when this switching valve is driven by a solenoid, in order to overcome the expected sliding resistance of the switching valve and ensure good operation, the solenoid must be driven to a certain degree. It is necessary to apply force by design, and for this reason the solenoid is large and
It becomes heavy and expensive, and its power consumption also increases, resulting in an increase in self-heat generation. This issue of heat generation is particularly problematic in recent years, when urban traffic congestion is severe and creep prevention devices are used frequently and for relatively long periods of time. This results in a vicious cycle in which the solenoid needs to be made even larger.

Therefore, the third objective of the present invention is to
Another object of the present invention is to provide a novel creep prevention device for a vehicle that operates stably with a small-capacity solenoid.

In order to achieve the above objects, the present invention provides a creep prevention device that includes a frictional engagement element that intervenes in the transmission system of a transmission to establish a gear ratio for starting, and a hydraulic chamber of the frictional engagement element that is connected to an oil tank. a spool-type switching valve that opens and closes the oil passage connected to the oil passage; a spring body that holds the switching valve in a first operating position; and a spring body that holds the switching valve in a first operating position; The valve comprises a poppet-type solenoid valve that is held in a second operating position to create a pressure difference on both end faces of the spool of the switching valve, and an electric circuit that detects the idling state of the engine and operates the solenoid valve. .

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a power train of an automatic transmission suitable for applying the present invention, and FIG. 2 is a control circuit diagram of the device of the present invention.

In FIG. 1, the output of the engine E is transmitted to a pump impeller 12 of a torque converter 10, and is further hydrodynamically transmitted to a turbine impeller 14.
When the torque is amplified here, the stator 16 bears the reaction force. Although the right end 13 of the pump impeller 12 is not shown, the hydraulic pump 50 shown in FIG.
to drive.

The turbine impeller 14 is integrally connected to a main shaft 20 of an auxiliary transmission 18, and on this main shaft 20, from the left in the figure, a third speed (top) drive gear 22 and a second speed (second) clutch are mounted. C ₂ and a first speed (low) clutch C ₁ are each tied together. Furthermore, this main shaft 2
0, as shown in the figure, there is a second shaft which rotates together with the shaft 20 when the clutches C ₂ and C ₁ are engaged.
A speed drive gear 24 and a first speed drive gear 26 are loosely fitted to the shaft 20 so as to be relatively rotatable.

On the other hand, a countershaft 30 is provided parallel to the main shaft 20, and the countershaft 30 has a final drive gear 32, a third
The speed clutch C ₃ , the second speed driven gear 34, and the first speed driven gear 36 are each connected integrally.

The first speed driven gear 36 and the countershaft 3
0, a one-way clutch _C4 that allows torque transmission only from the main shaft 20 to the countershaft 30 side may be incorporated as shown.

Also, on the countershaft 30 is a third speed clutch.
A third speed driven gear 38, which rotates together with the shaft 30 when _C3 is engaged, is loosely fitted.

The torque of the final drive gear 32 is transmitted to the final driven gear 40, which drives the left and right front wheels _WL and _WR through a differential gear 42 assembled integrally with the final driven gear 40.

In order to simplify the explanation, a reverse power train and a parking device are omitted in FIG. 1.

In FIG. 2, the hydraulic control mechanism 44 outputs a vehicle speed signal 4.
6. Selectively supply the discharge pressure of the hydraulic pump 50 to the clutch C ₁ , C ₂ or C ₃ according to the throttle opening signal 48 to switch the power train shown in FIG. This is to establish the speed ratio of the second or third speed. Furthermore, this hydraulic control mechanism 44
There may be fully hydraulic types, or there may be electro-hydraulic types using solenoid valves, etc., but the detailed structure is arbitrary. Further, this hydraulic control mechanism 44 may make the discharge pressure of the hydraulic pump 50 itself variable in response to the torque conversion ratio signal 52 of the torque converter 10.

On the other hand, an orifice 55 is provided in the oil passage 54 between the clutch C ₁ and the hydraulic control mechanism 44.
An oil passage 56 branches from the middle of the oil passage 56, and a spool valve 60 that is opened and closed by a pilot type solenoid valve (electromagnetic valve) 99 is provided between the oil passage 56 and the oil tank 58.
is interposed. These solenoid valve 99 and spool valve 60 correspond to non-creep means.
This spool valve 60 guides the pressure of the oil passage 56 to the upper and lower end surfaces of the spool valve 60 through orifices 62 and 63, respectively, and the spool valve 60 is normally positioned at the lower limit due to the elastic force of the spring 64. , oil road 56
The communication with the oil tank 58 is cut off.

