JPS6261773B2 - - 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 controlled 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 area, a start-up advance device designed to advance the fuel injection timing is installed. This fuel injection timing adjustment device with a start advance device has a timer piston and an auxiliary piston, and the pressure receiving surfaces of these two pistons face each other and are biased by a spring so as to press against each other inside the cylinder. The pressure inside the housing, which changes in relation to the engine speed, is introduced into the first cylinder space formed by these two pressure receiving surfaces, and when this pressure is below a predetermined value, the timer piston is assisted. The timer piston is configured to move in accordance with the pressure-responsive operation of the piston, and when this pressure is equal to or higher than a predetermined value, the timer piston is made to respond in accordance with this pressure. Such a configuration requires two pistons, which makes the device complicated and expensive, and as shown in FIG.
The fuel injection timing θ is advanced in a region where the rotational speed is extremely low immediately after starting, but thereafter the advance angle θ is delayed as the engine speed approaches the idle rotational speed Ni. 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 after startup until complete explosion;
The conventional fuel injection timing adjusting device with a starting advance angle device can advance the timing only immediately after starting, and as a result, stable starting cannot be achieved. This tendency is particularly noticeable when starting the internal combustion engine is difficult, such as during a cold period, 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, it is an object of the present invention to make it possible to perform advance angle adjustment in accordance with required injection advance angle characteristics without complicating the configuration, particularly in the vicinity of the idle rotation speed of an internal combustion engine and in the rotation speed region below it. An object of the present invention is to provide a fuel injection timing adjustment device for an internal combustion engine.

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

FIG. 2 schematically shows an internal combustion engine device 1 equipped with a fuel injection timing adjustment device according to the invention. The internal combustion engine device 1 includes a diesel engine 2 and a fuel injection pump 3, and the fuel injection pump 3 injects fuel in a fuel tank 4 through a pipe 5 from an injection nozzle 6 into the diesel engine 2. The timing of this fuel injection is adjusted by a fuel injection timing adjustment device according to the present invention, which comprises a timer 7 and a control unit 8 for controlling the timer 7. The control unit 8 includes a rotation speed detector 9 for detecting the rotation speed of the diesel engine 2.
A rotation speed signal S ₁ from the engine, a water temperature signal S ₂ from the water temperature sensor 10 that detects the temperature of the cooling water, and a top dead center timing detector 11 that detects the top dead center timing of the engine.
the top dead center timing signal S ₃ from the fuel injection pump 3, the lift timing signal S ₄ from the lift sensor 12 that detects the needle valve lift timing of the injection nozzle 6, and the fuel injection pump 3.
The load signal S ₅ from the load detector 13 attached to
are input, and a control signal _S6 generated based on these input signals is applied to the timer 7.

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.
are stored respectively. 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. Recesses 21 and 22 are formed on both end surfaces of the piston 15, and a portion of the springs 18 and 19 are accommodated in these recesses, respectively, so that the springs 18 and 19 can be stably installed in the cylinder chambers 16 and 17. It is becoming possible to do this. The piston 15 has a window 20
One end of the rod 23 is connected via a universal joint, and the other end of the rod 23 is fixed to a roller holder 24. Therefore, as described below, the piston 15
The advance angle can be adjusted by displacing the roller holder 24 from the reference position according to the movement in the axial direction within the cylinder 14.

Note that shoulders 26 and 27 are formed near both ends of the inner circumferential wall of the cylinder 14 as stoppers for the piston 15, and limit the maximum displacement of the piston 15.

The cylinder 14 is provided with two openings for each cylinder chamber, and one of the openings 28 and 29 has passages 32 and 33 provided with throttles 30 and 31, respectively.
Pressurized fuel is supplied via. The other opening 34 provided on the cylinder chamber 16 side is open to the atmosphere via a passage 36 provided with a throttle 35 in the middle, while the other opening 37 provided on the cylinder chamber 17 side opens a solenoid valve 38. It is open to the atmosphere through. This solenoid valve 38 is driven by a control signal _S6 from the control unit 8 shown in FIG. The control signal S ₆ is a pulse signal whose duty ratio is controlled, and the solenoid valve 38 is opened when the control signal S ₆ is at a high level, and the cylinder chamber 17 is communicated with the atmosphere. On the other hand, in the cylinder chamber 16, pressurized fuel is constantly supplied through the throttle 30, and at the same time, the pressure inside the cylinder chamber 16 is released through the throttle 35. When the engine is stopped, the pressure in the cylinder chambers 16 and 17 of the timer 7 becomes atmospheric pressure, and the piston 15 is positioned at a position where the spring forces of the springs 18 and 19 are balanced. The position of the piston 15 at this time is adjusted to give the optimum advance angle at the time of starting, but the position of the piston 15 at this time is
The piston 15 is set to a position other than both ends of its movable range within the cylinder 14.

FIG. 4 shows a characteristic diagram of this timer 7. When the rotation speed N is zero, the piston position
is the position X ₁ that provides the optimum advance angle at startup. When the solenoid valve 38 is fully closed and N is increased, the pressure on the cylinder chamber 17 side increases in proportion to the increase in N, and the piston 15 moves to the left in FIG. 3 to further advance the injection timing. Once the piston 15 comes into contact with the shoulder 26, the position X remains constant regardless of the increase in N. This characteristic is indicated by the symbol A in FIG. On the other hand, when the solenoid valve 38 is fully open, the pressure in the cylinder chamber 16 increases rapidly as N increases, so the injection timing is delayed once, and when the piston 15 moves until it comes into contact with the shoulder 27, it becomes idle. It is maintained at this position within a predetermined rotational speed range around the rotational speed Ni. As N further increases, the pressure in the cylinder chamber 17 is greater than the pressure in the cylinder chamber 16 and increases further, overcoming the pressure in the cylinder chamber 16 and moving the piston 15 to the left. This characteristic is indicated by the symbol B in FIG.

