JPH037544Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a boost compensator for compensating the fuel injection amount according to the boost pressure in a supercharged diesel engine.

(Prior art) Conventionally, in a diesel engine equipped with a supercharger in the intake passage, a system that controls the amount of fuel injected from a fuel injection pump with high responsiveness to changes in supercharging pressure has been used. A boost compensator is known that is equipped with a control rod that slides in the direction of the fuel injection amount, and a correction lever that has one end linked to the fuel injection amount adjusting member of the governor mechanism and the other end that comes into contact with a tapered part formed on the side surface of the control rod. It is being In this device, as the control rod is displaced in the axial direction, the compensation lever rotates and moves the fuel injection amount adjustment member, thereby compensating the fuel injection amount according to the boost pressure. ing. However, combustion conditions are affected not only by boost pressure, but also by combustion time, that is, engine speed, and because the base compression ratio of a supercharged engine is relatively low, such compensation alone is insufficient to improve engine performance. As the rotation speed increases, smoke becomes more likely to occur,
Further, when the engine speed is relatively low, there is a problem that fuel is insufficient and the output is reduced.

For this reason, in Japanese Utility Model Application Publication No. 57-31539, the control rod (cam rod) is slid by a diaphragm device equipped with a chamber for introducing supercharging pressure, and in opposition to the diaphragm device, It has been proposed that a correction device is provided to suppress the stroke amount of the control rod in the direction of increasing the amount of fuel in accordance with the increase in engine rotational speed using the exhaust pressure or the fuel pressure in the fuel injection pump. However, with this structure, the amount of movement of the control rod is suppressed, so at the same rotation speed, the increase in fuel injection amount is suppressed more than necessary during high supercharging, resulting in a decrease in output, and when low supercharging The amount of smoke generated increased, making it difficult to properly satisfy engine requirements.

(Purpose of the invention) The present invention solves these conventional problems. It satisfies the output required of the engine, reduces smoke at high engine speeds, and adjusts the amount of fuel injection according to the engine speed. It is an object of the present invention to provide a boost compensator for a supercharged diesel engine that can appropriately perform correction.

(Structure of the invention) The present invention is a boost compensator for a diesel engine that is equipped with a control rod that slides according to the boost pressure and a correction lever that responds to the control rod to compensate for the boost pressure of the fuel injection amount. In this method, the taper angle of the taper part of the control rod is set to a different angle in each part in the circumferential direction, and when the engine is running at low speed, a correction lever is brought into contact with the gently sloped part of the taper part where the taper angle is small, and the engine speed is As the engine rises, the control rod is rotated to bring the correction lever into contact with the steeply sloped part of the taper part, which has a larger taper angle as the engine speeds up, and as the engine speeds up, the fuel injection amount is corrected to decrease. A rotation correction device is installed to reduce the rate of increase in fuel injection amount as the boost pressure increases when the engine is running at low speeds, and to reduce the boost pressure as the engine speeds up, depending on the boost pressure and engine speed. This configuration is configured to increase the rate of increase in the fuel injection amount as the amount of fuel increases. In other words,
In this type of boost compensator, by moving the control rod in the axial direction according to the boost pressure, the fuel injection amount is corrected so that it decreases at a relatively low boost pressure and increases at a relatively high boost pressure. However, in particular, according to the present invention, when the engine is running at high speeds when the correction lever comes into contact with the steeply sloped part of the tapered part, fuel injection is performed when the boost pressure is lower than at low speeds when the correction lever comes into contact with the gently sloped part. The fuel injection amount decreases significantly, and the rate of increase in the fuel injection amount increases as the boost pressure increases.