An orifice 6 is located in the center of the upper part of the spring 64.
Valve seat member 6 provided with an orifice 66 having a larger diameter than 2
8 is incorporated, and the lower part of the valve seat member 68 constitutes a spring chamber 65 finished to have the same diameter as the spool valve 60.

The orifice 66 of the valve seat member 68 is connected to the second spring 7
As shown, it is closed by a movable iron core 72 that is urged downward at zero, and is opened only when a solenoid 74 is energized. When the movable iron core 72 is lifted upward, the spring chamber 65 communicates with the oil tank 58 via an orifice 66, an oil passage 69 provided in the valve seat member 68, and an oblique oil passage 76. Connect the oil passage 56 to the oil tank 5
The port 78 communicating with the spool valve 8 has a circular cross-sectional shape, and is configured such that its effective opening area gradually increases as the spool valve 60 moves upward.

On the other hand, the electric circuit 80 operates the solenoid 74, and the vehicle speed sensor 85 is composed of a reed switch 86 and a magnet 87 installed on the speedometer cable, and the reed switch 86 detects the rotation of the cable. .

A vehicle speed detection circuit 81 converts the output of the vehicle speed sensor 85 into a low level and a high level depending on the set vehicle speed (set speed of the speedometer cable) and sends the output to an AND circuit 82 .

Reference numeral 88 in the figure is an engine idling detection switch, which sends high-level and low-level outputs to the AND circuit 82 when the accelerator pedal 89 is not depressed and when it is depressed, respectively. AND circuit 8
The output of transistor 2 is connected to the base of power transistor 84 via resistor 83, its emitter is grounded, and its collector is connected to solenoid 74. Although the other end of the solenoid 74 is not shown, it is assumed that it is connected to the positive terminal of the battery via an ignition switch.

Next, the operation of the device of the present invention will be explained.

Assuming that the car is currently stopped in an idling state and the shift lever is shifted to the D position (forward position) in the driver's seat, the hydraulic control mechanism 44 controls the discharge pressure of the hydraulic pump 50.
Control to send to C ₁ .

However, in this state, the electric circuit 80 is also connected to the vehicle speed detection circuit 81 and the idling detection switch 88.
are both emitting high-level signals, so the solenoid 74 is energized and the movable core 72 is lifted, so there is almost no pressure in the spring chamber 65, and the spool 61 is therefore The port 78 is opened by being pushed up by the hydraulic pressure of the lower end surface.

As described above, the opening area of the port 78 gradually increases as the spool 61 moves upward, so the hydraulic pressure acting on the lower end surface of the spool 61, in other words, the pressure of the clutch _C1 is determined by the strength of the spring 64. The upward movement of the spool 61 stops when the pressure is maintained at the set pressure. At this time, the movement of the spool 61 is the orifice 6.
3, the pressure in the clutch _C1 is controlled to be very stable. At this time, the set value of the oil pressure in the clutch C ₁ is selected to be approximately equal to the set load of the spring that pushes back the piston in the clutch C ₁ , or slightly smaller than this, and the clutch C ₁ has an engagement force The creep phenomenon is prevented because it is placed in a state where there is almost no

However, since the oil passages inside the clutch _C1 and extending therefrom are all pressurized to a weak pressure, no air bubbles are generated, and the vehicle is ready for the next start.

When the accelerator pedal 89 is depressed in such a state, the output signal of the idling detection switch 88 becomes low level, the solenoid 74 is demagnetized, and the orifice 66 is closed, so that the same pressure is applied to the upper and lower end surfaces of the spool 61. It will work,
Pushed by the spring 64, the spool 61 gradually moves downward, and the port 78 is gradually narrowed.
4, that is, the pressure in clutch _C1 , is gradually increased to ensure a smooth start. in this case,
It is the dimensions of the two orifices 62, 63 that determine the degree of pressure increase.

