JP2747592B2 - Fuel injection device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device for an internal combustion engine that supplies fuel to the internal combustion engine.

2. Description of the Related Art An internal combustion engine is provided with a fuel injection device. In the fuel injection device, a fuel passage is provided in a fuel tank, and a fuel pump is disposed in the middle of the fuel passage. A fuel injection valve that opens when the pressure on the downstream side is high and that returns the fuel on the downstream side of the fuel pump to the upstream side, and injects an amount of fuel corresponding to the operation state. Is disposed in the fuel passage downstream of the fuel pump, and includes a fuel injection valve drive circuit that controls the pulse width of a drive signal for driving the fuel injection valve according to the operating state. Is driven in accordance with the operation state, and the amount of fuel corresponding to the operation state is injected. Also,
During the period in which the fuel injection valve is closed without the pulse of the drive signal reaching, the fuel passage downstream of the fuel pump is closed, and when the pressure on the downstream side increases, the pressure regulating valve opens, and the fuel pump is opened. So that excessive load does not act on it.

In addition, such a fuel injection device includes, for example, a circuit connected to a resistor and a circuit bypassing the resistor in order to change the discharge capacity of the fuel pump. In some cases, the discharge capacity is reduced by driving the drive, and the discharge capacity is increased by driving the circuit in a high rotational speed region by bypassing a resistor.

[Problems to be Solved by the Invention] By the way, in order to be able to inject the maximum amount of fuel according to the operation state, it is necessary to set a large discharge amount of the fuel pump. However, when injecting the minimum amount of fuel according to the operation state, most of the discharge amount of the fuel pump returns from the pressure regulating valve to the upstream side of the fuel pump, and the fuel pump circulates the fuel unnecessarily. It will be. This not only wastes energy but also raises the temperature of the circulating fuel.

Further, the switching of the discharge capacity of the fuel pump is performed by using two circuits, a circuit connecting a resistor and a circuit bypassing the resistor, and the circuit configuration is complicated because there are many circuit elements. The discharge capacity of the fuel pump is switched in two stages, and in order to perform further switching,
There is a problem that a resistor corresponding to the number of switching stages is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple circuit configuration, and is capable of stably changing a discharge pressure of a fuel pump in accordance with an operation state, and expanding a dynamic range of a fuel injection amount. It is an object to provide a fuel injection device.

[Means for Solving the Problems] In order to solve the problems and achieve the object, the invention according to claim 1 provides a fuel passage in a fuel tank and arranges a fuel pump in the middle of the fuel passage. A pressure regulating valve that opens when the pressure on the downstream side is high and returns the fuel on the downstream side of the fuel pump to the upstream side is disposed on the downstream side of the fuel pump in the fuel passage, corresponding to the operating state. A fuel injection valve for injecting a predetermined amount of fuel in the fuel passage downstream of the fuel pump, and controlling a pulse width of a drive signal for driving the fuel injection valve in accordance with an operation state. In a fuel injection device for an internal combustion engine equipped with a valve drive circuit,
The drive power supplied to the fuel pump per hour is small in a low rotation or low load range, and large in a high rotation or high load range, and the pressure control valve is set to open when the pressure control valve is opened. The present invention is characterized in that an actuator is provided which adjusts the valve force to be small in a low rotation or low load range and to be large in a high rotation or high load range.

According to the first aspect of the present invention, the discharge amount of the fuel pump is increased or decreased in accordance with the fuel injection amount required by the internal combustion engine corresponding to the operating state, so that the fuel pump consumes no energy. In addition, since the discharge amount of the fuel pump itself is increased or decreased, the fuel pump does not waste energy in a wider operating state. Further, since the pressure in the fuel passage downstream of the fuel pump is increased or decreased in accordance with the operating state, the injection amount can be increased or decreased by controlling the injection pressure. That is, the dynamic range of the injection amount can be expanded in addition to the increase and decrease of the injection amount by controlling the opening period of the fuel injection valve, and the fuel injection valve can be downsized accordingly.

According to a second aspect of the present invention, the fuel injection device for an internal combustion engine according to the first aspect corresponds to a difference between a pressure downstream of the fuel pump in the fuel passage and a pressure near a portion where fuel is injected. When the valve opening force is greater than the set valve opening force, the pressure regulating valve is opened.

According to the second aspect of the present invention, the injection pressure is determined by feeding back the pressure of the injection destination, and the injection is performed with the difference between the injection pressure and the pressure of the injection destination kept constant. As a result, a stable amount of fuel can be injected even if the pressure fluctuates at the injection destination.

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

FIG. 1 is a schematic diagram of a fuel injection device for an internal combustion engine to which the present invention is applied.