Therefore, as can be seen from the above explanation, the solenoid valve 38
By controlling the opening degree of the piston, it is possible to control the piston position, that is, adjust the injection timing, within the range surrounded by characteristics A and B in FIG.

In FIG. 5, the duty ratio of the control signal _S6 is changed to control the average opening degree of the solenoid valve 38, so that the position of the piston 15 is controlled to a position where a desired advance angle value is obtained. control unit 8 for
A block diagram is shown. Control unit 8
is the calculation circuit 8 that calculates and outputs the target advance angle signal _D1 .
1. When the engine temperature is below a predetermined value, the calculation circuit 81 calculates the optimum starting advance angle position _{θ a} of the diesel engine based on the water temperature signal S ₂ . This advance angle position is based on the top dead center position of the diesel engine, and is information that indicates how far from the top dead center position fuel injection should be started.The target advance angle signal _D1 is generated by the error amplifier circuit. 82 is applied to one input. The rotational speed signal S ₂ , top dead center timing signal S ₃ and lift timing signal S ₄ are input to an advance angle detection circuit 83 that detects the actual advance angle position of this internal combustion engine device 1. Outputs the actual advance angle signal _D2 shown. The actual advance angle signal D ₂ is applied to the other input of the error amplification circuit 82, and the error amplification circuit 82 outputs an error signal D ₃ corresponding to the level difference between the two signals D ₁ and D ₂ . The error signal _D3 is sent to the arithmetic circuit 81.
This is a signal indicating the magnitude of the difference between the target advance angle position calculated in 1 and the actual advance angle position, and is input to the duty ratio calculation circuit 84. The duty ratio calculation circuit 84 receives a control signal which is a pulse signal output from the pulse generator 85 in response to the error signal _D3 .
Outputs a command signal _D4 for determining the duty ratio of _S6 . The command signal _D4 is input to the pulse generator 85, and a control signal _S6 with a duty ratio corresponding to the difference between the target advance angle value and the actual advance angle position is obtained, and the solenoid valve 38 is controlled by the control signal _S6 . Opening/closing is controlled.

Therefore, during starting operation, the optimal starting target advance angle θ _a (see FIG. 6) at the current temperature T [°C] calculated by the calculation circuit 81 and the advance angle detection circuit 8
The difference from the actual advance angle θ detected by S 3 is determined in the error amplification circuit 82, and the duty ratio of the control signal S ₆ 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 engine temperature reaches a predetermined value, stable starting operation is already being performed, and next, the optimum target load advance angle value is calculated in the calculation circuit 81 according to the engine load, rotation speed, and engine temperature. Ru. Which type of target advance angle value is calculated in the calculation circuit 81 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 advance value is calculated. An angle value is calculated, and 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. With this control unit 8,
The control operation for setting 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 starting described above, so a detailed explanation will be omitted.

As a result, the advance angle θ with respect to the change in the rotational speed N is
For example, it changes as shown in FIG. 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. The required advance angle position can be maintained until complete detonation. In this case, piston 1
5 is positioned so that the required starting advance angle can be obtained at positions other than both ends of its movable range, so
The piston 15 can be moved in any direction along its axis from its starting advance angle position, thereby making it possible to obtain optimum starting advance characteristics at the time of starting. Therefore, it is possible to improve the starting characteristics, especially during the cold period. 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 it can accurately detect the actual fuel injection start timing, making it extremely useful. Accurate 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, when the pressures in the first and second cylinder chambers are equal, the piston is positioned so that the required starting advance angle is obtained at a position other than both ends of the piston's movable range. Because of this configuration, the piston can be moved in any direction along its axis from its starting advance position, thereby achieving the desired starting injection, especially in the low rotational speed region near and below the idle speed. It has an excellent effect of being able to provide advance angle characteristics.

[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. Fig. 3 shows the characteristics of the timer, Fig. 5 shows the block diagram of the electrical system of the device shown in Fig. 2, Fig. 6 shows the characteristics of the optimum starting target advance angle, and Fig. 7 shows the characteristics of the device shown in Fig. 2. FIG. 3 is a characteristic diagram showing control characteristics. 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...
Resilient spring, 24...Roller holder, 28, 29,
34, 37...Opening, 30,31,35...Aperture, 38...Solenoid valve, 81...Arithmetic circuit, S ₁ ...
Rotation speed signal, S ₂ ... Water temperature signal, S ₃ ... Top dead center timing signal, S ₄ ... Lift timing signal, S ₅ ...
...Load signal, S ₆ ...Control signal, D ₁ ...Target advance angle signal, D ₂ ...Actual advance angle signal, D ₃ ...Error signal, D ₄
...Command signal.

Claims (1)

[Claims] 1. A fuel injection timing adjustment device comprising a piston that drives a roller holder, a cylinder that accommodates the piston so that first and second cylinder chambers are formed at the ends of the piston, and a cylinder that accommodates the piston, and means for positioning the piston so that a required starting advance angle is given at a position other than both end positions of the movable range of the piston when the pressures in the first and second cylinder chambers are equal; means for supplying pressurized fuel whose pressure changes in relation to the engine speed; fixed throttle means provided in the pressurized fuel supply passage and discharge passage of the first cylinder chamber; and the second cylinder chamber. Valve means for adjusting the pressure in the cylinder chamber to a desired value;
A fuel injection timing adjustment device comprising: control means for controlling the opening and closing of the valve means so as to obtain an injection advance according to a predetermined injection advance characteristic in response to a parameter indicating a state of an internal combustion engine device. .