JPS5917295B2 - Transmission automatic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic transmission control device, and particularly to a transmission automatic control device having an overdrive function.

In electronic automatic transmissions, control signals are detected based on various driving conditions of the vehicle, and the signals are used to control hydraulic control valves to switch and control the transmission according to vehicle speed, throttle opening, etc.

Further, in such an automatic transmission, as the vehicle speed increases, the transmission is controlled to switch from the top gear position (for example, third gear position) to overdrive, thereby achieving an efficient driving state.

The above-mentioned automatic transmission having an overdrive function performs a driving operation in which the overdrive state is continuously maintained while the accelerator is opened all the time under certain driving conditions.

An example of such a driving condition is when entering a long uphill road while the overdrive function is activated. There may be cases where the vehicle is driven with the opening position unchanged.

Driving the vehicle with a large accelerator opening as described above has a major disadvantage in that engine negative pressure cannot be utilized.

In other words, engine negative pressure is widely used in the vehicle control system as its operating force, and since the engine negative pressure cannot be used effectively at the large accelerator opening described above, the control system's operation is inhibited, which is an important problem. It was causing a problem.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an improved automatic control device that can cancel the overdrive function when engine negative pressure falls below a predetermined value. It is in.

In order to achieve the above object, the present invention is characterized in that a hydraulic control valve that performs overdrive switching control is controlled by a cancel switch device, and further, the cancel switch device is controlled and operated by an engine negative pressure detector.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an automatic control system according to the present invention, in which an overdrive transmission includes a hydraulic control valve 10 whose conduit 12 is connected to the transmission hydraulic circuit for effecting overdrive switching.

The hydraulic control valve 10 includes a suspension solenoid 14 and a plunger 16, and the plunger 16 is constantly urged downward in FIG. 1 by a spring 18.

The tip of the plunger 16 engages with the drain port 12a of the conduit 12, and the overdrive function is disabled when the plunger 16 closes the drain port 12a.

Then, when the excitation current is supplied to the control solenoid 14 and the plunger 16 moves upward in FIG.
2a opens and the transmission overdrive function becomes effective.

In the present invention, the excitation current to the control solenoid 14 of the hydraulic control pulp 10 is controlled by a cancel switch device 20 consisting of a cancel relay.

Cancellation relay 20 includes a relay coil 22 and relay contacts 24 and 26, one end of solenoid 14 is grounded, and the other end is connected to ignition switch 28 via relay contact 26.

The other end of the ignition switch 28 is connected to a battery 32 via a fuse 30.

On/off control of the cancel relay 20 is performed by a negative pressure detector 34
This is done by

The negative pressure detector 34 includes an upper limit negative pressure switch 36 and a lower limit negative pressure switch 38, giving the negative pressure detector 34 a hysteresis characteristic.

One end of the upper limit negative pressure switch 36 is connected to the relay coil 22, and the other end is grounded.

On the other hand, the lower limit negative pressure switch 38 has one end connected to the relay contact 24 and the other end grounded, forming a self-hold circuit for the cancel relay 20.

Both switches 36, 38 have different operating ranges relative to engine negative pressure, and FIG. 2 shows their respective characteristics.

The characteristics in Figure 2 are as follows: switch 3 for engine negative pressure on the horizontal axis
The on/off operation of switch 6 is at characteristic 36A, and switch 38
The on-off characteristics of 38A are shown.

As is clear from FIG. 2, the switch 38 is turned off at negative pressure P1 and turned on at P2.

Similarly, the switch 36 is turned off at negative pressure P3 and turned on at P4.

The automatic control device according to the present invention has the above configuration, and its operation will be explained next.

When the engine negative pressure is at a value sufficient to operate the control system (set to negative pressure 24 or higher in Figure 2), both switches 36 and 38 of the negative pressure detector 34 are in the on state, canceling the Relay coil 22 of relay 20 is energized and its contacts 24,26 are also in the on state.

Therefore, the control solenoid 14 of the hydraulic control valve 10 is supplied with an exciting current, and the plunger 16 is connected to the drain port 12.
a is opened, and the transmission has the overdrive function enabled.

Therefore, when the vehicle speed increases and the desired conditions are met, the transmission is switched to overdrive.

Next, when the engine negative pressure decreases to P3 in FIG. 2, the switch 36 turns off, but the cancel relay 20
4 and the switch 38, the overdrive switching control of the pulp 10 is operating effectively.

Therefore, in this state, the overdrive state is still maintained, or overdrive switching is automatically performed as the vehicle speed increases.

When the engine negative pressure further decreases and reaches Pl, switch 3
8 is turned off, and as a result, the self-hold circuit of the cancel relay 20 is released, and the relay contacts 24 and 26 are turned off.

In this state, the excitation current to the control solenoid 14 is cut off, and the hydraulic control valve 10 closes the drain port 12a of the conduit 12.

Therefore, the overdrive function of the transmission is disabled, and if an overdrive action is being performed at this time, the transmission is automatically switched to the top gear position, and transmissions in other gear positions are placed in overdrive. It will not be switched to.

As described above, when the engine negative pressure falls below the predetermined value (Pl in Figure 2), the overdrive function can be reliably disabled, and the engine negative pressure can be returned to the predetermined value or higher again. becomes possible.

When the negative pressure returns, the switch 38 is turned on at P2, but the relay 20 is not energized because the contact 24 is off, and the relay 20 is not turned on until the switch 36 is turned on when the engine negative pressure reaches P4. can be returned to the on state.

The two switches 36 and 38 of the negative pressure detector 34 are effective in preventing bunching of the cancel relay 20 due to changes in engine negative pressure.

The switches 36 and 381 forming the negative pressure detector 24 can be installed in the intake manifold or vacuum hose of the engine;
Although several switches 36 and 31 are used, it is also possible to use a single pressure switch as long as it has hysteresis characteristics.

As explained above, according to the present invention, even in a transmission having an automatic overdrive switching function,
This has the advantage that when the engine negative pressure falls below a predetermined value, the overdrive function is disabled and the engine negative pressure used in the control system can be reliably obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing a preferred embodiment of the automatic control device according to the present invention, and FIG. 2 is a characteristic diagram of the negative pressure detector in FIG. 1. 10... Hydraulic control valve, 14... Control solenoid, 20... Cancellation switch device, 34... Negative pressure detector.

Claims (1)

[Claims] 1. In an automatic transmission control device including a hydraulic control valve that performs overdrive switching control based on a signal detected based on vehicle running conditions, a cancel switch device that controls the supply of excitation current to a control solenoid of the hydraulic control valve; Automatic transmission control that includes a negative pressure detector that detects engine negative pressure and activates a cancel switch device, and that cancels the hydraulic control valve and stops the overdrive function when engine negative pressure falls below a predetermined value. Device.