The fuel tank 1 is provided with a fuel passage 2. The fuel passage 2 is provided with a fuel pump 3 for pumping the fuel stored in the fuel tank 1, a fuel filter 4 for filtering the fuel, and a damper for absorbing pressure fluctuation of the fuel. 5. A pressure regulating valve 6 for regulating the pressure of the fuel to a constant value is provided, so that fuel of a constant pressure is supplied to an electromagnetic fuel injection valve 8 provided in an intake passage 7 of the internal combustion engine.

The fuel pump 3 is driven by a pump drive circuit 11 controlled by a control circuit 10 provided in the control unit 9, and changes the discharge capacity of the fuel pump 3 according to the operation state of the internal combustion engine, and changes the pressure of the fuel passage 2. Can be adjusted.

The control circuit 10 changes the duty ratio of the drive signal, and changes the drive power for driving the fuel pump 3 via the pump drive circuit 11. For example, a fuel consumption discrimination map based on the load and the engine speed as shown in FIG. 2 is stored in advance in the control circuit 10, and according to this discrimination map, the fuel consumption is calculated in the small area A and the large area B. Is determined. When the fuel injection amount is in the small area A, an intermittent drive signal is output as shown in FIG. 3, and when the fuel consumption is in the large area B, a continuous drive signal is output.

The pump drive circuit 11 opens and closes, for example, a switching circuit in response to the drive signal, and changes the current value flowing through the fuel pump 3 to change the discharge capacity of the fuel pump 3 as shown in FIG. That is, the driving power supplied to the fuel pump 3 per hour is small in a low rotation or low load region and is large in a high rotation or high load region. Since the discharge amount of the fuel pump is increased or decreased in accordance with the fuel injection amount required by the internal combustion engine corresponding to the operation state, the fuel pump does not waste energy.

The fuel injection valve 8 is driven by an injection valve drive circuit 12 controlled by a control circuit 10, controls a pulse width of a drive signal in accordance with an operation state of the internal combustion engine, and injects a predetermined amount of fuel into the intake passage 7. Thus, the air-fuel mixture is supplied to the internal combustion engine 13 side.

The downstream side of the fuel injection valve 8 in the intake passage 7 is communicated with the pressure regulating valve 6 through a pipe 14, and the pipe 14 is further provided with an intake pressure detector 15. When the pressure difference between the intake passage 7 and the fuel passage 2 becomes equal to or greater than a predetermined value, the pressure regulating valve 6 is opened to connect the fuel passage 2 with the fuel tank 1, and the pressure of the intake passage 7 and the fuel passage 2 Is automatically and always maintained at a predetermined value.

The pressure adjusting valve 6 is provided with an actuator 16 for adjusting a valve opening force of the valve.
It is driven by an adjustment valve drive circuit 17 controlled by 10. As a result, the pressure regulating valve 6 changes the valve opening force according to the operating state of the internal combustion engine. For example, the pressure of the fuel is reduced in a low rotation or low load range, and is increased in a high rotation or high load range. Can be controlled.

That is, the pressure regulating valve 6 is provided with an actuator 16 that adjusts the set valve opening force when the pressure regulating valve 6 is opened to be small in a low rotation or low load region and large in a high rotation or high load region. As described above, since the discharge amount of the fuel pump 3 itself is increased or decreased, the fuel pump 3 does not waste energy in a wider operation state. Further, since the pressure in the fuel passage downstream of the fuel pump 3 is increased or decreased in accordance with the operating state, the injection amount can be increased or decreased by controlling the injection pressure. That is, the dynamic range of the injection amount can be expanded in addition to the increase and decrease of the injection amount by controlling the opening period of the fuel injection valve 8, and the size of the fuel injection valve 8 can be reduced accordingly.

When the valve opening force corresponding to the difference between the pressure on the downstream side of the inner fuel pump 3 in the fuel passage and the pressure near the portion where fuel is injected is larger than the set valve opening force, the pressure regulating valve 6 is turned off. It is designed to be open, the injection pressure is determined by feeding back the pressure of the injection destination, and the injection is performed with a constant pressure difference between the injection pressure and the injection destination.
A stable amount of fuel can be injected.

A throttle valve 18 is provided upstream of the fuel injection valve 8, and an air cleaner 19 is further provided upstream thereof. The air cleaner 19 is provided with an intake air temperature detector 20.
Further, the throttle valve 18 is provided with a throttle position detector 21 so that the opening of the throttle valve 18 can be detected.

The crankshaft 23 connected to the piston 22 of the internal combustion engine 13 is provided with a projection 24. The engine speed detector 25 detects the engine speed from the crank position and the rotation speed of the projection 24. Detects the position of the camshaft 27.

The opening and closing of the combustion chamber 28 and the intake passage 7 of the internal combustion engine 13 is controlled by an intake valve 29.
The opening and closing of the combustion chamber 28 and the exhaust passage 30 is performed by an exhaust valve 31, and the intake valve 29 and the exhaust valve 31 are respectively opened and closed at a predetermined timing. Is provided with an engine temperature detector 32.

