JPH0533690A - Auto-throttle device for industrial vehicle - Google Patents

Abstract

PURPOSE:To prevent an engine from stalling by maintaining an idling speed still higher at a time when a temperature of operating oil is low even after warm-up is over. CONSTITUTION:In an industrial vehicle with farm working machinery operating by discharge pressure of an operating oil pump 12 being driven by an engine 14, there is provided a hydraulic valve 6 which is operated at a time when a temperature of operating oil being discharged out of the operating oil pump 12 is lower than the preset oil temperature. A throttle valve 3 of the engine 14 is made so as to be controlled by this hydraulic valve 6, so that since an idling speed is still maintainable higher even after the warm-up, such a possibility that the engine might be inadvertently stopped is thus preventable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic throttle device for an industrial vehicle in which the idling speed of an engine is controlled according to the temperature of hydraulic oil.

[0002]

2. Description of the Related Art Some conventional industrial vehicles having hydraulically driven working machines are equipped with a gasoline engine. Normally, a gasoline engine has a drawback that starting performance is poor in cold weather because the vaporization of gasoline is not sufficient until the engine warms up.

In order to remedy the above-mentioned drawbacks, in the past, at the time of engine startup, the choke valve of the carburetor was operated in the closing direction to perform warm-up operation, and when the engine warmed up, an automatic choke for operating the choke valve in the opening direction was used. Is attached to. Further, the above conventional auto choke is configured to operate when the temperature of the engine cooling water is detected by a temperature detector utilizing expansion or contraction of wax or the like and the temperature of the cooling water is equal to or lower than a preset temperature. ing.

[0004]

However, in an industrial vehicle having a hydraulically driven working machine, hydraulic oil is circulated in the hydraulic circuit even during warm-up operation of the engine. Since the temperature rises slowly, even if the temperature of the cooling water reaches the preset temperature and the warm-up operation of the engine is completed, the temperature of the hydraulic oil flowing through the hydraulic circuit is low and the viscosity is high. A large load acts on the engine that drives the hydraulic oil pump due to the resistance.

As a result, even if the warm-up operation is completed by the auto choke, the engine is stopped due to the load of the hydraulic oil pump. The present invention has been made for the purpose of improving the above problems, and provides an automatic throttle device for an industrial vehicle, which controls the idling speed of an engine according to the oil temperature of hydraulic oil, and provides This is to prevent the engine from being stopped accidentally.

[0006]

In order to achieve the above object, the present invention provides an industrial vehicle having a working machine which operates by the discharge pressure of a hydraulic oil pump driven by an engine, and discharges from the hydraulic oil pump. A hydraulic valve that operates when the oil temperature of the hydraulic oil is lower than a preset oil temperature is provided, and the throttle valve of the engine is controlled by this hydraulic valve.

[0007]

With the above structure, even if the engine warm-up operation is completed, the idling rotation is maintained at a value higher than the normal idling speed when the oil temperature of the hydraulic oil is low and the flow path resistance is large, so the engine is not prepared. Never stop.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings shown in FIGS. 1 is a block diagram of an auto throttle device, FIG. 2 is a sectional view of a hydraulic valve, and FIG. 3 is A of FIG.
FIG. 4 is a diagram showing the relationship between the flow path resistance of the hydraulic system and the oil temperature, as viewed from the direction of the arrow.

In the above drawing, 1 is an engine 14 which will be described later.
The carburetor has a choke valve 2 and a throttle valve 3, and the throttle valve 3 can be opened and closed by a throttle lever 4. The throttle lever 4 is biased in the closing direction of the throttle valve 3 by a spring 5, and the tip of the throttle lever 4 is in contact with the tip of a spool 6b of a hydraulic valve 6.

As shown in FIGS. 2 and 3, the hydraulic valve 6 has a valve body 6a fixed to the engine 14 or the like by a bracket. Inside the valve body 6a, the spool 6b and a tubular retainer 6c are provided. Is housed. The retainer 6c is screwed onto the inner peripheral surface of the valve body 6a, and by rotating the square tube portion 6d protruding from the end of the valve body 6a, the retainer 6c can be moved and adjusted in the axial direction of the valve body 6a. Has become.

The spool 6b is movably accommodated in the center of the retainer 6c. One end of the spool 6b is projected outward from the end face of the square tube portion 6d of the retainer 6c, the tip is in contact with the tip of the throttle lever 4, and the spring seat 6e is in contact with the other end. The end of the compression spring 7 housed in the retainer 6c is in contact with the spring seat 6e.

