JP2564931B2 - Idle up device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an engine for a forklift truck or the like, which automatically operates even when a high load is applied by operating a cargo handling lever or the like when the engine speed is low. The present invention relates to an idle up device capable of opening a throttle valve.

[Prior art]

When the engine speed is low (when idling),
An idle up device is known as a device for controlling the idling state stably by opening the throttle valve when the engine load increases.

Such idle-up devices include those shown in FIGS. 5 to 8. That is, as shown in FIG. 5, the idle-up device includes an intake manifold 8 connected to a combustion chamber of an engine (not shown), a throttle valve 82 provided in the intake manifold 8, and an opening of the throttle valve 82. An actuator 9 for controlling the degree via a lever 83, and a negative pressure pipe 89 for introducing a negative pressure provided between the actuator 9 and the throttle valve downstream side 85.

The intake manifold 8 is a throttle valve.
A carburetor 81 (not shown) is provided on the upstream side 80 of the 82. Further, the lever 83 has an adjusting screw 84 on the upper portion.

On the other hand, the actuator 9 includes a box 98 and a diaphragm chamber hermetically provided by a diaphragm 91 therein.
90 and a throttle valve 82 provided on the diaphragm 91
Of the operating pin 95 protruding toward the lever 83. The diaphragm chamber 90 is connected to the negative pressure pipe 89 via a nozzle 96. The compression spring 9 is provided between the diaphragm 91 and the rear wall of the box 98 via plates 93 and 94, respectively.
Arrange 2. The box body 98 is fixed to the vehicle body by a bracket 97.

Therefore, in the above idle up device, when a load is applied to the engine during idling, the engine speed decreases. Therefore, the negative pressure of the intake manifold downstream of the throttle valve decreases, the pressure of the diaphragm chamber 90 communicated by the negative pressure pipe 89 rises, and the pushing force of the compression spring 92 causes the diaphragm 91 to move.
Pushes the operating pin 95. As a result, the lever 83 is pushed, the opening of the throttle valve 82 is increased, the engine speed is improved, and the engine speed becomes appropriate.

That is, when the engine is lightly loaded, the negative pressure of the intake manifold is high, and as shown in FIG. 6, the pressure of the diaphragm chamber 90 is reduced and the diaphragm 91 is compressed by the compression spring 92.
And the actuation pin 95 is pulled backwards. As a result, the opening of the throttle valve 82 becomes smaller,
The engine speed will be appropriate.

Further, when the engine has a medium load, the negative pressure of the intake manifold is not so high. Therefore, as shown in FIG. 7, the pushing force of the compression spring 92 and the negative pressure cause the diaphragm to move.
The force with which 91 is pulled is in balance, and diaphragm 91 is almost in the neutral position. Therefore, the operating pin 95 holds the throttle valve 82 at a substantially intermediate opening between fully open and fully closed.
Note that FIG. 5 shows the state when the engine is stopped.

The above shows the operation of the idle-up device. The relationship between the throttle valve opening (degree) and the intake manifold negative pressure (mmHg) in this idle-up device characteristic is as shown in FIG. . That is,
The throttle valve opening is increased as the negative pressure becomes lower to prevent the engine speed from decreasing due to the load during idling.

[Problems to be solved]

However, if a sudden high load is applied to the engine during idling, there may be a delay in the operation path for opening the throttle valve through the negative pressure pipe, the diaphragm chamber and the operating pin. When such a delay occurs, the circuit of the throttle valve becomes unsuitable for the engine load, so that the engine stops, so-called engine stall occurs.

However, for example, in a forklift truck, the sudden high load during idling includes lift of the fork by operating the loading lever, forward tilting of the mast, operation of the power steering, and operation of the hydraulic brake.

In view of the above conventional problems, the present invention is to provide an idle-up device that does not stall even when a high load is suddenly applied during idling.