If the vehicle speed exceeds the set value, the output of the vehicle speed detection circuit 81 becomes a low level, and the accelerator pedal 8
Solenoid 74 is demagnetized regardless of the position of 9.

In the above embodiment, the vehicle speed signal 46 and the throttle opening signal 48 are input to the AND circuit 82. However, as previously proposed by the applicant, the brake signal or the water temperature signal is input to the signal 9.
0 may be input, and the creep prevention device may be configured to operate only when the brake pedal is depressed or when the engine water temperature is equal to or higher than a set value.

In addition, as shown in Figure 1, if one-way clutch _C4 is installed in the transmission path that establishes the speed ratio in first gear, the engine brake in first gear will not work, so at this time the vehicle speed signal will not be activated. AND circuit 8
There is no positive reason to enter 2.

Furthermore, the throttle opening signal 48 can be replaced by another physical quantity representative of the engine output, such as the negative pressure of the intake manifold.

Furthermore, in the above embodiment, the switching valve 60 guides the pressure inside the clutch C ₁ to both end faces of the spool 61 via the orifices 62 and 63, and eliminates the pressure acting on the upper end face of the clutch C1 by operating the solenoid 74. However, the same effect can be obtained by alternatively maintaining the upper end face at tank pressure (atmospheric pressure) at all times and eliminating the pressure acting on the lower end face by operating a solenoid.

In the above, the driving force of the solenoid 74 only has to overcome the force remaining after subtracting the hydraulic pressure acting through the orifice 66 from the pressing force of the second spring 70, and since the opening area of the orifice 66 itself is extremely small, The solenoid 74 can be designed to be small, lightweight, and low power.

In addition, the movable iron core 72 of the spool 61 is connected to the orifice 6.
Since the port 78 starts to be throttled as soon as the clutch C 6 is closed, the problem of starting response is solved, and the movement of the spool 61 is gradual due to the throttle effect of the orifices 62 and 63, reducing the pressure inside the clutch C ₁ . A pressure gradually increasing function can be provided to gradually increase the pressure, thereby realizing a smooth start.

Furthermore, during creep prevention when the solenoid 74 is energized, the spool ₆₁ operates as a kind of pressure control valve. As a result, delay in operation is effectively prevented.

Furthermore, the creep prevention control valve according to the present invention can be made smaller, and the device itself can be made smaller and lighter.

According to the present invention, the above effects can be achieved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic diagram of a power train of an automatic transmission suitable for applying the present invention, and FIG. 2 is a control circuit diagram of the device of the present invention. In the drawing, 10 is a torque converter, 44 is a hydraulic control mechanism, 50 is a hydraulic pump, 55, 62, 6
3 and 66 are orifices, 58 is an oil tank, 60 is a spool valve, 61 is a spool, 64 and 70 are springs, 72 is a movable core, 74 is a solenoid, 78 is a port, 80 is an electric circuit, 81 is a vehicle speed detection circuit,
82 is an AND circuit, 85 is a vehicle speed sensor, 88 is an idling detection switch, 89 is an accelerator pedal, C ₁ , C ₂ , C ₃ and C ₄ are clutches, and E is an engine.

Claims (1)

[Scope of Claims] 1. A hydraulic frictional engagement element that is engaged and disengaged by being supplied with pressure oil to the transmission system of the engine power input through the torque converter is provided, and the engagement of the frictional engagement element is - A transmission that establishes the gear ratio of the transmission system upon disengagement; and a non-creep mechanism that reduces the pressure of the pressure oil supplied to the frictional engagement element to below the engagement pressure of the frictional engagement element under a predetermined operating condition of the vehicle. In the creep prevention device for a vehicle, the non-creep means is configured such that pressure oil supplied to the frictional engagement element is introduced into a pressure chamber, and the frictional engagement element is introduced into the pressure chamber with an opening degree corresponding to the pressure within the pressure chamber. Creep prevention for a vehicle, comprising: a throttle valve that opens an engagement element to an oil tank; and a solenoid valve that opens a pressure chamber of the throttle valve to the oil tank in response to a current applied to a solenoid. Device. 2. The vehicle creep prevention device according to claim 1, characterized in that a throttle is interposed in an oil passage connecting the pressure chamber of the throttle valve to an oil tank in series with the electromagnetic valve.