JPS63612B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing adjustment device for an internal combustion engine.

Conventional fuel injection pumps are provided with a fuel injection timing adjustment device that operates in response to, for example, pressure within the pump housing, and the fuel injection timing is adjusted in accordance with the positional displacement of a timer piston of this device. It is configured as follows. by the way,
The pressure within the housing is provided by a vane pump driven by the rotating shaft of the fuel injection pump, and the pressure is regulated by a pressure regulating valve so that it changes in proportion to the engine speed. Therefore, the fuel injection timing is uniquely determined by the rotational speed of the engine, and it is not possible to adjust the injection timing due to changes in the magnitude of the load, for example. For this reason, as the load changes, the fuel injection timing may advance or lag too much relative to the optimum timing, resulting in inadequate combustion, noise generation, or insufficient output. are doing. In particular, when the engine accelerates, it also has the drawback of generating smoke in the low speed rotation range and generating harmful gases in the medium to high speed rotation range.

Furthermore, when starting an internal combustion engine, it is necessary to advance the fuel injection timing in order to ensure a stable start. In this region, a starting advance angle device devised to advance the fuel injection timing is installed. This fuel injection timing adjusting device with a starting advance angle device has a timer piston and an auxiliary piston. are provided in the cylinder so that they face each other and are biased by a spring so as to press against each other, and in the first cylinder space formed by these two pressure receiving surfaces, there is a pressure inside the housing that changes in relation to the engine speed. When pressure is introduced and this pressure is below a predetermined value, the timer piston is moved to follow the pressure response operation of the auxiliary piston, and when this pressure is above a predetermined value, the timer piston is moved in accordance with this pressure. It is configured to allow Such a configuration requires two pistons, making the device complicated and expensive. In addition, as shown in FIG.
is accelerated, but after that, the idle speed Ni
The advance angle θ is delayed as it approaches . Therefore, although there is no problem immediately after starting, the rotation of the internal combustion engine becomes unstable as it approaches the idle speed Ni, and there is a drawback that a stable starting operation cannot be performed. In other words, it is generally desirable for internal combustion engines to advance the fuel injection timing until complete explosion after startup, but conventional fuel injection timing adjustment devices with a startup advance device can advance the timing only immediately after startup; Therefore, stable starting could not be performed. This tendency is particularly noticeable when it is difficult to start the internal combustion engine, such as during cold and cold seasons, and is the cause of many accidents such as the internal combustion engine stopping after starting.

Furthermore, the optimal fuel injection timing at startup is
Although it depends on environmental conditions such as the temperature of the internal combustion engine, conventional timing adjustment only takes into account the rotational speed of the internal combustion engine, so it has the disadvantage that it is not always possible to perform optimal timing adjustment. ing.

Therefore, an object of the present invention is to provide a fuel injection timing for an internal combustion engine with a simple configuration, which can accurately provide the necessary starting advance angle at the time of starting the internal combustion engine, and can improve the startability of the engine. The object of the present invention is to provide a regulating device.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 2 schematically shows an embodiment of an internal combustion engine device 1 equipped with a fuel injection timing adjustment device according to the present invention. The internal combustion engine device 1 includes a diesel engine 2 and a distribution type fuel injection pump 3. The fuel injection pump 3 injects fuel in a fuel tank 4 through a pipe 5 from an injection nozzle 6 to the diesel engine 2.
Injected into the tank. The timing of this fuel injection is adjusted by a fuel injection timing adjustment device according to the present invention, which includes a timer 7. To control the timer 7, the device 1 has a control unit 8,
The control unit 8 includes a rotation speed signal S ₁ from a rotation speed detector 9 and a water temperature sensor 1 that detects the temperature of the cooling water.
0 from the water temperature signal S ₂ , a top dead center timing signal S ₃ from the top dead center timing detector 11 that detects the top dead center timing of the engine, and a top dead center timing signal S 3 from the lift sensor 12 that detects the needle valve lift timing of the injection nozzle 6. A lift timing signal S ₄ and a load signal S ₅ from a load detector 13 attached to the fuel injection pump 3 are input, and two control signals S ₆ and S ₇ generated based on these input signals are sent to the timer 7. is applied to.

