JPH0312649B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an altitude correction device for fuel injection amount.

The full-load injection amount of a diesel engine is generally determined by the smoke emission concentration, and as the altitude increases, the full-load injection amount is reduced to prevent excessive smoke emission at high altitudes. For distribution injection pumps, an aneroid bellows or constant pressure valve (hereinafter referred to as
CPV (abbreviation)) is used to move the adjusting rod in accordance with atmospheric pressure, changing the fully open stop position of the governor tension lever.
However, in this conventional method, there is no degree of freedom in the correction amount for the full load injection amount with respect to the engine speed, and due to the structural pump characteristics of the distribution type injection pump, the correction characteristic curve shows that the injection amount becomes smaller in the higher rotation range as shown in Figure 2. The disadvantage was that there were too many. Note that A and B are conventional correction characteristics for altitudes of 1000 m and 2000 m, respectively, C is a required correction characteristic for an altitude of 1000 m, D is a correction characteristic for 1000 m altitude of the present invention, and F is a lowland full load characteristic.

An object of the present invention is to eliminate the drawbacks of the conventional devices, to provide a fuel injection system in which the full-load injection amount characteristic at high altitudes of a diesel engine is appropriately adjusted to the rotation speed, and which prevents excessive smoke emission at high altitudes. There is a large amount of altitude correction equipment available.

The fuel injection amount altitude correction device of the present invention energizes the solenoid valve when the altitude is higher than a specified standard altitude and the engine speed is higher than a specified engine speed, and the negative pressure generated by the constant pressure valve is leaked to the atmosphere.
It is constructed to achieve the above objective by reducing the degree of vacuum applied to the air (abbreviated as "") (reducing the differential pressure with atmospheric pressure).

An embodiment of the fuel injection amount altitude correction device according to the present invention will be described below with reference to FIGS. 1 and 2.

Figure 1 shows the injection amount correction system of the present invention.
CPV, 2 is BCS attached to injection pump, 3 is vacuum switch, 4 is rotary pickup, 5 is solenoid valve, 6 is ESS (hereinafter abbreviated as engine speed sensor), 7 is vacuum source, 8 is CPV output negative pressure passage 9 is Pout (negative pressure applied to BCS), 10 is a fuel injection pump, 20 is a first branch point, and 21 is a second branch point.

The inside of the CPV 1 communicates with the vacuum source 7 and is equipped with a bellows 1a and an outside air communication valve 1b.When the degree of vacuum inside the CPV 1 increases, the bellows 1a expands and the valve 1
b opens to leak the atmosphere and is maintained at a constant set negative pressure.

Vacuum switch 3 has diaphragm 3 inside.
The room divided into two by a and fitted with spring 3b is
It is communicated with the CPV 1 and maintained at a constant negative pressure, and the opposite side of the diaphragm 3a is open to the atmosphere.
A moving contact 3c is provided on the diaphragm 3a, and this contact closes when the altitude becomes high and the atmospheric pressure becomes lower than a set value (absolute value). Further, the contact point of the engine speed sensor (ESS) 6 closes when the engine speed exceeds a set rotation speed.

When the solenoid valve 5 is energized, it opens and leaks outside air into the negative pressure passage 8, causing the injection pump 1 to
Weaken the negative pressure Pout applied to 0.

The fuel injection pump 1 used here is a distribution type and comes with a boost convencator (BCS) 2, and the chamber of the BCS 2 is connected to the top by a diaphragm 11.
It is divided into two lower chambers, the upper chamber is in communication with the atmosphere, and the lower chamber is in communication with the CPV 1. When the altitude is above the specified altitude and the engine speed is above the specified engine speed, the vacuum switch 3 and ESS 6 are closed and the solenoid valve 5 is energized, reducing the negative pressure generated by the CPV. It is configured to leak to the atmosphere and weaken the degree of vacuum of the negative pressure Pout applied to the BCS2.

