JPS6128027Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a fuel injection timing adjustment device for a diesel engine that appropriately adjusts the injection timing of high-pressure fuel.

Generally, diesel engine fuel injection timing adjustment devices are configured to advance the injection timing as the engine speed increases, but in order to improve engine thermal efficiency, noise, exhaust gas characteristics, etc. It is necessary to accurately adjust the injection timing. Therefore, for example, in Japanese Utility Model Publication No. 53-37136, a variable angle device is provided between the injection pump camshaft and the engine drive shaft to control the fuel injection timing based on control factors such as rotation speed, load, and temperature. A device has been proposed. However, although such devices provide accurate control, they are large and
As illustrated in the publication, there is a problem in that it is difficult to mount the engine on a tower unless it is a large engine that uses an in-line injection pump.

This idea was made in view of the above circumstances,
The purpose of the present invention is to provide a fuel injection timing adjustment device for a diesel engine with a simple configuration that can improve engine thermal efficiency, etc. by adjusting the injection timing according to engine temperature, load size, atmospheric pressure, etc. do.

Embodiments of this invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of this invention, and is an overall view including a cross section of the main parts, in which 11 is a fuel injection pump, 12 is a housing, and 13 is 1/2 of the engine crankshaft (not shown). 14 is a vane-shaped feed pump attached to the drive shaft 13; 15 is a pump chamber formed in the housing 12; when the feed pump 14 is driven, fuel is pumped from the fuel tank 16; Pressurizes the fuel passage 17.
The internal pressure of the pump chamber 15 is thereby increased as the rotational speed of the drive shaft 13, that is, the rotational speed of the engine increases.

18 is a sliding hole 19 formed in the housing 12.
A pump/distribution plunger fitted inside the
A cam disk 20 on which a cam surface 20a having a number of peaks corresponding to the number of cylinders of the engine is formed is fixed to the base end of the plunger 18, and the cam disk 20 and the drive shaft 13 are connected to a driving disk. (not shown). On the other hand, inside the housing 12,
A roller holder 21 is rotatably provided with respect to the drive shaft 13, and this roller holder 21 holds rollers 22 of the same number as the number of ridges on the cam surface 20a of the cam disk 20. The cam surface 20a is pressed by a plunger spring (not shown), and the cam disk 20 rotates on the roller 22, causing the plunger 18 to perform reciprocating motion for pumping fuel and rotational motion for dispensing fuel. It is configured to allow both to be performed at the same time. That is, during the suction stroke in which the plunger 18 descends while rotating, the high-pressure fuel in the pump chamber 15 flows from the supply hole 23 formed in the housing 12 into the plurality of vertical grooves 24 provided on the outer periphery of the tip of the plunger 18. When the plunger 18 enters the pumping stroke in which it moves upward while rotating, the tip of the plunger 18 connects the supply hole 23 and the vertical groove 2.
4 is cut off, the fuel in the plunger chamber 25 is compressed, and the fuel flows from the vertical hole 26 formed in the plunger 18 through the distribution groove 27 into the housing 12 in a number corresponding to the number of cylinders in the circumferential direction. The fuel is supplied to the formed discharge hole 27, passes through a check valve 28, and is injected into the cylinder from an injection nozzle (not shown).

A cut-off port 29 communicating with the vertical hole 26 is provided in the portion of the plunger 18 facing the pump chamber 15, and a cut-off sleeve 30 is slidably set to the cut-off port 29, and the cut-off sleeve 30 is slidably set to the cut-off port 29. When the off port 29 comes off the upper edge of the cut-off sleeve 30 and opens into the pump chamber 15, the fuel in the vertical hole 26 flows into the pump chamber 15.
A governor mechanism is connected to the cut-off sleeve 30 via a lever (not shown), and this governor mechanism controls the plunger 1 of the cut-off sleeve 30.
By adjusting the position relative to 8, the timing of the end of injection is changed and the injection amount is controlled.

On the other hand, 31 is a fuel injection timing adjusting means set in the housing 12, and as shown in FIG. The roller holder 21 is connected to the roller holder 21 via a freely pivoted lever 35.
is connected to. A feed pump 14 is located on one side of the piston 33 in the cylinder 32.
A first hydraulic chamber 36 is formed on which the suction side fuel pressure of
is installed, and a piston 3 is installed on the other side.
3 through the introduction passage 38 formed in the pump chamber 1.
A second hydraulic chamber 39 is formed on which the pressure of the fuel in 5 acts, so that depending on the pressure of the fuel,
That is, the position of the piston 33 moves according to the engine rotation speed, and the circumferential position of the roller holder 21 is determined via the lever 35, and the change in the circumferential position of the roller holder 21 causes the roller 22 to move. and the cam surface 20 of the cam disk 20 in FIG.
The contact position with a changes, and the fuel injection timing changes. In other words, the rotational speed of the drive shaft 13 increases, the pressure in the second hydraulic chamber 39 in FIG. When the differential pressure becomes larger, the piston 33 is moved upward 41 against the spring force, the roller holder 21 is rotated clockwise, and the fuel injection timing is advanced.

