JPH018673Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to a fuel injection timing control device for an engine. (Prior Art) Conventionally, an engine equipped with a fuel injection pump, especially a diesel engine, is equipped with a timer mechanism that sets a reference injection timing according to engine operating parameters such as rotation and load. It is equipped with a variable fuel injection timing mechanism that can advance the injection timing, and can detect and advance the fuel injection timing when low temperatures (e.g., engine coolant temperature is below 40°C) or when driving at high altitudes (e.g., altitudes of 200 m or more) are likely to cause misfires. Therefore, attempts have been made to prevent misfires (for example, see Japanese Patent Laid-Open No. 164736/1983). (Problem to be solved by the invention) However, although advancing the injection timing in this way prevents misfires, there is a problem in that the performance of NOx and other emissions deteriorates. The present invention has been developed in view of the above, and an object of the present invention is to provide a fuel injection timing control device for an engine that can prevent misfires without reducing emission performance when driving at high altitudes where the atmospheric pressure is below a predetermined pressure. That is. (Means for Solving the Problem) In order to achieve the above object, the present invention provides a fuel injection timing variable mechanism that can advance the injection timing with respect to the reference injection timing according to the engine operating parameters. A fuel injection timing control device for an engine equipped with a fuel injection pump having: atmospheric pressure detection means for detecting atmospheric pressure; load detection means for detecting a load state of the engine; temperature detection means for detecting engine temperature; Depending on the state of each detection means, when the atmospheric pressure is below a predetermined pressure and a light load state, and when the atmospheric pressure is below a predetermined pressure, a high load state and a low engine temperature, the fuel injection timing is determined. an actuator that operates the variable fuel injection timing mechanism in an advance direction with respect to the standard injection timing, and stops the operation of the variable fuel injection timing mechanism when atmospheric pressure is below a predetermined pressure, the engine is under high load, and the engine temperature is high; It is characterized by comprising means. In other words, the present invention focuses on the fact that the problem of misfire is severe when driving at high altitudes when the atmospheric pressure is below a predetermined pressure, but it is even more severe when driving at light loads, especially when idling. When the load is low and the load is low, the reference injection timing is advanced relative to the reference injection timing. On the other hand, if you always stop advancing the injection timing under high load conditions, when the engine is cold immediately after starting, it will take time for the engine to warm up even if you press the accelerator, and white smoke will likely occur during that time. In order to prevent this, even under high load conditions, the angle is advanced in low temperature conditions, and is not advanced only in high temperature conditions (see the table on page 5). (Function) Depending on the states of the atmospheric pressure detection means, load detection means, and temperature detection means, the actuator means:
When the atmospheric pressure is below a predetermined pressure and under a light load condition, and when the atmospheric pressure is below a predetermined pressure, under a high load condition and the engine temperature is low, the variable fuel injection timing mechanism is advanced relative to the reference injection timing. When the atmospheric pressure is below a predetermined pressure, the load is high, and the engine temperature is high, the variable fuel injection timing mechanism stops operating. (Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a diesel engine, which is equipped with a fuel injection pump having a variable fuel injection timing mechanism. Reference numeral 2 designates a control lever for the variable fuel injection timing mechanism, which is connected to the actuation rod 3a of the actuator 3, and is moved in the counterclockwise direction A by the operation of the actuator 3.
It is designed to advance when rotated. Reference numeral 4 denotes a water temperature sensor (temperature detection means) which detects the temperature of engine cooling water and issues a low temperature signal _S1 when the temperature is, for example, 40° C. or lower. Reference numeral 5 denotes an atmospheric pressure sensor (atmospheric pressure detection means) which detects atmospheric pressure and issues a high altitude signal _S2 when the atmospheric pressure falls below a set value. Reference numeral 6 denotes a load sensor (load detection means) which detects the load condition of the engine 1 and generates a light load signal _S3 when the load condition is light. The three sensors 4, 5, and 6 are each electrically linked to a control circuit 7 to constitute a control system 8,
The control system 8 (control circuit 7)
A three-way solenoid valve 10 interposed between the air pump 9 and the air pump 9 is switched and controlled. In other words, for example, in the case of an automatic vehicle, as shown in Tables 1 and 2, a) whether you are driving at low altitude or high altitude, and) whether the temperature of the engine cooling water is below 40 degrees Celsius or 40 degrees Celsius. It is controlled according to conditions such as whether the vehicle is in a light load operation (neutral range, parking range) or a high load operation (drive range).