[Means for solving problems]

The present invention is directed to an intake manifold connected to a combustion chamber of an engine, a throttle valve for adjusting a ventilation path provided in the intake manifold, and an opening of the throttle valve corresponding to a negative pressure on the downstream side of the throttle valve. In an idle-up device including an actuator for controlling the degree and a negative pressure pipe for introducing a negative pressure, which is interposed between the actuator and the downstream side of the throttle valve, the actuator includes a box and a box inside the box. A first diaphragm chamber and a second diaphragm chamber that are airtightly separated by two diaphragms, and an operation pin that controls the opening of the throttle valve by combining the movements of the two diaphragms of the two diaphragm chambers. The first diaphragm chamber is connected to the negative pressure pipe via a switch valve capable of switching to atmospheric pressure. The second diaphragm chamber is connected to the negative pressure pipe, and the switch valve is electrically connected to a warning sensor for warning that a sudden high load will occur. When the switch is turned on, the switch valve is switched to the atmospheric pressure, and the first diaphragm chamber is immediately connected to the atmospheric pressure to perform the first stage throttle valve adjustment for driving the operating pin,
After that, when an actual high load occurs, the second stage throttle which maintains the first diaphragm chamber as it is at atmospheric pressure and drives the operating pin by setting the pressure in the negative pressure pipe that changes the second diaphragm chamber according to the load. The idle-up device is characterized by performing valve adjustment.

In the present invention, the actuator has a first diaphragm chamber and a second diaphragm chamber, and both chambers have a diaphragm that moves back and forth with a negative pressure change. An operating pin is arranged between the diaphragm and the lever of the throttle valve. Further, both the first diaphragm chamber and the second diaphragm chamber communicate with the negative pressure pipe, but the first diaphragm chamber has a switch valve between the first diaphragm chamber and the negative pressure pipe. The switch valve is a three-way valve that can be switched to the atmosphere side or the negative pressure side (that is, communicated with the negative pressure pipe) in response to the signal from the advance notice sensor.

In addition, the above-mentioned notice sensor is used for the operating portion that causes a sudden high load on the engine, for example, in the forklift, the above-mentioned cargo handling lever, power steering,
Install it on a hydraulic brake, etc. Further, as the notice sensor, a mechanical limit switch, a potentiometer,
There are sensors such as optical sensors. The warning sensor is
The operation of these operation parts is detected and the signal is transmitted to the switch valve.

[Work]

When the engine is idling and the fork is lifted by operating the cargo handling lever of a forklift, for example, a sudden load is generated on the engine. Therefore,
A warning sensor placed near the cargo handling lever detects this operation and sends the signal to the switch valve. Based on the signal, the switch valve communicates the valve with the atmosphere side and makes the pressure in the first diaphragm chamber equal to the atmospheric pressure. Therefore, the diaphragm pushes the operating pin connected to it and opens the throttle valve slightly. As a result, the first stage throttle valve adjustment is performed by the warning sensor.

Then, due to the operation of the cargo handling lever, a load is generated on the hydraulic pump and a sudden load is generated on the engine. Therefore, the negative pressure of the intake manifold decreases, and the pressure of the second diaphragm chamber communicating with the intake manifold via the negative pressure pipe increases (negative pressure decreases), and the diaphragm pushes the operating pin. Therefore, the throttle valve opens further. As a result, the second stage throttle valve adjustment is performed.

On the other hand, when the high load warning signal is not issued from the warning sensor, the first and second diaphragm chambers are both communicated with the negative pressure pipe, and like the conventional device, the negative load caused by the actual load is generated. Open and close the throttle valve in response to changes in pressure in the pressure pipe.

As described above, according to the present invention, the throttle valve is actuated in advance by the diaphragm of the first diaphragm chamber in accordance with the signal from the advance notice sensor (second valve).
Next, the second diaphragm chamber is operated with a decrease in the negative pressure of the intake manifold itself, and the throttle valve is finally set to an appropriate opening (Fig. 3).

[Effect]

As described above, in the present invention, the advance notice sensor causes the throttle valve to be slightly opened before a sudden load occurs, and then the final adjustment is performed. Therefore, according to the present invention, it is possible to provide an idle-up device in which engine stall does not occur even when a sudden high load is applied during idling.

〔Example〕

The idle-up device according to the embodiment of the present invention,
This will be described with reference to FIGS. 1 to 4. In this example, the idle-up device is mounted on a forklift.

The idle-up device of this example is, as shown in FIG.
An actuator having a first diaphragm chamber 10, a second diaphragm chamber 20, and an actuation pin 33, and a switch valve 4 connected to the actuator on the first diaphragm chamber 10 side.
A negative pressure pipe 89 communicating with the switch valve 4 and the second diaphragm chamber 20; and a warning sensor 51, 52, 53 (fourth
Figure) and.