Furthermore, a switching valve 43 is interposed in the fuel passage 17 from the feed pump 14 to the pump chamber 15 in FIG.
Two pressure regulating valves 44, 45 are interposed in parallel, and by switching the switching valve 43, the pressure regulating valves 44, 45 are
5 is selected and activated. The pressure regulating valves 44 and 45 are the plungers 5
1, 52 and springs 46, 47, these plungers 51, 52 and springs 4
6 and 47, the fuel passage 17 and the return passage 48 are gradually opened in accordance with the pressure of the fuel in the fuel passage 17, and a part of the fuel in the fuel passage 17 passes through the return passage 48 and is transferred to the fuel passage 48. By returning the fuel to the tank 16, the pressure of the fuel in the fuel passage 17 is adjusted, and its pressure characteristics, that is, in this case, the pressure of the fuel in the fuel passage 17 relative to the rotational speed of the engine that is interlocked with the feed pump 14. The change is determined by the magnitude of the spring constant (hereinafter referred to as spring force) of the valve springs 46, 47 of each pressure regulating valve 44, 45.

By the way, if the fuel injection timing of a diesel engine is appropriately adjusted according to its operating condition, it is expected that the thermal efficiency and the like will be improved. for example,
As shown in Figure 3, during cold engine operation, the A line
During warm-up operation, if the fuel injection timing is advanced to match line B, thermal efficiency can be improved and nitrogen oxides can be reduced. So, for example,
When the spring force of the valve spring of the pressure regulating valve 44 shown in FIG. When the pressure regulating valve 44 is selected and operated by performing the switching operation, the pressure of the fuel in the fuel passage 17 is maintained relatively high, and the pressure of the fuel in the fuel passage 17 and the pump chamber 1 is maintained relatively high.
The pressure of the fuel introduced into the hydraulic chamber 39 of the fuel injection timing adjustment means 31 through the introduction passage 38 shown in FIG. Proceed along line A. Similarly, during warm-up operation when the engine temperature is high, if the switching valve 43 is operated to select the pressure regulating valve 45 having the valve spring 47 with a small spring force, the fuel injection timing will be set as indicated by the line B in Fig. 3. As such, the engine progresses at a later timing than during cold engine operation.

In addition, the switching valve 43 is operated to switch depending on the operating state of the engine other than the above-mentioned temperature, for example, depending on the magnitude of the load, so that when the load is high, the fuel injection timing is advanced compared to when the load is low, or when the air density is low. When the fuel injection timing is advanced at high altitudes compared to low altitudes, thermal efficiency, noise, and exhaust gas characteristics are improved in the same way as explained regarding the engine temperature in FIG. 3.

As explained above, according to this invention, it is possible to appropriately adjust the fuel injection timing according to the operating condition of the diesel engine with a simple configuration that only includes a switching valve and a plurality of pressure regulating valves.
This has high practical value as it improves the thermal efficiency of diesel engines, reduces noise, and reduces nitrogen oxides in exhaust gas.

[Brief explanation of the drawing]

FIG. 1 is an overall view showing an embodiment of this invention, FIG. 2 is a sectional view taken along the line 2--2 in FIG. 1, and FIG. 3 is a characteristic diagram showing an example of fuel injection timing. 14...Feed pump, 17...Fuel passage,
31...Fuel injection timing adjustment means, 43...Switching valve, 44, 45...Pressure regulating valve, 46, 47...Spring, 48...Return passage, 51, 52...Plunger.

Claims (1)

[Scope of utility model registration request] A switching valve is interposed in the fuel passage that connects the feed pump that boosts the pressure of the fuel and the fuel injection timing adjusting means that adjusts the fuel injection timing according to the pressure of the boosted fuel. A plurality of pressure regulating valves are arranged in parallel in the fuel passage, and these pressure regulating valves are provided with a plunger and a spring that gradually open the fuel passage and a return passage for returning the fuel to the fuel tank according to the pressure of the fuel, and , the spring constant of the above spring is different for each pressure regulating valve,
By appropriately switching the switching valves according to the operating condition of the engine, one of the pressure regulating valves is selected and operated, and the pressure of the fuel guided to the fuel injection timing adjusting means through the fuel passage is adjusted. A diesel engine fuel injection timing adjustment device characterized by adjusting the fuel injection timing.