[Table] Advance only the ○ mark.

[Table] As a specific example of the control system 8 in which only the mark ○ is advanced, as shown in FIG.
temperature switch 14, which is an on-off switch that closes when the temperature drops below 2000 m; atmospheric pressure switch 15, which is an on-off switch that closes at high altitudes of 2000 m or higher; and load switch 16 (automatic), which is an on-off switch that closes during light load operation. This is an electric circuit consisting of a neutral range switch (in the case of a manual transmission vehicle) or a parking range switch (in the case of a manual transmission vehicle, an idle switch, etc.), and a relay 17 that switches the three-way solenoid valve 10. 17, temperature switch 14
, an atmospheric pressure switch 15 and a load switch 16 connected in series are connected and wired in parallel. The fuel injection mechanism is configured as shown in FIG. 2, for example. That is, a timer 20 that controls the fuel injection timing has a timer piston 23 that slides within a cylinder 22 formed in a housing 21, and the timer piston 23 is connected to a roller holder 25 via a swingable lever 24. At the same time, a first hydraulic chamber 27 is formed on one side sandwiching the timer piston 23 in the cylinder 22, and a spring 26 is compressed therein, and the suction side fuel pressure of a feed pump (not shown) acts thereon.
Further, on the other side, a second hydraulic chamber 30 is formed on which the fuel pressure of the pump chamber 29 acts via a hydraulic passage 28 provided in the timer piston 23, and a first hydraulic chamber 30 is formed on the other side.
7 and the second hydraulic chamber 30 (that is, the fuel pressure according to the engine speed) and the elastic force of the spring 26, the position of the timer piston 23, that is, the circle of the roller holder 25 via the lever 24 is adjusted. The circumferential position is determined, and this roll holder 25
Due to the change in the circumferential position of the drive shaft 31, a relative change occurs between the circumferential phase of the drive shaft 31 and the operating position of the plunger (not shown), thereby changing the fuel injection timing with respect to the rotation of the drive shaft 31, Accordingly, when the differential pressure is large, the timer piston 23 is moved to the left (in FIG. 2) against the elastic force of the spring 26 according to the differential pressure, and the roll holder 25 is moved clockwise. It is configured to advance the fuel injection timing by rotating in the direction. Further, since the rotation shaft 33 of the eccentric cam 32 engaged with the roller holder 25 is rotatably supported by the housing 21, and the control lever 2 is pivotally attached to the end projecting from the housing 33, By retracting the actuating rod 3a of the actuator 3 and rotating the control lever 2 in the counterclockwise direction A, the eccentric cam 32 is rotated, the roll holder 25 is rotated clockwise, and the fuel injection timing is advanced. can be done. With the above configuration, as shown in Tables 1 and 2, when the temperature of the engine cooling water is 40°C or lower, the temperature switch 14 closes and the relay 17 is energized. The three-way solenoid valve 10 connects the air pump 9 to the actuator 3, and pressurized air is supplied to the actuator 3. As a result, the phase is advanced by a predetermined angle, and misfires are prevented. On the other hand, when the engine coolant temperature is 40°C or higher, both the temperature switch 14 and the atmospheric pressure switch 15 are opened when driving at low altitudes.
The relay 17 is not excited, the pressurized air from the air pump 9 is relieved through the air hole 10a, and the phase is not advanced. Therefore, the emission performance is good. If the cooling water temperature is 40°C or lower when driving at high altitudes, the temperature switch 14 is open and the load switch 16 is open during high loads.