(Example) In FIG. 1, 1 is a fuel injection pump, and the figure shows a distribution type fuel injection pump.
This pump 1 includes a plunger 3 inserted into a plunger insertion hole 2, and the plunger 3 is driven by a drive shaft (not shown) via a cam disk 4 etc. to rotate and reciprocate. The structure is such that fuel is distributed and supplied from the pump chamber 5 to the injection nozzles of each cylinder. As a fuel injection amount adjusting member of the pump 1, a control sleeve 7 is slidably fitted onto the plunger 3 so as to control the fuel injection amount by adjusting the timing of opening the cut-off port 6 of the plunger 3.
and a lever mechanism such as a tension lever 8 for operating the control sleeve 7. Then, the position of the control sleeve 7 is adjusted by the centrifugal speed governor 9 via the lever mechanism, and the governor spring 1 is adjusted by the control lever 10 linked to the accelerator pedal.
1 and a tension lever 8, the control sleeve 7 is actuated.

The boost compensator that compensates for the boost pressure of the fuel injection amount consists of a control rod 13 that is slidably housed in a cylindrical portion 12 provided at the top of the casing of the pump 1, and a control rod 13 that is rotated around a shaft 15. A movably supported correction lever 16 is provided. One end of this correction lever 16 is in contact with the tension lever 8, and the tip of a pin 17 fixed to the other end of the correction lever 16 is in contact with a tapered portion 14 formed on the lower outer peripheral surface of the control rod 13. There is. In addition, the control rod 13
is adapted to be slid by a diaphragm device 20 according to the boost pressure. That is, the diaphragm device 20 has a supercharging pressure chamber 22 and an atmospheric pressure chamber 23 separated by a diaphragm 21, and the upper supercharging pressure chamber 22 has a supercharging pressure chamber 22 provided in an intake passage (not shown). The supercharging pressure is introduced from the downstream of the supercharger as shown by the arrow in the figure, and the atmospheric pressure chamber 23 is open to the atmosphere, and this chamber 23 is equipped with a spring 24, and the diaphragm A control rod 13 is connected to 21. In this way, as the boost pressure introduced into the boost pressure chamber 22 increases, the control rod 13 is pushed down by the diaphragm 21.

Furthermore, the control rod 13 is adapted to be rotated in response to changes in engine speed. That is, the control rod 13
is interlocked and connected to a rotational actuator 28 using a linear solenoid or the like through a transmission mechanism consisting of a pinion 26 provided at the intermediate portion and a rack 27 meshing with the pinion 26, etc., and the actuator 2
8 is driven by a control circuit 30 that receives a signal from an engine rotation speed sensor 29.

As shown in detail in FIG. 2, the tapered portion 14 of the control rod 13 is formed so that the diameter becomes larger toward the bottom and the taper angle differs at each portion in the circumferential direction. In FIG. 2, the right side of the tapered portion 14 is a gently sloped portion 14a with the smallest taper angle, and the left side is a steeply sloped portion 14b with the largest taper angle. The distance to the surface is steeply inclined part 14b
It is designed to become larger as the size increases. and,
When the engine is running at a low speed, the gently inclined portion 14a is connected to the pin 17 of the correction lever 16, as shown in FIG. 3A.
The actuator 28 is controlled by the control circuit 30 so as to rotate the control lever 13 so that the steeply inclined portion 14b contacts the pin 17 as shown in FIG. 3B at high rotation speeds. There is.

In this structure, as the boost pressure increases, the control rod 13 is pushed down by the diaphragm device 20, and the pin 1 of the correction lever 16 is pushed down.
Since the contact position with 7 moves upward to the smaller diameter side of the tapered portion 14, the correction lever 16 rotates clockwise from the state shown in FIG. Accordingly, the control sleeve 7 is moved to the right side in the figure via the tension lever 8, thereby delaying the timing at which the cut-off port 6 opens (the end of fuel injection) and increasing the amount of fuel. .