Referring to FIG.
4, and the piston 1 housed within the cylinder 14.
5, and resilient springs 18, 19 are provided in the cylinder chambers 16, 17 formed at both ends of the piston 15.
is stored. A window 20 is formed in the middle of the peripheral wall of the cylinder 14, and a portion of the piston 15 can be seen through this window 20. In order to introduce pressurized fuel in the main body of the fuel injection pump 3 in which the roller holder 26 is disposed into the cylinder chambers 16 and 17 through the window 20, the piston 15 is provided with a first Two orifices 21 and 22 are formed corresponding to the passage means and the second passage means. The orifice 21 has one end opened into the cylinder chamber 16 and the other end opened into the exposed surface 15a of the piston 15 peeking through the window 20. Pressurized fuel is introduced into the cylinder chamber 16 . The other orifice 22 has a similar configuration and introduces the pressurized fuel in the fuel injection pump 3 into the cylinder chamber 17. In the illustrated embodiment, the piston 15 has recesses 23 and 24 on both end surfaces.
are formed, and within these recesses are springs 18, respectively.
19 is housed, thereby causing the springs 18,1
9 can be stably provided in the cylinder chambers 16 and 17. The piston 15 has
One end of the rod 25 is connected via a universal joint through the window 20, and the other end of the rod 25 is connected to the roller holder 2.
It is fixed to the drive shaft 27 of No. 6. Therefore, when the piston 15 is moved in the axial direction within the cylinder 14 as described later, the roller holder 26 is displaced from the reference position according to the position of the piston 15, and the timer 7 controls the fuel injection advance angle. Adjustments can be made.

Note that shoulders 28 and 29 are formed near both ends of the inner circumferential wall of the cylinder 14 as stoppers for the piston 15, and limit the displacement range of the piston 15.

In order to allow the cylinder chambers 16 and 17 to communicate with the low pressure side of the fuel, openings 30 and 31 are formed on both end faces of the cylinder 14, and these openings 30 and 31 are connected to pipes, respectively. It is connected to one end opening of each electromagnetic valve 34, 35 via 32, 33. The openings at the other ends of the electromagnetic valves 34 and 35 are opened into the fuel tank 4 through a pipe 50.

These solenoid valves 34 and 35 are driven by control signals S ₆ and S ₇ from the control unit 8 shown in FIG. 2, respectively. The control signals S ₆ and S ₇ are pulse signals whose duty ratios are controlled, and the solenoid valves 34 and 35 are opened only when the applied signals are at a high level. Therefore, the average opening degree of each electromagnetic valve is controlled by changing the duty ratio of the control signals S ₆ and S ₇ . As a result, the timer 7 indicates that when the engine is stopped, the pressures in the cylinder chambers 16 and 17 are equalized by the orifices 21 and 22.
The piston 15 is positioned at a position where the spring forces of the springs 18 and 19 are balanced. Piston 1 at this time
The position of No. 5 is adjusted to give the optimum advance angle at the time of starting. Therefore, the position of the cylinder chamber No.
When the pressure in the cylinder chamber 15 is equal to the pressure in the cylinder chamber 15, the timer 7 gives the required starting advance angle value. After startup, when the average opening of the solenoid valve is adjusted, the pressure in the cylinder chamber changes depending on the ratio between the opening size of the orifice and the average opening of the solenoid valve, and the position of the piston 15 changes to the internal pressure of the cylinder chambers 16 and 17. It also changes depending on the situation. That is, by changing the duty ratio of the control signals S ₆ and S ₇ , the position of the piston 15 can be controlled to an arbitrary position.

