JPS6332916Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel injection device for a diesel engine.

Generally speaking, diesel engine fuel injection systems are designed to delay the fuel injection timing under low and medium loads to reduce NOx and reduce noise, while returning to the normal fuel injection timing during high loads to ensure sufficient fuel injection timing. It has been proposed to install a device, such as a road timer, that adjusts the fuel injection timing according to changes in load so as to produce a suitable output.

However, in a diesel engine that uses such a device, even when the engine is cold, the fuel injection timing is delayed if the load is low or medium, so the combustion state may be affected when the engine is cold. The problem is that it gets worse and half-misfires occur.

Therefore, as a conventional method to eliminate such problems, for example, the timer piston of the timer that adjusts the fuel injection timing, or the roller holder linked to the timer piston, is coated with wax pellets or the like when the engine is cold. Something that moves it to the forward side has been proposed.

However, this method can only correct the fuel injection timing at low engine speeds, so the load timer activates at high engine speeds, delaying the fuel injection timing and preventing proper combustion in the high engine speed range. There is a drawback.

In view of these points, the present invention includes a cam means that reciprocates a plunger that pumps fuel, and the cam means is actuated by hydraulic pressure in the pump chamber corresponding to the engine speed, and the fuel injection timing is adjusted according to the engine speed. a timer with a timer piston that
The relief passage, which is formed in the governor shaft and reduces the hydraulic pressure in the pump chamber that acts on the timer piston, and the governor sleeve fitted into the governor shaft move in response to the engine load, thereby reducing the engine load. Temperature detection means for detecting the temperature state of the engine, comprising a load timer that closes the relief passage when the engine load is high and opens the relief passage when the engine load is low to delay the fuel injection timing at low loads compared to high loads. A fuel injection system for a diesel engine that eliminates the above-mentioned conventional drawbacks by reducing the oil pressure lowering function of the load timer using a reducing means when the temperature detecting means confirms that the engine is cold. The main purpose is to provide equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to the drawings.

In the distribution type fuel injection pump 1 shown in FIGS. 1 and 2, 2 is a housing, 3 is a drive shaft that is driven at 1/2 the rotation speed of the engine crankshaft (not shown), and 4 is installed in the housing 2. The pump chamber 5 formed is a suction passage that connects the pump chamber 4 to a fuel tank (not shown). 6 is a vane type feed pump interposed in the middle of the suction passage 5, and is driven by the drive shaft 3. By driving the feed pump 6, fuel from the fuel tank is forced into the pump chamber 4 through the suction passage 5, and the internal pressure in the pump chamber 4 is increased to increase the rotational speed of the drive shaft 3, that is, the engine rotational speed. It is configured to increase accordingly.

A pump/distribution plunger 7 is slidably inserted into a sliding hole 8 formed in the housing 2. A cam disk 9 on which a cam surface 9a having a number of ridges corresponding to the number of cylinders of the engine is formed is fixed to the end of the plunger 7, and the drive shaft 3 is connected to a driving disk (not shown) on the cam disk 9. The two are connected in the rotational direction via

A roller holder 10 is rotatably provided in the housing 2 concentrically with the drive shaft 3, and rotatably has the same number of rollers 11 as the number of ridges on the cam surface 9a of the cam disk 9 (that is, the number corresponding to the number of cylinders). is maintained. This roller 11 has
The cam surface 9a of the cam disk 9 is pressed by a plunger spring (not shown), and the roller 1
When the cam disk 9 rotates on the cam disk 1, the plunger 7 is configured to simultaneously perform a reciprocating motion for sucking and pumping fuel and a rotational motion for distributing fuel.

Therefore, when the plunger 7 is in the suction process (downward movement in FIG. 1), the fuel in the pump chamber 4 flows from the supply passage 12 formed in the housing 2 to the plurality of channels provided on the outer peripheral surface of the head of the plunger 7. vertical groove 13
(four in this example) through one of the plunger chambers 29
supplied to Furthermore, when the plunger 7 moves to the pressure feeding process (increasing movement in FIG. 1), the supply passage 1
2 and the vertical groove 13 is cut off, the fuel in the plunger chamber 29 is compressed, and the fuel passes from the vertical hole 14 formed in the plunger 7 through the distribution horizontal hole 15 into the housing 2 in the circumferential direction to the number of cylinders. The fuel is supplied to one of the discharge passages 17 having check valves 16 formed in a number corresponding to the number of the fuel, and is injected into the cylinder from an injection nozzle (not shown).

18 is a cut-off sleeve, and a cut-off port 19 communicating with the vertical hole 14 of the plunger 7 is provided in the portion of the plunger 7 that protrudes toward the pump chamber 4 side.
It is slidably fitted on the outside so that it can be opened and closed. When the cut-off port 19 is removed from the upper edge of the cut-off sleeve 18 and opens into the pump chamber 4,
The fuel flows out into the pump chamber 4 and stops being discharged to the discharge passage 17, thus completing the injection.