These intake pressure detector 15, intake air temperature detector 20,
Operation information obtained by the throttle position detector 21, the engine speed detector 25, the camshaft position detector 26, and the engine temperature detector 32 is input to the control circuit 10 of the control unit 9, and the fuel pump is operated based on the operation information. 3. Control of the fuel injection valve 8 and the pressure regulating valve 6 is performed.

Therefore, when the main switch of FIG. 3 is input, the control circuit 10 of the control unit 9 outputs a drive signal, drives the fuel pump 3 via the pump drive circuit 11 for a predetermined time, and reduces the pressure in the fuel passage 2. At a predetermined value, the fuel is kept at an appropriate pressure when the internal combustion engine 13 is operating.

Then, the internal combustion engine 13 is started, and for example, when the engine speed is low or the engine load is low during idling or the like, a fuel consumption determination map as shown in FIG. Is performed, the fuel consumption is determined to be in the small area A, and an intermittent drive signal is output as shown in FIG. Therefore, the fuel pump 3 is driven by the pump drive circuit 11.
Of the fuel pump 3 is reduced, the discharge capacity of the fuel pump 3 is reduced, and the fuel injection valve 8 is operated in a state where the fuel pressure is reduced.

On the other hand, for example, in the high rotation or high load region of the internal combustion engine 13, the fuel consumption is determined to be in the large region B by the fuel consumption determination map shown in FIG. Output drive signal. Therefore, the pump drive circuit 11
As a result, the driving power of the fuel pump 3 increases, the discharge capacity of the fuel pump 3 increases, and the fuel injection valve 8 operates in a state where the fuel pressure increases.

[Effects of the Invention] As described above, according to the first aspect of the present invention, the drive power supplied to the fuel pump per hour is reduced in a low rotation or low load region, and increased in a high rotation or high load region, and the pressure is increased. The set valve opening force when the regulating valve is opened is small at low rotation or low load range and large at high rotation or high load range. In addition, since the discharge amount of the fuel pump is increased or decreased, the fuel pump does not waste energy. In addition, since the discharge amount of the fuel pump itself is increased or decreased, the fuel pump does not waste energy in a wider operating state. Furthermore, since the pressure in the fuel passage downstream of the fuel pump is increased or decreased in accordance with the operating state, the injection amount can be increased or decreased by controlling the injection pressure, and the injection amount can be increased or decreased by controlling the opening period of the fuel injection valve. In addition to this, the dynamic range of the injection amount can be expanded, and the size of the fuel injection valve can be reduced accordingly.

According to the second aspect of the present invention, when the valve opening force corresponding to the difference between the pressure on the downstream side of the fuel pump in the fuel passage and the pressure near the portion where fuel is injected is larger than the set valve opening force. ,
Since the pressure regulating valve is opened, the injection pressure is determined by feeding back the pressure of the injection destination, and the injection is performed with a constant difference between the injection pressure and the pressure of the injection destination. Thus, a stable amount of fuel can be injected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a fuel injection device of an internal combustion engine to which the present invention is applied, FIG. 2 is a fuel consumption discrimination map, and FIG. 3 is a timing chart showing the operation of the fuel injection device. In the figure, reference numeral 1 denotes a fuel tank, 2 denotes a fuel passage, 3 denotes a fuel pump, 6 denotes a pressure regulating valve, 7 denotes an intake passage, 8 denotes a fuel injection valve,
9 is a control unit, 10 is a control circuit, and 11 is a pump drive circuit.

Claims (2)

(57) [Claims] 1. A fuel passage is provided in a fuel tank, a fuel pump is disposed in the middle of the fuel passage, and a valve is opened downstream of the fuel pump in the fuel passage when the pressure on the downstream side is high. A pressure regulating valve for returning fuel on the downstream side of the fuel pump to the upstream side is disposed, and a fuel injection valve for injecting an amount of fuel corresponding to an operation state is disposed in the fuel passage on the downstream side of the fuel pump. In a fuel injection device for an internal combustion engine including a fuel injection valve drive circuit that controls a pulse width of a drive signal for driving the fuel injection valve in accordance with a state, a supply driving power per time to the fuel pump is reduced. , Small in low rotation or low load region, large in high rotation or high load region, the pressure regulating valve, the set valve opening force when this pressure regulating valve is opened is small in low rotation or low load region, High rotation or high load In large it an adjustment actuator is provided a fuel injection system for an internal combustion engine characterized by. 2. The set valve opening force according to claim 1, wherein a valve opening force corresponding to a difference between a pressure of the fuel passage downstream of the fuel pump and a pressure near a portion where fuel is injected is provided. The fuel injection device for an internal combustion engine, wherein the pressure regulating valve is opened when the pressure becomes larger.