JPH0115687B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boost compensator, and an object of the present invention is to reduce acceleration smoke (black smoke) without reducing the low-speed torque starting performance of a turbocharged engine.

A boost compensator is an automatic fuel injection amount adjustment device that is attached to the fuel injection pump of a turbocharged engine, and when the amount of intake air sent to the engine cylinder increases due to the action of the turbocharger, it discharges an appropriate injection amount commensurate with the increase in intake air amount sent to the engine cylinder. This is a device that controls the control rack to achieve complete engine combustion and increase output. In other words, when the engine speed increases and the internal pressure of the engine's intake pipe increases due to the action of the turbocharger, the boost pressure is guided to the pressurizing chamber of the boost compensator, and the control rack is increased in fuel by a linkage mechanism based on the operation of the diaphragm. The fuel is supercharged by moving the fuel in the direction of the fuel.

However, according to the conventional boost compensator, as is clear from the graph in Figure 2, the rack position in the no-load state is shown by line A, and when starting from idling a or revving, the boost pressure suddenly increases. The rack position rapidly responds in the direction of fuel increase as shown by _B1 , and as a result, free acceleration smoke is discharged in the range indicated by the diagonal line b. If this free acceleration smoke is reduced by a boost compensator, there is a problem that low-speed torque is insufficient and starting performance becomes poor.

The present invention provides a boost compensator that solves these conventional problems, and its features are that it is equipped with a dart pot function that suppresses the operation of the diaphragm due to a sudden increase in boost pressure; As shown in the graph of the figure, a time delay S is given to the movement of the rack in the fuel increasing direction, so that the rack moves slowly as indicated by the dotted line _B2 .

Embodiments of the present invention will be described below with reference to FIG. 1 is a fuel injection pump, 2 is a governor, and 3 is a rack, which is moved in the direction of increasing or decreasing fuel by the governor 2 depending on the engine rotation speed. 4 is a boost compensator according to the present invention. Its structure is such that the inside of the casing 19 is divided into two chambers by a first diaphragm 5, one of which is a boost pressure chamber 6 that communicates with the intake manifold and leads boost pressure from a boost inlet 8, and the other is an atmospheric pressure chamber 7 communicating with the atmosphere through a hole 9. A second diaphragm 12 is provided within this atmospheric pressure chamber 7, and a push rod 14 is fixed to this second diaphragm 12.
10 is a return spring of the first diaphragm 5, and 13 is a return spring of the second diaphragm 12.

One end of the push rod 14 abuts against an abutment member 18 attached to the first diaphragm 5, and the other end extends through the casing 19 and projects into the governor 2. A clearance 15 is formed in the penetrating portion of the casing 19 and has a throttling effect that communicates the space 18 defined by the second diaphragm 12 with the outside air. An engaging surface 16 is provided at the protruding end of the push rod 14. This engagement surface 16 engages with one end 17b of an arm 17 pivotally attached to the governor 2, and the other end 17a is a stopper 3 protruding from the end of the rack 3.
It is placed in a position where it engages with a. Note that this arm 17 has an automatic turning force in the clockwise direction in FIG.

Next, the operation of the present invention will be explained. In the illustrated state, no boost pressure is acting on the boost pressure chamber 6, and the push rod 14 is located at the rising end.

Now, when boost pressure suddenly acts on the boost pressure chamber 6, the first diaphragm 5 is displaced downward by the pressure, and presses the push rod 14 downward via the abutment member 18. This push rod 14
The second diaphragm 12 is displaced downward due to the downward pressure of the second diaphragm 12, but this displacement movement is suppressed to a slow speed by the return spring 13 and the clearance 15 that throttle the air passage. Therefore,
Even if the rack 3 suddenly tries to move in the direction of fuel increase based on the rotation of the engine, the stopper 3a contacts the other end 17a of the arm 17 and restricts the movement.
As shown in the figure, the operation of rack 3 is delayed by S time to reduce free acceleration smoke.

On the other hand, since the boost compensator 4 can be operated smoothly at low boost pressure, the starting performance at low torque is not hindered.

As described above, according to the present invention, the inside of the casing is divided by the first diaphragm into a boost pressure chamber that communicates with the intake manifold and an atmospheric pressure chamber that communicates with the atmosphere, and the second diaphragm and the , thereby providing a partitioned space, and fixing a push rod to this second diaphragm;
One end contacts the first diaphragm, and the other end passes through the casing with a clearance that communicates the space defined by the second diaphragm with the outside air and protrudes outside the casing for control. Since the push rod is engaged with an arm that restricts the movement of the rack in the fuel increasing direction, the slow control of the shaft movement speed of the push rod in response to a sudden increase in boost pressure is achieved through the return spring of the second diaphragm and the air passage formed by the clearance. It is possible to obtain a simple structure due to the squeezing action of , reducing costs and weight.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of the present invention, and FIG. 2 is a graph of the rack device based on engine speed. DESCRIPTION OF SYMBOLS 1... Fuel injection pump, 2... Governor, 3... Rack, 4... Boost compensator, 5... First diaphragm, 6... Boost pressure chamber, 7... Atmospheric pressure chamber,
8... Boost pressure introduction port, 12... Second diaphragm, 14... Push rod, 15... Clearance, 16... Engagement surface, 17... Arm, 18... Contact member, 19... Casing.

Claims (1)

[Claims] 1. In a boost compensator that controls the fuel injection amount of a fuel injection pump, the inside of the casing is divided into two chambers by a first diaphragm, one of which is a boost pressure chamber that communicates with the intake manifold, and the other is a boost pressure chamber that communicates with the intake manifold. is an atmospheric pressure chamber communicating with the atmosphere, a return spring of the first diaphragm and a second diaphragm are provided in this atmospheric pressure chamber, and a return spring of the second diaphragm is provided in a space partitioned by the second diaphragm. and a push rod is fixed to the second diaphragm, one end of which abuts the first diaphragm, and the other end communicates between the casing and the space defined by the second diaphragm and outside air. 1. A boost compensator, characterized in that the boost compensator is formed with an engaging surface that penetrates through the casing and projects out of the casing, and that engages with an arm that restricts the movement of the control rack at the other end in the fuel increasing direction.