The actuator is a first diaphragm chamber in which the inside of the box 30 is divided by two diaphragms 15 and 25.
It has 10 and a second diaphragm chamber 20. A plate provided on the back surface of the diaphragm 15 in the first diaphragm chamber 10.
The compression spring 11 is interposed between the plate 13 provided on the rear wall 301 of the box 30. In the second diaphragm chamber 20, a compression spring 21 is provided between a plate 23 provided on the back surface of the diaphragm 25 and a plate 22 provided on the front surface of the diaphragm 15.

The plate 23 is provided with an operating pin 33 facing the lever 83 of the throttle valve. Diaphragm 15,25
Are urged by the compression springs 11 and 21 in a direction to push out the operating pin 33.

Further, the first diaphragm chamber 10 is connected to the switch valve 4 via the nozzle 31 and the pipe 44, and the switch valve 4
Is connected to the negative pressure pipe 89 via the pipe 41. The negative pressure pipe 89 communicates with the negative pressure side of the intake manifold, as in the above-described conventional technique.

The switch valve 4 comprises a VSV (vacuum switch valve) 42 and a filter 43. The VSV 42 is the pipe 41 side (negative pressure side) or the filter 43 side (atmosphere side).
It is an electromagnetic three-way valve that communicates with either one of. The VSV42
Is activated by a signal from any of the warning sensors 51, 52, 53.

The other intake manifold 8 is the same as that of the above-mentioned conventional technique.

On the other hand, as shown in FIG. 4, the notice sensor is a notice sensor provided on the cargo handling lever 61 for raising and lowering the fork.
There are three: 51, a notice sensor 52 provided on the brake pedal 62, and a notice sensor 53 provided on the steering 64. Among them, the warning sensors 51 and 52 are limit switches,
The warning sensor 53 is a potentiometer. Further, these warning sensors 51 to 53 are electrically connected to the switch valve 4.

The notice sensor 51 is arranged so as to oppose the connecting rod 611 of the cargo handling lever 61 and the oil control valve 612. Oil control valve 612 is lift cylinder 61
3, and the flow dividing valve 63 are connected by hydraulic circuits. In addition,
The warning sensor 51 may be provided on the cargo handling lever rod of the tilt cylinder (not shown). Dividing valve 63 above
Is connected to the hydraulic pump 631 and the oil tank 632. The hydraulic pump 631 is driven by an engine (not shown).

The warning sensor 52 is a rod of the brake pedal 62.
It is arranged so as to face 621. The rod 621 corresponds to the diversion valve 63.
It is inserted into the master cylinder 622 connected to. The master cylinder 622 is connected to the brake 623.

Further, the warning sensor 53 is arranged so as to face the rod 640 between the steering 64 and the control valve 641. The control valve 641 is connected to the flow dividing valve 63 and the power steering 642 by hydraulic circuits.

Next, the function and effect of the idle up device of this example will be described.

First, when the engine is in the normal idling state, the engine is not particularly loaded, and neither warning sensor is in the on state.

Therefore, as shown in FIG. 1, the switch valve 4 communicates with the negative pressure pipe 89 via the pipe 41, while the second diaphragm chamber 20 always communicates with the negative pressure pipe 89. Therefore, both the first diaphragm chamber 10 and the second diaphragm chamber 20 are in a reduced pressure state due to the negative pressure of the intake manifold. Therefore, the diaphragms 15 and 25 retreat against the compression springs 11 and 21, and the operating pin 33 holds the lever 84 of the throttle valve at the neutral position (small throttle valve opening).

Next, as shown in FIG. 4, for example, when the cargo handling lever 61 is operated to lift the fork, the rod 611 turns on the limit switch of the warning sensor 51. Therefore, an electric signal is sent from the notice sensor 51 to the switch valve 4.

