JP2502307Y2 - Fuel regulator for diesel engine with supercharger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fuel regulator for a diesel engine with a supercharger, which is mainly applied to automobiles.

[Prior Art] A distribution type fuel injection pump which is widely used in a diesel engine with a supercharger is provided as a prior art of the present invention.
For example, as disclosed in Japanese Patent Laid-Open No. 60-201029, a boost compensator for adjusting the fuel injection amount according to the supercharging pressure is usually provided. The boost compensator usually has a push rod, a diaphragm, and the like, and has its pressure chamber communicated with the intake passage via the pressure guiding passage. Then, when the boost pressure rises or falls, the push rod changes the relative position between the pump plunger and the spill ring via the control arm, the tension lever, etc. in the fuel injection pump, and the fuel injection is performed according to the boost pressure. It is designed to increase or decrease the amount.

Further, when the engine speed changes, the governor in the fuel injection pump shifts the tension lever and the like to adjust the fuel injection amount according to the engine speed.

[Problems to be Solved by the Invention] However, in the fuel injection pump of this type, the governor determines the fuel injection amount characteristic. For example, as shown in FIG. 4, when the fuel injection amount q is set to the required value q ₁ in consideration of the supercharging pressure in the high speed region, exhaust gas temperature, output, smoke, etc., the fuel injection amount q in the low speed region is required value q More than _one . Moreover, when acceleration is performed in the low speed range, the amount of fuel increase associated with the increase in boost pressure is added,
Excessive supply of fuel is likely to occur, and the amount of smoke produced tends to exceed the regulation value.

On the contrary, if the fuel injection amount is set in consideration of the output, smoke, etc. in the low speed range, the fuel becomes insufficient in the high speed range, resulting in a decrease in the output.

The present invention is intended to solve the above-mentioned problems.

[Means for Solving the Problems] The present invention employs the following means in order to achieve the above object.

That is, the fuel control device for a diesel engine with a supercharger according to the present invention comprises a boost compensator for adjusting the fuel injection amount according to the boost pressure, and a pressure guiding passage for guiding the boost pressure to the boost compensator. In a fuel control device for a diesel engine equipped with a supercharger, a pressure relief passage branched from the middle of the pressure guiding passage, and an on-off valve provided on the inlet side of the pressure relief passage to open and close the pressure relief passage, A throttle member provided on the outlet side of the pressure relief passage, and valve control means for opening the on-off valve in a low speed region where the engine speed is lower than a set value are provided.

[Operation] With such a configuration, the opening / closing valve is opened by the valve control means in the low speed range where the engine speed is lower than the set value, so that the pressure relief passage is opened. Therefore, the boost pressure of the supply air supplied to the engine,
The supercharging pressure introduced to the boost compensator via the pressure guiding passage is relieved from the pressure relief passage. At that time, the relief amount of the boost pressure is adjusted by the throttle member. As a result, when acceleration is performed, the fuel increase amount by the boost compensator is suppressed, and it is possible to suppress the occurrence of smoke due to a transient excess fuel supply.

When the engine speed exceeds the set value and reaches the high speed range, the valve control means closes the on-off valve and the pressure relief passage. At that time, the change in the supercharging pressure is immediately introduced to the boost compensator via the pressure guiding passage, so that the boost compensator adjusts the fuel in accordance with the change in the supercharging pressure.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

A fuel control device 1 for a diesel engine, which is schematically shown in FIG. 1, is adopted in an automobile having an exhaust turbine supercharger 2 which is a supercharger and a fuel injection pump 3 of a distribution type.

The exhaust turbine supercharger 2 includes a compressor and a turbine (not shown). When the supercharging pressure exceeds a set pressure in the high load range, the actuator opens the waste gate valve to bypass the exhaust gas to the turbine. It is designed to be discharged.

The fuel injection pump 3 is substantially the same as a normal one having a feed pump (not shown), a governor, and a spill ring slidably mounted on a pump plunger (not shown), and includes a boost compensator 4. The boost compensator 4 has a well-known structure. That is, the internal space is divided into a pressure chamber and an atmospheric pressure chamber by a diaphragm (not shown), and the base end of the push rod is fixed to the diaphragm, which is fixed to the pump housing. A taper-shaped cam surface that widens toward the tip side is formed at the tip portion of the push rod, and the tip portion faces the inside of the pump housing and is brought into contact with the tip of the connecting pin. The base end of the connecting pin is fixed to one end of the control arm. The control arm is rotatable about a shaft fixed to the pump housing within a certain range, and the other end is in contact with one end of the tension lever. The tension lever, together with the control lever, can rotate within a certain range around a common shaft fixed on the guide lever as a fulcrum. The control lever is in contact with the tip of the governor sleeve, and the tip is connected to the spill ring via a pin.

The fuel control device 1 is provided in the boost compensator 4, a pressure guiding passage 5 that guides a boost pressure to the boost compensator 4, a pressure relief passage 6 branched from the middle of the pressure guiding passage 5, and a pressure relief passage 6. An electromagnetic valve 7 as an opening / closing valve and a jet 8 as a throttle member are provided.
The pressure guide passage 5 connects the downstream side of the compressor in the intake passage 9 with the pressure chamber of the boost compensator 4. The inlet 6a of the pressure relief passage 6 has a pressure guiding passage 5
The air cleaner is opened near the inlet of the
It opens to the intake passage 9 between the compressor 10 and the compressor. The electromagnetic valve 7 is configured to open and close ON / OFF and is connected to a control box 11 which is a valve control means. The engine rotation signal a is input to the control box 11 from the drive shaft of the fuel injection pump 3. Then, when the engine speed is equal to or lower than the set value n, the control signal b is output to open the electromagnetic valve 7.

