JPH0357290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing control device for a fuel injection pump for a diesel engine, and in particular to a fuel injection timing control device that can improve the hydraulic response of a hydraulic actuator at low temperatures through computer control. This invention relates to a timing control device.

First, a conventional example will be explained with reference to FIG. 1. A fuel injection timing control device 1 that controls the fuel injection timing of a fuel injection pump (not shown) of a diesel engine (not shown) includes an actuator 2 operated by hydraulic pressure; Hydraulic control valve device 3 for the actuator
The system detects the operating condition of the engine and operates the actuator 2 by a computer (not shown) to control the fuel injection timing of the fuel injection pump. The hydraulic control valve device 3 is
A first poppet valve V ₁ and a second poppet valve V ₂ are connected in series between a hydraulic pressure supply source 4 and an oil tank 5 by an oil pipe 6. The actuator 2 is branched from the oil pipe 6 between the poppet valves V ₁ and V ₂ .
It is connected to the.

When the actuator 2 attempts to advance the fuel injection timing, the first poppet valve V ₁
The second poppet valve _V2 is closed and oil is supplied from the hydraulic supply source 4 through the oil pipes 6, 8 to the actuator 2. Conversely, when retarding, close the first poppet valve _V1 and open the second poppet valve V1.
poppet valve _V2 is opened, and the oil supplied to the actuator 2 is discharged into the oil tank 5 through the oil pipes 8 and 6.

However, when the injection timing is held constant, both poppet valves V ₁ and V ₂ are closed, so oil no longer flows through the oil pipes 6 and 8. Therefore, in cold weather when the viscosity of oil increases, the oil pipes 6, 8,
The oil trapped in the first and second poppet valves V ₁ and V ₂ and the actuator 2 exhibits considerable viscous resistance, and even if attempts are made to rapidly advance or retard the injection timing, This viscous resistance of the oil causes a time delay in the operation of the actuator 2, worsening the hydraulic response.
The drawback was that sufficient engine performance could not be obtained.

Furthermore, Japanese Patent Application Laid-Open No. 57-157024 discloses a hydraulic switching valve that constantly circulates oil pumped from a hydraulic source when the actuator is in the hold state. The purpose of the present application is to form an orifice with an extremely small cross-sectional area, and to provide passage resistance to the hydraulic pressure flowing through the orifice, thereby speeding up the rise of the hydraulic pressure when switching the valve. Inventions differ in their purpose, structure, and operation and effect. Further, in the conventional example, since pressure oil passes through the orifice, the amount of oil when the actuator is held is small, resulting in a drawback that the ability to warm the hydraulic control valve device in cold weather is small.

The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and its purpose is to constantly pass oil from a hydraulic supply source to a hydraulic control valve device by bypass in a hold state at injection timing. By circulating the oil, it prevents the viscosity of the oil from increasing even in cold weather, improves the hydraulic response during advance and retard operations, and enables appropriate injection timing. This also allows the performance of the diesel engine to be sufficiently enhanced even in cold weather. Another object of the present invention is to form a bypass having no orifice in the middle from one end of the shaft center of the valve body of the hydraulic control valve device to the other end;
The valve body is provided with a plurality of radial communication holes that communicate with the bypass and communicate with the internal space of the cylinder of the oil control valve device, and the internal space of the cylinder is configured to be connected to the actuator. The purpose of the present invention is to increase the flow rate of oil in a bypass during a hold state so that a separate hydraulic control device can be sufficiently warmed in cold weather.

In short, the present invention provides a fuel injection timing control device that includes an actuator operated by hydraulic pressure and a hydraulic control valve device for the actuator, and detects the operating condition of an engine to control the fuel injection timing of a fuel injection pump. , the hydraulic control valve device includes a bypass that constantly circulates oil pumped from a hydraulic supply source in a hold state in which the actuator does not perform advance or retard operations;
The bypass is formed by passing through the axial center of the valve body of the hydraulic control valve device from one end to the other end without providing an orifice in the middle, and communicates with the bypass to connect the cylinder of the hydraulic control valve device. The valve body is provided with a plurality of radial communication holes communicating with the internal space, and the internal space of the cylinder is communicatively connected to the actuator.

The present invention will be explained below based on embodiments shown in the drawings. What is shown in FIGS. 2 to 5 is a first embodiment of the present invention, in which a spool valve 9 is adopted as the hydraulic control valve device 13 of the fuel injection timing control device 1, and other configurations, That is, actuator 2,
The hydraulic pressure supply source 4 and oil tank 5 are the same as those in the conventional example shown in FIG. The spool valve 9 is provided with a first port P ₁ , a second port P ₂ and a third port P ₃ , and the first port P ₁ is connected to a hydraulic pressure supply source 4 .
The oil pipe 10 connected to the third
An oil pipe 11 connected to the oil tank 5 is connected to the port _P3 , and an oil pipe 1 connected to the actuator ₂ is connected to the second port P2.
2 are connected.