The other end of the spool 6b is fitted in a pressure receiving chamber 6f formed inside the fixed end of the valve body 6a. An annular groove 6g is formed on the outer peripheral surface of the spool 6b fitted in the pressure receiving chamber 6f.
The O-ring 8 and the backup ring 9 are housed therein, and the pressure receiving chamber 6f is connected to the discharge side pipe line 13 of the hydraulic oil pump 12 by the pipe line 10 connected to the end of the valve body 6a. .

The hydraulic oil pump 12 is driven by an engine 14, and the discharge pressure is supplied to a flow divider 15 by a pipe line 13, and is divided into two lines by the flow divider 15. There is. One of the divided discharge pressures is supplied to the steering system 16 for the steering operation, and the other is supplied to the working machine system 17. The work machine system 17 has a work machine operation valve 18, and the work machine operation valve 18 supplies hydraulic pressure to an actuator 19 of a work machine (not shown) to drive the work machine.

The operation will now be described. When the engine 14 is started in cold weather or the like, the discharge pressure of the hydraulic oil pump 12 driven by the engine 14 changes the steering system 16 and the working machine system 1.
7 is supplied to the pressure receiving chamber 6f of the hydraulic valve 6 through the conduit 10. Since the viscosity of the above hydraulic oil is high when the temperature is low, the flow passage resistance when flowing through the hydraulic circuit is large, and as the temperature rises, the viscosity becomes lower and the flow passage resistance also becomes smaller. Is as shown in FIG.

That is, when the oil temperature is low, such as during cold weather, the flow path resistance is large, so the discharge pressure P of the hydraulic oil pump 12
Is large even with no load, and this hydraulic pressure P is the hydraulic valve 6
Is supplied to the pressure receiving chamber 6f. In the hydraulic valve 6, the spring force of the compression spring 7 is set in advance so that the spool 6b responds to the hydraulic pressure P1 due to the flow path resistance generated when the oil temperature becomes lower than the set temperature t1. When the oil temperature is lower than the set temperature t1, the spool 6b is pushed toward the throttle lever 4 by the hydraulic pressure P1, and the throttle valve 3 is opened. As a result, the idle speed of the engine 14 during the warm-up operation is automatically controlled according to the oil temperature of the hydraulic oil.

Even if the warm-up operation of the engine 14 is completed, if the oil temperature of the working oil does not become higher than the set temperature t1, the idle speed of the engine is continuously controlled according to the oil temperature of the working oil, and When the set temperature t1 is exceeded, the hydraulic pressure P1 generated by the flow path resistance also decreases, and the spool 6b is returned to its original position by the action of the compression spring 7, whereby the idling speed of the engine 14 also rotates during warm-up operation. Becomes a number.

Even if the flow path resistance of the hydraulic circuit changes depending on the vehicle type or the carburetor specifications change depending on the engine, the retainer 6c of the hydraulic valve 6 is rotated to adjust the stroke s of the spool 6b, which is applied to these. be able to. Further, although the gasoline engine is described in the above embodiment, the same can be applied to a diesel engine.

[0018]

As described above in detail, the present invention controls the idling speed of the engine by operating the throttle valve of the engine according to the oil temperature of the hydraulic oil. Like the start of
Even if the engine warm-up operation is completed, if the oil temperature of the hydraulic oil is low, the idling speed will continue to be maintained at a high value, preventing the engine from accidentally stopping due to the load on the hydraulic oil pump. Will be able to.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an automatic throttle device for an industrial vehicle according to an embodiment of the present invention.

FIG. 2 is a sectional view of a hydraulic valve.

FIG. 3 is a view from the direction A in FIG.

FIG. 4 is a diagram showing a relationship between a flow path resistance of a hydraulic circuit and an oil temperature of hydraulic oil.

[Explanation of symbols]

3 Throttle valve 6 hydraulic valve 6b spool 12 hydraulic pump 14 engine

Claims (2)

[Claims] 1. In an industrial vehicle having a working machine that is operated by the discharge pressure of a hydraulic oil pump 12 driven by an engine 14, the oil temperature of the hydraulic oil discharged from the hydraulic oil pump 12 is a preset oil temperature. An automatic throttle device for an industrial vehicle, characterized in that a hydraulic valve 6 that is operated at a lower temperature is provided, and the throttle valve 3 of an engine 14 is controlled by the hydraulic valve 6. 2. The automatic throttle device according to claim 1, wherein the stroke of the spool 6b of the hydraulic valve 6 is adjustable.