JP2510330Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to improvement of a fuel injection device for an internal combustion engine.

[Conventional technology]

FIG. 6 shows an example of a conventional fuel injection device for an internal combustion engine.

In a diesel engine having the fuel injection pump 2, it is necessary to supply an amount of fuel oil corresponding to the load of the engine into the cylinder 1 via the fuel injection pipe 3. Generally, the fuel injection valve 4 installed in the cylinder head is used with the area of its injection hole being constant, so if the fuel increased in amount as the load increases is pumped from the fuel pump, The fuel pressure inside the injection pipe tends to increase as the load increases.

In an internal combustion engine having such a fuel injection device, it is usually used for a certain fixed load for almost the entire period, but rarely when it is used at a higher load, for example, the maximum allowable load. Causes the following problems.

That is, in the conventional fuel supply system as shown in FIG. 6, the fuel is usually used at the point A of the normal load for almost the entire period as shown in FIG. _A
Indicated by. If the point of maximum allowable load used only in a specific case is indicated by B, the same fuel pressure at this point _B is p _B
It will rise up to. Therefore, even with a limited frequency, in an engine that may be used at the point B, all the fuel injection devices including the fuel injection pump 2, the high-pressure fuel injection pipe 3, the fuel injection valve 4, etc. It is necessary to stop within the maximum pressure p _B allowed by the design, and it is normally used A
At this point, it is unavoidable to use it at a fuel pressure P _A which is lower than p _B by ΔP.

Generally, in a fuel injection device for an internal combustion engine, the higher the fuel injection pressure, the shorter the time required to inject the necessary fuel into the cylinder, and the finer the injected fuel particles, so the engine cycle Efficiency and combustion effect are good,
It tends to be possible to reduce fuel consumption. Therefore, in an engine that uses the above-mentioned method, even if the point A is a normal load that is used most of the time, the point B is a high load that is used only rarely. In preparation for point _A , there is a problem that the fuel injection pressure p _A that cannot be said to be lower than the level that is usually allowed in the design must be used at point _A.

[Problems to be solved by the invention]

The present invention has been made to solve the above-mentioned problems, and in the main area including the normal load, the fuel injection pressure is made as close as possible to the maximum pressure allowed by the fuel injection device, and good cycle efficiency is achieved. It is intended to realize reduction of fuel consumption by obtaining combustion efficiency.

That is, the object of the present invention is to solve the problems of the above-mentioned conventional device, and to maintain the same maximum pressure as the full load even in the normal load to improve combustion, minimize the fuel consumption, and improve the durability of the engine. An object of the present invention is to provide an internal combustion engine and a fuel injection device for the internal combustion engine which are highly economical and have improved reliability.

[Means for solving problems]

The fuel injection device for an internal combustion engine according to the present invention is a jerk type fuel pump whose pump head is secured only by a change in injection timing so that the usage range is a high front speed with respect to the cam angle, and a pump rack. Sensors for respectively detecting the position and the engine speed, a control device for inputting the outputs of these sensors and a control map to output a control signal for fuel injection timing, and a control device for the variable timing fuel injection device via the control device. It is characterized by having an actuator for changing the timing.

[Action]

At low and high loads other than the rated load, the injection timing is changed by the variable timing injection pump to move the fuel cam operating range and select the cam speed so that the fuel speed in the high-pressure injection pipe becomes almost constant. Since this is done, the injection pressure can be made substantially constant in all load regions.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is an engine cylinder, 2 is a fuel injection pump, 3 is a fuel injection pipe, 4 is a fuel valve, 5 is a fuel cam with a large lift so that the operating range can be changed, 8 is a fuel tank, and 9 is A fuel supply pump, 10 is a control device which inputs the outputs of the position sensor of the fuel injection pump rack and the engine speed sensor and a control map, 11 is an actuator, and 12 is a link device.

The fuel is pressurized from the tank 8 via the supply pump 9,
It is supplied to the injection pump 2. Further, the fuel is pressurized to a high pressure by the fuel injection pump 2 driven by the fuel cam 5, and is injected from the fuel valve 4 into the cylinder 1 through the high pressure injection pipe 3. The fuel cam 5 has a cam angle θ as shown in FIG.
On the other hand, the cam speed v is changed to the front high, that is, the cam speed v is maximized early (when the cam angle θ is small), and the maximum lift l _max is the discharge start θ at the rated time. _s from the timing change allowance [Delta] [theta] _(-) or [Delta] [theta] ₍₊₎ only the discharge period theta _d corresponding to the injection quantity at the maximum injection also move are provided so as to ensure. The broken line l in the figure indicates the cam lift. In the present invention, since the mode of the cam speed v is front high, the discharge start θ _s (the range of use of the cam)
By changing the, the cam speed in the use range changes, and the injection pressure increases or decreases corresponding to this speed change.