FIG. 4 shows a block diagram of the control unit 8 for controlling these electromagnetic valves 34, 35. The control unit 8 receives a rotational speed signal S ₁ ,
A target advance angle signal that responds to the water temperature signal S ₂ and load signal S ₅ and indicates the target value of the fuel injection timing (advance value) at that time.
It has an arithmetic circuit 36 that calculates and outputs _D1 .
When the engine temperature is below a predetermined value, the calculation circuit 36 calculates the optimum starting advance angle value θ _a of the fuel supplied to the diesel engine based on the water temperature signal S ₂ . This advance angle value is information that indicates how far from the top dead center position fuel injection should start, based on the top dead center position of the diesel engine, and is the target advance angle signal.
D ₁ is applied to one input of the error amplification circuit 37. Rotation speed signal S ₁ , top dead center timing signal S ₃
The lift timing signal _S4 is input to the advance angle detection circuit 38 which detects the actual fuel injection advance value in the internal combustion engine device 1, and outputs an actual advance angle signal _D2 indicating the actual advance value. The actual advance angle signal D ₂ is applied to the other input of the error dewidth circuit 37, and the error amplification circuit 37 outputs an error signal D ₃ corresponding to the level difference between both signals D ₁ and D ₂ . The error signal D ₃ is a signal indicating the magnitude of the difference between the target lead angle value calculated by the calculation circuit 36 and the actual lead angle value, and is input to the duty ratio calculation circuit 39, and is input to the control signal S ₆ , S ₇
A command signal _D4 is generated that determines the duty ratio of the pulse generators 40 and 41 that generate the .

The level T _a of this command signal D ₄ and each control signal S ₆ ,
The relationship between S ₇ and the duty ratios K ₁ and K ₂ is as shown in FIG. When the target lead angle value θ _p is set and the actual lead angle value θ is advanced, T _a changes in the negative direction, and only the duty ratio of the output of the pulse generator 41 is changed according to the magnitude of |T _a |. This makes it possible to lower the pressure in the cylinder chamber 17 and delay the injection timing. On the other hand, if the actual lead angle value θ lags behind the target lead angle value θ _p , T _a changes in the positive direction, and only the duty ratio of the output of the pulse generator 40 is changed to the magnitude of T _a . Therefore, the pressure in the cylinder chamber 16 can be lowered and the injection timing can be advanced.

Therefore, during starting operation, the optimal starting target advance angle value θ _a (see FIG. 6) at the current temperature T [°C] calculated by the calculation circuit 36 and the advance angle detection circuit 3
The difference between the lead angle value θ and the actual advance value θ outputted by 8 is determined in the error amplification circuit 37, and the duty ratio of the control signal S ₆ or S ₇ is controlled based on this result. Changes in the duty ratio are fed back to the input side of the control unit 8 as changes in the level of the actual advance angle signal _D2 , and the duty ratio is determined so that θ _a =θ. Therefore, during the starting period, the starting advance angle can always be maintained at an optimal value commensurate with the temperature at that time.

When the temperature of the engine reaches a predetermined value, stable starting operation is already being performed, and next, the optimum target load advance value according to the engine load, rotation speed, and engine temperature is calculated in the calculation circuit 36. Ru. Which type of target advance angle value is calculated in the calculation circuit 36 is determined by the level of the water temperature signal _S2 , and if the water temperature signal _S2 indicates a temperature below a predetermined value, the target start angle value is calculated. When the water temperature signal _S2 indicates a temperature equal to or higher than a predetermined value, a target load advance angle value is calculated. The control operation by which the control unit 8 sets the advance angle value determined by the timer piston 7 to the target load advance angle value is the same as the operation at the time of start-up described above, so a detailed explanation will be omitted. As a result, the advance angle value θ changes as shown in FIG. 7 as the rotational speed N changes. here,
The dotted line indicates that the advance angle value changes when the load, water temperature, etc. change.