When the negative pressure Pout applied to the BCS 2 becomes weaker, the adjusting rod 12 rises, and the lever 14 rotates counterclockwise due to the action of its taper 13, and the lower part of the tension lever 15 moves to the left, causing the control sleeve 16 to move. Shift to the direction of fuel reduction. Note that 17 is a plunger of the injection pump.

Next, the operation of the above embodiment will be explained.

When the constant negative pressure created by the CPV 1 is introduced into the negative pressure chamber of the vacuum switch 3, the diaphragm 3a is separated and the outside of the vacuum switch 3 is released to the atmosphere. 100m in the figure), the contact point of vacuum switch 3 closes. Next, a signal is sent from the rotation pickup 4 of the injection pump 10 to the ESS 6, and when the rotation speed exceeds a specified number (3000 rpm in FIG. 2), the contacts of the ESS 6 close. In the diagram, the altitude is 1000
m or more and the engine speed becomes 3000 rpm or more, both contacts of the vacuum switch 3 and ESS 6 close, so the solenoid valve 5 is energized, the atmosphere leaks, and the negative pressure Pout applied at the BCS 2 is weakened.
As mentioned above, conventionally highlands A and B of 1000m and 2000m
However, according to the present invention, the injection amount increased as the rotation became higher, as shown by the dashed line.
At 1000m, the engine will move as shown by the broken line D.
The injection amount will be reduced at high speed rotations of 3000rpm or higher. The two-dot chain line C indicates the appropriate correction characteristic, and the point E indicates the appropriate correction characteristic.
The ESS setting rotation speed, F, is the appropriate lowland full-throttle injection amount curve. In addition, the solenoid valve 5 of the system is duty-controlled according to the engine speed, so that the leakage amount of the CPV negative pressure applied to the BCS 2 to the atmosphere is smoothly increased according to the engine speed, and the injection amount correction amount is kept constant with respect to the engine speed. It is also possible to do so.

As mentioned above, the system uses a constant negative pressure valve and a boost compensator attached to the injection pump to correct the fuel injection amount depending on the altitude, and is equipped with a vacuum switch that detects the altitude and operates, and an engine speed sensor that detects the engine rotation. When the altitude is above the specified altitude and the engine speed is above the specified engine speed, the solenoid valve is energized and the Pout led from the constant negative pressure valve is leaked to the atmosphere, reducing the vacuum level of the Pout applied to the boost compensator. Excessive smoke emission can be prevented at high altitudes and at high speeds.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the injection amount correction system of the present invention, and FIG. 2 is a diagram showing the relationship between the rotation speed and the fuel injection amount using altitude as a parameter in the conventional example and the present embodiment. 1... Constant pressure valve (CPV), 2... Boost compensator (BCS), 3... Vacuum switch,
5... Solenoid valve, 6... Engine speed sensor (EES), 8... Negative pressure passage, 10... Fuel injection pump.

Claims (1)

[Scope of Claims] 1. In a device that adjusts the maximum fuel injection amount at high altitudes using a boost compensator attached to a diaphragm-type diesel engine fuel injection pump that is controlled by a constant pressure and atmospheric pressure from a constant pressure valve, the above-mentioned A negative pressure passage connecting the constant pressure valve and the boost compensator, and a first branch point formed in the negative pressure passage are arranged to branch off and are controlled by the differential pressure between the constant pressure from the constant pressure valve and atmospheric pressure. a vacuum switch that detects the rotational speed of the engine, an engine speed sensor that detects the rotational speed of the engine, and a second branch point formed between the first branch point of the negative pressure passage and the convencator; a solenoid valve arranged between the first branch point and the second branch point and communicating the negative pressure passage with the atmosphere in response to signals from the vacuum switch and the engine speed sensor; orifices respectively arranged between the second branch point and the above-mentioned second branch point, and when the altitude is above the standard specified altitude and the specified engine speed is above, the solenoid valve is energized, and the negative pressure generated from the constant pressure valve is released to the atmosphere. A fuel injection amount altitude correction device configured to reduce the degree of vacuum leaked and applied to the boost convencator.