Furthermore, when the engine speed is low, the fuel injection amount is adjusted according to the boost pressure with the pin 17 of the correction lever 16 in contact with the gently sloped part 14a of the tapered part 14 of the control rod 13. However, when the engine speed increases, the control rod 13 is rotated so that the pin 17 is in contact with the steeply inclined part 14b of the tapered part 14.
As a result, the fuel injection amount is corrected to decrease. That is, when the control rod 13 having the shape shown in Fig. 2 is used to check the amount of correction of the fuel injection amount according to the change in boost pressure, it is found that the engine speed is 1000.
~2500rpm, it becomes as shown by solid line A in Figure 4, and when the engine speed is 4000rpm, it becomes as shown by broken line B in the same figure.
It will be shown as follows. In this graph, when the fuel injection amount reaches its maximum due to an increase in boost pressure (when the pin 17 comes into contact with the minimum diameter portion of the upper end of the tapered portion 14 of the control rod 13), the correction amount of the fuel injection amount is determined. is set to 0, and the correction amount of the fuel injection amount is expressed on the vertical axis based on this value. As can be seen from this graph, according to the shape of the control rod 13 shown in Figure 2, when the engine is running at high speeds compared to when the engine is at low speeds, when the boost pressure falls below a certain level, the amount of fuel injection decreases rapidly. This effectively prevents the occurrence of smoke, and at low engine speeds and high supercharging, the fuel injection amount required in each case can be obtained.

The angle of inclination of each part in the circumferential direction of the tapered portion 14 of the control rod 13, the amount of rotational displacement of the control rod 13 depending on the engine speed, etc. can be selected from various designs. The characteristics of the correction can be easily set and adjusted so that the fuel injection amount is corrected appropriately in accordance with the engine's requirements for ensuring fuel injection amount and reducing smoke.

(Effects of the invention) As described above, the present invention makes the taper angle of the taper part of the control rod in the boost compensator different at each part in the circumferential direction, and when the engine rotates at low speeds, the taper part is corrected to a gently sloped part. By contacting the lever and rotating the control rod according to the engine speed, the correction lever is brought into contact with the steeper slope of the tapered part as the engine speeds up. The fuel injection amount is largely reduced on the boost pressure side, so that the rate of increase in the fuel injection amount as the boost pressure increases is increased. Therefore, while fuel shortage is prevented at low engine speeds, when the engine is at high speeds, fuel reduction correction prevents the occurrence of smoke, and the rate of increase in fuel as the boost pressure increases increases the fuel overload. The fuel injection amount can be appropriately corrected so that the output in the fuel supply state is ensured, that is, the required output of the engine is satisfied, and smoke is reduced at high engine speeds. Furthermore, since the control rod is used to perform the correction, the structure can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of the entire fuel injection pump showing an embodiment of the device of the present invention, Fig. 2 is an enlarged view of the control rod, and Figs. Explanatory diagram showing the positional relationship between the control rod and the pin of the correction lever in 4th
The figure is a graph showing the relationship between the boost pressure and the correction amount of the fuel injection amount at low engine speed and high engine speed. DESCRIPTION OF SYMBOLS 1... Fuel injection pump, 8... Tension lever, 13... Control rod, 14... Taper part, 16... Correction lever, 28... Actuator for rotating the control rod, 29... Engine rotation speed sensor.

Claims (1)

[Scope of utility model registration request] A control rod that slides in the axial direction according to boost pressure, and a correction lever that has one end linked to a fuel injection amount adjustment member and the other end that comes into contact with a tapered portion formed on the side surface of the control rod, In a boost compensator for a supercharged diesel engine that compensates the fuel injection amount according to the axial displacement of the control rod, the taper angle of the tapered part of the control rod is made different at each part in the circumferential direction. At low engine speeds, the correction lever is brought into contact with the gently sloped part of the taper section with a small taper angle, and as the engine speed increases, the control rod is rotated to adjust the angle of the taper section where the taper angle is large as the engine speed increases. A rotation correction device is installed that corrects the fuel injection amount in the direction of decrease as the engine speed increases, by placing a correction lever in contact with the steeply sloped part. A supercharging system characterized in that the rate of increase in the amount of fuel injected as the boost pressure increases is reduced, and the rate of increase in the amount of fuel injected as the boost pressure increases is increased as the engine speed increases. Boost compensator for diesel engine.