As described above, the present internal combustion engine device 1 maintains a predetermined fuel injection timing in accordance with starting environmental conditions (for example, temperature conditions), regardless of the rotation speed of the diesel engine, when the engine temperature is below a predetermined value. Therefore, the required starting advance angle value can be maintained until complete explosion. Therefore, it is possible to improve the starting characteristics particularly in cold seasons.
Furthermore, when the engine temperature is above a predetermined value, the fuel injection timing is not determined solely by the rotation speed, but can also be determined by taking into account the engine temperature and load size, so it is always optimal. It provides a comfortable combustion state, prevents noise and smoke generation, and allows for highly efficient operation.

In addition, this device directly detects the injection timing using the lift timing of the needle valve of the injection nozzle, so the configuration is simple and the actual fuel injection start timing can be accurately detected. Extremely precise control can be performed.

In the above embodiment, temperature and load are the control factors among the external environmental conditions, but the present invention is not limited to limiting the control factors to only temperature and load. Additional factors may also be considered.

According to the present invention, as described above, with a simple configuration having only one piston, it is possible to naturally obtain a starting advance angle value that allows optimum starting according to arbitrary external environmental conditions when the engine is stopped. In addition, compared to systems that use the fuel pressure generated by the increase in engine speed to obtain the starting advance angle by controlling a solenoid valve, it has the advantage of more accurate advance angle control and improved starting performance. .

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram of a conventional timer, FIG. 2 is a schematic diagram of an embodiment of the present invention, FIG. 3 is an enlarged partial sectional view of the main part of the device shown in FIG. 1, and FIG. Figure 2 is a block diagram of the electrical system of the device, Figure 5 is a characteristic diagram showing the relationship between the command signal and the duty ratio of each control signal, Figure 6 is a characteristic diagram of the optimum starting target advance angle, and Figure 7 is a characteristic diagram showing the relationship between the command signal and the duty ratio of each control signal.
This figure is a characteristic diagram showing the control characteristics of the device shown in FIG. 1. 1... Internal combustion engine device, 2... Diesel engine,
3... Fuel injection pump, 7... Timer, 8... Control unit, 14... Cylinder, 15... Piston, 16, 17... Cylinder chamber, 18, 19...
Bomb spring, 21, 22... Orifice, 26...
Roller holder, 34, 35... Solenoid valve, 36...
Arithmetic circuit, S ₁ ... rotation speed signal, S ₂ ... water temperature signal,
_S3 ...Top dead center timing signal, _S4 ...Lift timing signal, _S5 ...Load signal, _S6 , _S7 ...Control signal, _D1 ...Target advance angle signal, _D2 ...Actual advance corner signal,
_D3 ...error signal, _D4 ...command signal.

Claims (1)

[Claims] 1 a piston that drives a roller holder, a cylinder that displaceably accommodates the piston, a first cylinder chamber and a second cylinder chamber that are formed within the cylinder on both sides of the piston, and the first cylinder chamber. In order to communicate the cylinder chamber and the second cylinder chamber with the low pressure side, a first low pressure side open passage and a second low pressure side open passage are provided at the end of the cylinder, respectively, and the first low pressure side open passage is provided at the end of the cylinder. A first spring and a second spring disposed in the cylinder chamber and the second cylinder chamber, and pressurized fuel in the chamber in which the roller holder is disposed are supplied to the first cylinder chamber and the second cylinder chamber. a first passage means and a second passage means formed by the piston for introducing the piston, and a first low pressure side open passage and for adjusting the pressure in the first cylinder chamber and the second cylinder chamber, respectively. a first solenoid valve and a second solenoid valve provided in the second low pressure side open passage; a load;
control means for controlling the first electromagnetic valve and the second electromagnetic valve to obtain a predetermined target advance angle calculated in accordance with parameters indicating the state of the internal combustion engine such as rotation speed and water temperature; A fuel injection timing adjustment device for an internal combustion engine, which provides a predetermined starting advance angle when the pressure in the first cylinder chamber is equal to the pressure in the second cylinder chamber.