A flyweight 20 is provided in a flyweight holder 30 that is integrally fixed to the gear 21. This flyweight holder 30 is attached to the governor shaft 22 and driven by a drive shaft 3 to which a gear (not shown) that meshes with the gear 21 is fixed. Also, fly weight 2
0 movement is the small diameter portion 22a of the governor shaft 22.
The signal is transmitted to the governor sleeve 23, which is slidably fitted on the outer surface of the governor sleeve 23. A relief port 24 is opened in the governor sleeve 23, and when the governor sleeve 23 is in a low/medium load position where the amount of fuel injection is not large, the relief port 24 is connected to the governor shaft 22.
The pump chamber 4 is communicated with the relief passage 27 of the housing 2 through the relief port 24, the horizontal hole 25, and the vertical hole 26 of the governor shaft 22, thereby allowing the hydraulic pressure in the pump chamber 4 to be communicated with the relief passage 27 of the housing 2. lower. This relief passage 27 is connected to the suction side (low pressure side) of the feed pump 6 via a solenoid valve 28. 31 is when the engine is cold;
For example, it is a cold switch that opens when the engine coolant temperature is 80° C. or lower, and one end is electrically connected to a battery (not shown) and the other end is electrically connected to a solenoid valve 28. Therefore, when the engine is warm, the cold engine switch 31 is closed and the solenoid valve 28 is energized.
The relief passage 27 is opened and the governor sleeve 23 is
Due to the movement of pump chamber 4 at low and medium loads
The fuel injection timing is adjusted to the delayed side by the movement of a timer piston 46, which will be described later. On the other hand, when the engine is cold, the cold engine switch 31 is opened and the solenoid valve 28 is not excited and closes the relief passage 27.
Even during low and medium load conditions when the relief port 24 of the governor shaft 22 is communicated with the horizontal hole 25 of the governor shaft 22, the oil pressure in the pump chamber 4 does not drop below the oil pressure corresponding to the rotation speed of the feed pump 6.
Fuel injection timing is not delayed when the load is high.

32 is a governor lever assembly, and a tension lever 33 is mounted on the collector lever (not shown).
One end of the start lever 34 is pivotally supported by a pivot pin 35, and one end of the start lever 34 is supported by a pivot pin 35.
An engagement groove 1 of the cut-off sleeve 18 is provided at one end of the cut-off sleeve 18.
A ball head pin 37 is attached which engages 8a. 38 is a start spring 38 (plate spring) fixed to the other end of the start lever 34
It is interposed between the levers 33 and 34.

Reference numeral 39 denotes a governor spring, one end of which is attached to the tension lever 33 via a support pin 40, and the other end of which is attached to a rotation shaft 42 of a control lever 41 linked to an accelerator pedal (not shown).
is connected to via a shackle 43. The control rotation speed is determined by the elastic force of the governor spring 39.

A timer 44 controls the fuel injection timing, and has a timer piston 46 that slides within a cylinder 45 formed within the housing 2. This timer piston 46 is connected to the roller holder 10 via a lever 48 that is swingable about a fixed shaft 47. Also, a spring 49 is provided on one side of the cylinder 45, sandwiching the timer piston 46.
A first hydraulic chamber 50 is formed in which the fuel pressure on the suction side of the feed pump 6 acts, and a hydraulic passage 51 provided in the timer piston 46 is formed on the other side.
A second hydraulic chamber 52 is formed through which the fuel pressure of the pump chamber 4 acts. The position of the timer piston 46 is controlled by the differential pressure between the first hydraulic chamber 50 and the second hydraulic chamber 52, that is, the fuel pressure according to the engine speed, and the elastic force of the spring 49, that is, the lever 48. Since the inner circumferential position of the roller holder 10 is determined and the contact position between the roller 11 and the cam surface 9a of the cam disk 9 changes, the circumferential phase of the drive shaft 3 and the contact position, that is, the operating position of the plunger 7, are changed. A relative change occurs, and the fuel injection timing advances as the oil pressure of the feed pump increases, that is, the engine speed increases.

With the above configuration, when the engine is warm, the cold switch 31 closes and the solenoid valve 28 opens, so the relief passage 27 is opened to the fuel tank (low pressure side). Therefore, when the engine load is small, the tension of the governor spring 39 is weak, and the fly weight 20 causes the governor sleeve 23 to move upward (in FIG. 1), thereby causing the horizontal hole 25 of the governor shaft 22 to , and the relief port 24 of the governor sleeve 23, thereby communicating the pump chamber 4 with the fuel tank via the relief passage 27, so that the pressure within the pump chamber 4 is released and reduced. Along with this, the pressure in the second hydraulic chamber 52 of the timer 44 also decreases, so that the timer piston 46 is moved by the elastic force of the spring 49.
being pulled back to the lag side.

When the engine load exceeds the set value and the fuel injection amount increases, the governor sleeve 23 moves downward (in FIG. 1), and the horizontal hole 25 of the governor shaft 22 and the relief port 24 of the governor sleeve 23 are connected. They are separated, communication between the pump chamber 4 and the fuel tank is cut off, and the pressure inside the pump chamber 4 increases. Along with this, the pressure in the second hydraulic chamber 52 of the timer 44 also increases, so the timer piston 46 moves toward the forward side against the elastic force of the spring 49 and returns to its original state.