The spool valve consists of a cylinder 14 with a circular cross section and a valve body 15, and the valve body 15 has a first valve 15a, a second valve 15b, and a third valve 15c formed at predetermined intervals. A bypass BP is formed by penetrating from one end to the other end without providing an orifice in the middle. Further, a plurality of injection-shaped communication holes 15d communicating from the bypass BP to the internal space 14a of the cylinder 14 are provided between the first valve 15a and the second valve 15b.
A plurality of communication holes 15e are also provided between the third valve 5b and the third valve 15c. The bypass BP is configured to constantly circulate oil pumped from the hydraulic pressure supply source 4 in a hold state in which the actuator 2 does not advance or retard the angle.

The present invention is configured as described above, and its operation will be explained below. In FIGS. 2 and 3, when the actuator 2 is in the hold state, the valve body 15 of the spool valve 9
5a opens the first port _P1 , the second valve 15b closes the second port _P2 , and the third valve 15c opens the third port _P3 . Therefore, the hydraulic supply source 4
The oil pumped from the oil pipe 10, the first port P ₁ , the bypass BP of the valve body 15 of the spool valve 9, the third port P ₃ and the oil pipe 11
This state is maintained and the oil constantly circulates through the bypass BP.
Therefore, even in cold weather, oil at an appropriate temperature circulates through the hydraulic control valve device 13, so the viscosity of the oil does not become particularly high, and the actuator 2 is able to advance the angle.
Extremely good hydraulic response is obtained when attempting to perform a retard angle operation.

That is, when the actuator 2 performs the advance angle operation, the valve body 15 of the spool valve 9 moves to the right, the first valve 15a opens the first port P1, and the second port _P1 opens, as shown in FIG. Valve 15b opens the second port _P2 and third valve 15c closes the third port _P3 .
Therefore, the oil flowing through the oil pipe 10 enters the internal space 14 of the cylinder 14 from the first port _P1.
a, then enters the bypass BP of the valve body 15 and exits again to the internal space 14a from the communication hole 15d,
The oil is sent from the second port _P2 to the actuator 2 through the oil pipe 12, and the advance angle operation is quickly performed.

Next, when the actuator 2 performs a retard operation, as shown in FIG.
5 moves to the left, and the first valve 15a becomes the first port.
_P1 is closed, the second valve 15b opens the second port _P2 , and the third valve 15c opens the third port _P3 . Therefore, the oil flowing through the oil pipe 10 stops at the first port _P1 , and the oil supply stops.
Since the oil in the actuator 2 has a high pressure, the internal space 1 of the cylinder 14 is open to atmospheric pressure.
4a through the oil pipe 12,
The oil enters the bypass BP through the communication hole 15e, exits again into the internal space 14a, and is discharged from the third port _P3 through the oil pipe 11 into the oil tank 5, whereupon the retarding operation is performed quickly.

Since the present invention is configured and operates as described above, the oil from the hydraulic supply source is constantly circulated through the hydraulic control valve device through its bypass in the hold state at the injection timing. This has the effect of preventing the oil viscosity from becoming high even when the engine is in use, improving hydraulic response during advance and retard angle operations, and achieving appropriate injection timing. In addition, a bypass with no orifice is formed in the middle from one end of the shaft center of the valve body of the hydraulic control valve device to the other end, and is communicated with the bypass to connect to the internal space of the cylinder of the hydraulic control valve device. A plurality of reflective communication holes are provided in the valve body, and the internal space of the cylinder is connected to the actuator, so that the flow rate of oil in the bypass can be increased when the actuator is in the hold state, making it easier to use in cold weather. In this case, the hydraulic control valve device can be sufficiently warmed, and as a result, the performance of the diesel engine can be sufficiently improved even in cold weather.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of a conventional fuel injection timing control device, FIGS. 2 to 5 are examples of the present invention, FIG. 2 is an overall schematic diagram of the device, and FIG. 3 is a fuel injection timing control device. FIG. 4 is a vertical cross-sectional view of the spool valve in the timing hold state, FIG. 4 is a vertical cross-sectional view of the spool valve during advance angle operation, and FIG. 5 is a vertical cross-sectional view of the spool valve during retard angle operation. 1 is a fuel injection timing control device, 2 is an actuator, 4 is a hydraulic pressure supply source, 13 is a hydraulic control valve device,
BP is bypass.

Claims (1)

[Claims] 1. In a fuel injection timing control device comprising an actuator operated by hydraulic pressure and a hydraulic control valve device for the actuator, the fuel injection timing control device detects the operating condition of the engine and controls the fuel injection timing of the fuel injection pump. The valve device includes a bypass that constantly circulates oil pumped from a hydraulic supply source in a hold state in which the actuator does not perform advance or retard operations, and the bypass is connected to the axis of the valve body of the hydraulic control valve device. A plurality of radial communication holes are formed in the valve body from one end to the other end without providing an orifice in the middle, and communicate with the bypass and communicate with the internal space of the cylinder of the hydraulic control valve device. A fuel injection timing control device, wherein an internal space of the cylinder is communicatively connected to the actuator.