Therefore, as shown in FIG. 2, VS of the switch valve 4 is
The electromagnetic three-way valve of V42 is activated, cuts off communication with the negative pressure pipe 89, and communicates with atmospheric pressure through the filter 43. Therefore, the first diaphragm chamber 10 communicates with the atmospheric pressure via the switch valve 4, and as shown in FIG.
15 is pushed by the compression spring 11. As a result, the diaphragm 25 is also pushed by the compression spring 21 and the actuating pin 33 is pushed, and the opening of the throttle valve is slightly increased from that in the normal state. That is, the throttle valve adjustment in the first stage is performed by the signal from the warning sensor 51.

Then, as shown in FIG. 4, the oil control valve 612 is opened by the operation of the cargo handling lever 61, the hydraulic oil enters the lift cylinder 613, and the fork starts to rise. Therefore, a sudden load is applied to the oil pump 631 and a sudden load is applied to the engine, resulting in a decrease in the engine speed.

Therefore, the negative pressure of the intake manifold 8 is reduced, and the second diaphragm chamber remains in communication with the negative pressure pipe 89.
The pressure of 20 rises, and the diaphragm 25 is pushed by the compression spring 21 as shown in FIG. As a result, the operating pin
33 is pushed further, and the opening of the throttle valve becomes larger. That is, the second stage throttle valve adjustment is performed.

Next, when the load on the engine becomes small, such as when the fork is lowered, the second step is performed, and then the first step, contrary to the above.
Steps or both are performed simultaneously.

Further, although the above description has been made with respect to the operation of the cargo handling lever 61, also when the brake pedal 62 and the steering 64 are operated, the first diaphragm chamber 10 and the second diaphragm chamber 20 are similarly operated, and the two-stage throttle is operated. Valve adjustment is performed.

As described above, according to the device of this example, even if a sudden load is generated on the engine, the warning sensor 51-
This is detected by 53, the first diaphragm chamber 10 is operated by the switch valve 4, and then the second diaphragm chamber 20 is operated as in the conventional case. That is, the throttle valve is adjusted in two steps. Therefore, even if a sudden high load is applied during idling, no engine stall occurs.

[Brief description of drawings]

1 to 4 show an idle-up device of an embodiment,
Fig. 1 shows the state of the actuator during normal idling, Fig. 2 shows the state of the actuator at the first stage when the engine is loaded, Fig. 3 shows the state of the actuator at the second stage, and Fig. 4 shows the placement of warning sensors in each operating system Fig. 5 to Fig. 8 show a conventional idle-up device. Fig. 5 shows the actuator when the engine is stopped, Fig. 6 shows the light load of the engine, and Fig. 7 shows the actuator when the engine has a medium load. FIG. 8 shows the state, and FIG. 8 is an idle-up characteristic diagram. 10 …… First diaphragm chamber, 11,21 …… Compression spring, 15,25,91 …… Diaphragm, 20 …… Second diaphragm chamber, 33 …… Operating pin, 4 …… Switch valve, 51,52,53 …… Preliminary sensor, 8 …… Intake manifold, 82 …… Throttle valve, 83 …… Lever, 89 …… Negative pressure pipe,

Claims (1)

(57) [Claims] 1. An intake manifold connected to a combustion chamber of an engine, a throttle valve for adjusting a ventilation path provided in the intake manifold, and a throttle valve of the throttle valve corresponding to a negative pressure on a downstream side of the throttle valve. In an idle-up device including an actuator for controlling the opening and a negative pressure pipe for introducing negative pressure provided between the actuator and the throttle valve downstream side, the actuator includes a box body and a box body. A first diaphragm chamber and a second diaphragm chamber that are hermetically separated by two diaphragms; and an operating pin that controls the opening of the throttle valve by matching the movements of the two diaphragms of the two diaphragm chambers, The first diaphragm chamber is connected to the negative pressure piston via a switch valve that can be switched to atmospheric pressure. The second diaphragm chamber is connected to the negative pressure pipe, and the switch valve is electrically connected to a warning sensor for warning that a sudden high load will occur.
When the high load warning signal is issued, the switch valve is switched to the atmospheric pressure, the first diaphragm chamber is immediately connected to the atmospheric pressure, and the first stage throttle valve adjustment for driving the operating pin is performed. When a load is generated, the first diaphragm chamber is maintained at the atmospheric pressure as it is, and the second diaphragm chamber is adjusted to the pressure in the negative pressure pipe that varies according to the load, and the second stage throttle valve adjustment is performed to drive the operating pin. An idle up device characterized by the above.