With such a configuration, in the low speed range where the engine speed is equal to or lower than the set value n, the electromagnetic valve 7 is opened and the pressure relief passage 6 is opened. The supercharging pressure guided to the pressure chamber of the boost compensator 4 via the pressure guiding passage 5 is relieved from the pressure relief passage 6. At that time, the relief amount of the supercharging pressure is adjusted by the jet 8. As a result, when acceleration is performed, the fuel amount increase by the boost compensator 4 is suppressed.

On the other hand, when the engine rotation speed exceeds the set value n and shifts to the high speed range, the pressure relief passage 6 is closed by the electromagnetic valve 7, so that the boost pressure is not relieved and the engine and boost compensator 4 are not relieved. Led to the pressure chamber. In this case, the exhaust turbine supercharger 2
A known fuel adjustment is made in response to the supercharging effect of For example, when the supercharging pressure rises, the push rod of the boost compensator 4 is pushed out, and the connecting pin that is in contact with the cam surface of the boost compensator 4 is displaced. Move. As a result, the spill ring slides in the direction of increasing fuel, the effective stroke from the start of fuel pumping to the end of fuel pumping by the pump plunger increases, and the fuel injection amount increases. When the supercharging pressure decreases, an operation reverse to the above operation is performed, and the fuel injection amount is reduced according to the decrease in the supercharging pressure.

Therefore, with such a configuration, as shown in the comparison diagram of FIG. 2, it is possible to effectively adjust the supercharging pressure and the fuel injection amount q in the low speed range as compared with the conventional one. Therefore, the amount of smoke generated due to excessive fuel supply can be effectively suppressed.

Further, in the high speed region, the fuel injection is performed according to the preset required value, so that the amount of smoke generated in the high speed region can be suppressed.

Moreover, according to such a configuration, it is not necessary to reset the fuel injection amount characteristic by the governor, and the boost compensator 4 provided in the fuel injection pump 3 can be effectively used. Therefore, the device does not become large-scale, and the cost does not increase significantly.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment. For example, it is possible to change the diameter of the throttle member to adjust the boost pressure acting on the boost compensator.

The control box can be replaced by a microcomputer unit. In this case, it is also possible to widen the control range of the supercharging pressure by opening / closing the opening / closing valve based on the engine rotation.

Further, the fuel adjustment device may be configured as shown in FIG. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals, and their explanations are omitted. In this embodiment, a three-way switching valve 12 consisting of a solenoid valve is provided on the inlet side of the pressure guiding passage 5.
And the port of the three-way selector valve 12 shift switch
This is a case in which the control box 11 performs switching control based on the output signal c of 13. The three-way switching valve 12 has the input port 12a connected to the intake passage 9 side, and
The first output port 12b is connected to the boost compensator 4 side, and the second output port 12c is connected to the intake passage 9 upstream of the compressor. Shift switch 13
Outputs a signal c when the transmission (not shown) is in the first speed or in the reverse position. Control box
When the signal c is input, the reference numeral 11 outputs the signal d to the three-way switching valve 12 to close the first output port 12b, and at the same time, the input port 12a and the second output port 12c.
It is set to communicate with and. When the signal c is not input, the second output port 12c is closed,
The input port 12a and the first output port 12b are set to communicate with each other.

Thus, according to such a fuel control device 1, the boost pressure introduced into the boost compensator 4 can be adjusted in the low speed range as described above, and the boost compensator 4 can be used when the transmission has a low gear ratio. The fuel increase due to can be stopped. That is, when the transmission has a low gear ratio, more torque than necessary acts on the drive system such as the transmission and the differential mechanism. Therefore, it is possible to suppress an increase in fuel and suppress an increase in torque within a range that does not adversely affect traveling, and reduce the load on the drive system.

[Advantages of the Invention] Since the present invention has the above-described configuration, the fuel injection amount in the low speed range can be appropriately adjusted without changing the structure of the fuel injection pump. As a result, it is possible to effectively reduce the amount of smoke generated in the low speed range without causing a reduction in the output in the high speed range.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a diagram schematically showing the entire structure, and FIG. 2 is a comparative diagram. FIG. 3 is an overall view corresponding to FIG. 1 showing another embodiment of the present invention. FIG. 4 is a diagram for explaining a defect in the conventional example. 1 ... Fuel control device for diesel engine 2 ... Supercharger (exhaust turbine supercharger) 3 ... Fuel injection pump 4 ... Boost compensator 5 ... Pressure guide passage 6 ... Pressure relief passage 6a ... Inlet 6b ...... Outlet 7 …… Open / close valve (solenoid valve) 8 …… Throttle member (jet) 11 …… Valve control means (control box)

Claims (1)

(57) [Scope of utility model registration request] 1. A fuel control device for a diesel engine with a supercharger, comprising: a boost compensator for adjusting a fuel injection amount according to a supercharging pressure; and a pressure guide passage for guiding the supercharging pressure to the boost compensator. A pressure relief passage branched from the middle of the pressure guiding passage, an on-off valve provided at an inlet side of the pressure relief passage for opening and closing the pressure relief passage, and a throttle member provided at an outlet side of the pressure relief passage. And a valve control means for opening the on-off valve in a low speed range where the engine speed is lower than a set value, the fuel adjusting device for a diesel engine with a supercharger.