The present invention utilizes this principle to increase the injection pressure at partial load.

During the normal period, the use area of the cam is fixed, and the lift amount of the cam only needs to be an amount commensurate with this use area. In the present invention, the use range of the cam is moved by changing the discharge start θ _s . The cam lift l needs to be larger than usual so as to correspond to the movement of the use area.

For this reason, in the present invention, the cam shape is such that the cam lift corresponding to the discharge period θ _d corresponding to the maximum injection amount is secured even when the use range of the cam is moved. Normally, the fuel injection pressure P is substantially proportional to the engine speed and the cam speed v. The solid line in Fig. 3 is the measurement result when the discharge start θ _s is changed by the variable timing injection pump using the fuel cam in Fig. 2 and the operation range of the cam is changed, and the discharge start θ _s is used as a parameter. The horizontal axis shows the engine load L and the vertical axis shows the injection pressure p. In the figure 10
Design injection pressure at 0% load When the discharge start θ _s is fixed to a constant value, the change in the engine load L indicates the rated point (100% load) as shown by the thick solid line.
Before and after, the injection pressure p increases and decreases. The thin solid line shows the injection pressure p when the cam angle θ is made large or small and the timing is delayed or advanced. Therefore, by changing the discharge start θ _{s according} to the magnitude of the load L, the injection pressure p can be maintained at a constant value as indicated by the broken line and the mark.

FIG. 4 is a diagram showing in solid lines the discharge start θ _s selected so that the injection pressure becomes the design pressure p for each load L. That is, in the jerk type variable timing type fuel injection pump having the fuel cam 5 as shown in FIG. 2, the injection start θ _s is set as shown in FIG. 4 to make the injection pressure p constant at all loads. You can

Fig. 5 shows the changing tendency of the maximum cylinder pressure p _max with respect to the load L. When there is no timing change by the fuel cam, it shows the solid line, and the maximum cylinder pressure p at the rated point 100% load p _max It shows with. Since the maximum cylinder pressure p _max tends to increase as the injection timing advances, p _max can be made constant as indicated by the broken line by setting the advance amount of the discharge start θ _s to Δθ _(±). . That is, a constant value of p _max can be maintained by selecting the inclination mode of the speed v in the usage range of the fuel cam 5.

It should be noted that the injection pressure p and the maximum cylinder pressure p _max are not horizontal as indicated by the broken line, and may be set to any inclination in determining the combustion state of the engine.

Further, the maximum cylinder pressure p _max can be controlled by providing a variable nozzle area supercharger and adjusting the nozzle area to change the scavenging pressure.

[Effect of device]

According to the present invention, since the fuel injection pressure can be maintained at the design pressure p at the rated point 100% load over all loads of the engine, the fuel consumption can be minimized and combustion can be improved. An economical internal combustion engine with improved durability and reliability can be realized.

[Brief description of drawings]

1 to 5 relate to the present invention. FIG. 1 is a structural view of an embodiment, FIG. 2 is a fuel cam diagram, and FIG. 3 is a load L and an injection pressure p with a discharge start θ _s as a parameter. Relationship diagram between,
FIG. 4 is a diagram _showing the relationship between the load L for keeping the injection pressure p constant and the discharge start θ _s , and FIG. 5 shows the discharge start θ _{s, that} is, the load L and the cylinder maximum pressure p _max when the injection timing is fixed. A relational diagram (solid line) and a diagram showing that the maximum cylinder pressure p _max can be kept constant as shown by a broken line by changing the injection timing, FIGS. 6 to 7 are conventional examples, and FIG. 6 is a conventional example structure. The solid line in FIGS. 7A and 7B is a relational diagram between the load L and the pressure p in the fuel injection pipe. 2 ... Variable timing fuel injection device, 5 ... Fuel cam, 11 ... Actuator, 12 ... Control device.

Claims (1)

(57) [Scope of utility model registration request] 1. A jerk-type variable timing fuel injection device for an internal combustion engine, comprising: a fuel cam whose head is secured only by an injection timing change margin so that a use range is mainly a speed higher than a cam angle. Sensors for respectively detecting the pump rack position and the engine speed, a control device for inputting the outputs of these sensors and a control map and outputting a control signal for fuel injection timing, and the variable timing type according to the control signal from the control device. A fuel injection device for an internal combustion engine, comprising: an actuator for changing the timing of the fuel injection device, and maintaining the fuel injection pressure of the rated load by adjusting the injection timing during operation. .