On the other hand, when the engine is cold, the cold engine switch 31
opens, so the solenoid valve 28 closes without being energized.
Close the relief passage 27. As a result, the pressure inside the pump chamber 4 does not decrease, and the fuel injection timing is controlled without delay even during low and medium loads as in the case of high loads. Therefore, the combustion state is improved, half-misfire can be prevented, and vibration noise and HC can be reduced.

FIGS. 3 and 4 show the above operation in terms of the relationship between engine load or engine speed and fuel injection timing.

First, Figure 3 shows the relationship between load and injection timing when the engine speed is constant, and the solid line A
is the change when the engine is warm, and the dashed line B is
This shows changes when the engine is cold. Therefore, it can be seen that when the engine is cold, the fuel injection timing does not change due to changes in load.

Further, in FIG. 4, a solid line C shows changes in a warm engine state at a high load and in a cold engine state, and a solid line D shows a change in a warm engine state at a low load and a medium load. Therefore, it can be seen that when the engine is cold, as the engine rotational speed increases, it increases linearly and proportionally, similar to when the engine is warm and under high load.

In the above embodiment, the hydraulic pressure in the pump chamber is reduced according to the engine cold load and the operation of the load timer that controls the injection timing is completely stopped.
It only needs to reduce the retardation function of the hydraulic pressure control means when the engine is cold compared to when the engine is warm. It may also be something that reduces it. Alternatively, the passage area of the relief passage may be made variable depending on the temperature state of the engine, so that the passage area of the relief passage increases as the temperature rises.

In addition, as a means of detecting the temperature state of the engine, the cooling water temperature is detected, but other signals such as a timer from the engine combustion chamber temperature start to a set time, fuel temperature in the pump chamber, etc. You can also do this.

As described above, the present invention is configured such that the operating function of the load timer, which delays the fuel injection timing by reducing the hydraulic pressure acting on the injection timing adjusting means when the engine load is small, is reduced when the engine is cold. When the engine is cold, the fuel injection timing is advanced even in the high rotation range, preventing half-misfires and reducing vibration noise and HC, which is an excellent practical effect. Furthermore, the present invention has the advantage that the above-mentioned effects can be achieved with a simple structure in which a solenoid valve that closes the relief passage of an existing load timer is provided to close the passage when the load timer is cold.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, in which Fig. 1 is a longitudinal sectional view of a fuel injection device for a diesel engine, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 shows engine load and fuel injection. A diagram showing the relationship with time,
FIG. 4 is a diagram showing the relationship between engine speed and fuel injection timing. 1...Fuel injection pump, 2...Housing, 3
...Driveshaft, 4...Pump chamber, 5...
Suction passage, 6... Feed pump, 7... Pump/distribution plunger, 8... Sliding hole, 9... Cam disc, 9a... Cam surface, 10... Roller holder, 11... Roller, 12... Supply passage, 13...
... Vertical groove, 14 ... Vertical hole, 15 ... Distribution horizontal hole, 16
...Check valve, 17...Discharge passage, 18...Cut-off sleeve, 19...Cut-off port, 20
... Fly weight, 21 ... Gear, 22 ... Governor shaft, 22a ... Small diameter section, 23 ... Governor sleeve, 24 ... Relief port, 25 ...
Horizontal hole, 26... Vertical hole, 27... Relief passage, 2
8...Solenoid valve, 29...Plunger chamber, 30...
Fly weight holder, 31...Cold machine switch,
32...Governor lever assembly, 33...Tension lever, 34...Start lever, 35
...Pivot pin, 18a...Engagement groove, 37...
Ball head pin, 38... Start spring, 39... Governor spring, 40... Support pin, 41... Control lever, 42... Rotating shaft, 43... Shackle, 44... Timer, 4
5...Cylinder, 46...Timer piston, 4
7... Fixed shaft, 48... Lever, 49... Spring, 50... First hydraulic chamber, 51... Hydraulic passage,
52...Second hydraulic chamber.

Claims (1)

[Scope of utility model registration request] A timer comprising: a cam means for reciprocating a plunger that pumps fuel; and a timer piston that operates the cam means with hydraulic pressure in the pump chamber corresponding to the engine speed and adjusts the fuel injection timing according to the engine speed. , a relief passage formed in the governor shaft that reduces the hydraulic pressure in the pump chamber acting on the timer piston, and a governor sleeve fitted into the governor shaft that moves in response to the engine load to close the relief passage when the engine load is large. , a load timer that opens a relief passage when the engine load is low and delays the fuel injection timing at low loads compared to high loads, wherein a temperature detection means is provided for detecting the temperature state of the engine, and the temperature detection means is provided. A fuel injection device for a diesel engine, characterized in that the fuel injection device for a diesel engine is linked to a reduction means for controlling the relief passage in a closing direction when the engine is cold.