The phase does not advance as when driving at low altitudes, but when the load is low, atmospheric pressure switch 15 and load switch 1
6 are both closed, the relay 17 is energized and the three-way solenoid valve 10 switches to connect the air pump 9 to the actuator 3, thereby advancing the phase. In the above embodiment, the actuator 3 is actuated by the switching operation of the three-way solenoid valve 10 to advance the phase, so the amount of advance is constant. If the actuator 3 is directly controlled by
As shown in FIG. 5 (during low-altitude driving and high-load driving at high altitude) and FIG. 6 (during low-load driving at high altitude), control can be performed according to the temperature of the engine cooling water or atmospheric pressure. In FIG. 4, a temperature signal S ₅ from a temperature sensor 41 and an atmospheric pressure signal S ₆ from an atmospheric pressure sensor 42 are shown.
are transmitted to analog switches 45, 46, and 47 via differential amplifier circuits 43 and 44, respectively. On the other hand, the atmospheric pressure signal _S6 is also transmitted to a comparator 48, and the comparator 48 determines whether the vehicle is traveling at high altitude or low altitude. When driving at low altitudes, a low altitude signal _S7 is output to the analog switch 46 via the diode 49, which operates the actuator 3 in accordance with the temperature of the engine coolant, thereby controlling the rotation angle of the control lever 2. (See Figure 5). In addition, when driving at high altitudes, the output is output to AND circuits 51 and 52 via another diode 50;
52 receives the light load signal _S8 and high load signal S9 from the light load switch 53 and the high load switch ₅₄ , respectively, so during light load operation at high altitudes and high load operation at high altitudes,
Analog switch 47 from AND circuits 51 and 52,
45, the advance angle is controlled according to the atmospheric pressure or the temperature of the engine cooling water (see FIG. 6 for the former and FIG. 5 for the latter). In this way, analog switches 45, 46, 4
7 outputs a control signal _S10 corresponding to the engine coolant temperature or atmospheric pressure to the actuator 3,
Advance angle is controlled. (Effects of the invention) As described above, the present invention advances the injection timing when driving at high altitudes under light load conditions such as idling, and advances the injection timing when driving at high altitudes under high load conditions.
In high-temperature conditions, the engine operates at the standard injection timing in the same way as when driving at low altitudes, but in low-temperature conditions, it is configured to advance the injection timing. It can prevent misfires, and even under high load conditions when driving at high altitudes, the engine is advanced in cold conditions, improving combustibility, and when the engine is cold immediately after starting, it will not turn off until the engine warms up. There is no problem of smoke generation.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of an engine fuel injection timing control device, FIG. 2 is a sectional view of a fuel injection timing variable mechanism of a fuel injection pump, and FIG. Control system electrical circuit diagram,
FIG. 4 is an electric circuit diagram of another control system, and FIGS. 5 and 6 are characteristic diagrams of the control system of FIG. 4. 1... Diesel engine, 2... Control lever, 3... Actuator, 4... Water temperature sensor,
5...Atmospheric pressure sensor, 6...Load sensor, 7...
Control circuit, 8... Control system, 14... Temperature switch, 15... Atmospheric pressure switch, 16... Load switch, 17... Relay, 40... Control system, 41...
... Temperature sensor, 42 ... Atmospheric pressure sensor, 53 ...
Light load switch, 54...High load switch.

Claims (1)

[Scope of utility model registration request] Atmospheric pressure is detected in a fuel injection timing control device for an engine equipped with a fuel injection pump having a variable fuel injection timing mechanism capable of advancing the injection timing relative to a reference injection timing according to engine operating parameters. An atmospheric pressure detection means, a load detection means for detecting the load state of the engine, a temperature detection means for detecting the engine temperature, and depending on the state of each of the detection means, the atmospheric pressure is below a predetermined pressure and the load is light. When the atmospheric pressure is below a predetermined pressure, the engine is under high load, and the engine temperature is low, the fuel injection timing variable mechanism is operated in an advance direction with respect to the reference injection timing, so that the atmospheric pressure is lower than the predetermined pressure. Hereinafter, a fuel injection timing control device for an engine is characterized in that it includes actuator means for stopping the operation of the variable fuel injection timing mechanism when the engine is in a high load state and the engine temperature is high.