JPS6332921Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a fuel supply control device for a diesel engine that cuts injected fuel in accordance with a predetermined fuel cut range.

For example, in the case of a diesel engine, a fuel injection pump as illustrated in FIG. 1 is known, which not only pumps fuel under pressure but also mechanically controls the amount of fuel to be injected. More specifically, the drive shaft 1 is driven by an engine, thereby rotating a vane type feed pump 2 and a cam disc 3. The fuel whose feeding pressure has been increased by the feed pump 2 enters the plunger barrel 6 from the pump chamber 4 via the fuel suction passage 5. On the other hand, a number of surface cams corresponding to the number of cylinders are protruded from the cam disk 3, and a plunger 7 connected to the cam disk 3 rotates for distribution and reciprocates for pumping fuel. at the same time. The fuel compressed to high pressure by the plunger 7 is sent to an injection nozzle (not shown) through a delivery valve 9 from distribution ports 8, which are provided as many as the number of cylinders. And the adjustment of the injection amount is
This is achieved by adjusting the position of the control sleeve 10 to change the leak timing of the compressed fuel, that is, by changing the compression stroke of the plunger 7. The position of the control sleeve 10 is controlled by a control lever 11 that is linked to an accelerator pedal (not shown) via a wire, and a centrifugal cabana 12, and thereby the fuel injection characteristics ( cabana characteristics) (see Nissan Motor Co., Ltd. Service Bulletin No. 418, ``Datsutosan Bluebird'', published in April 1980).

However, in the conventional configuration in which fuel is mechanically controlled in this way, the fuel cut during coasting occurs when the accelerator pedal is not depressed and at the same time the centrifugal cabana 12 rotates above the set rotation speed. In this case, the control sleeve 10 is mechanically positioned at the no-injection position, so even during coasting, fuel is injected in the area, which is a wasteful area as shown by diagonal lines in FIG. Therefore, the fuel efficiency savings due to fuel cutting are not utilized to the fullest extent. Furthermore, in terms of preventing engine overruns, the operating speed of the overrun prevention mechanism varies by about ±200 rpm from the set speed due to the mechanical cabana.

Furthermore, in the past, no mechanism such as a throttle valve was provided to limit intake air in conjunction with fuel cut, and although it is possible to reduce friction loss during fuel cut by limiting intake air, no consideration was given to this. Not yet. Therefore, for example, if the engine brake is too effective, it is necessary to depress the accelerator to generate engine torque even if the vehicle is going downhill, which is not preferable from the standpoint of fuel economy.

This invention was made in view of these conventional problems, and it electrically detects the accelerator pedal position and engine speed, and determines the appropriate amount of fuel injection based on both detection signals.
Additionally, an intake throttle valve mechanism is provided to maximize the use of the fuel cut area.

FIG. 8 is a diagram corresponding to claims showing the configuration of this invention, where A is an accelerator pedal position detection device consisting of a potentiometer etc. that detects the accelerator pedal position, and B is an engine speed detection device that detects the engine speed (rotation number). The device C is a control circuit consisting of, for example, a microcomputer, which is a means D for calculating the output signals of both the detection devices A and B to determine the fuel injection amount of the fuel injection pump.
and a means E for determining whether or not the fuel is within a predetermined cut range based on the output signals of both the detection devices A and B, and for issuing a fuel cut signal. Further, F is a fuel metering mechanism in the fuel injection pump controlled by the control circuit C, G is a fuel cut mechanism that cuts off fuel supply to all cylinders at once in response to the fuel cut signal, and H
Similarly, in response to the fuel cut signal, the intake throttle valve mechanism throttles the engine intake passages of all cylinders during fuel cut.

In the above configuration, an appropriate amount of fuel injection is always given based on the accelerator pedal position and engine speed. When operating conditions fall into a predetermined cut range, such as during deceleration, the fuel cut mechanism cuts fuel to all cylinders simultaneously, and at the same time, the intake throttle valve mechanism throttles the engine intake passage, allowing all cylinders to Inflow of intake air is suppressed.

Hereinafter, one embodiment of this invention will be described in detail based on the drawings.

FIG. 3 shows a fuel injection pump according to this invention, and parts that are not particularly different from those in FIG. 1 are given the same reference numerals. That is, in this case, the control sleeve 10 as a metering mechanism is directly driven by the electric actuator 21 without using a centrifugal cabana or the like, and there is a valve in the middle of the fuel intake passage 5. A fuel cut valve 22 made of a solenoid valve is provided as a fuel cut mechanism. Incidentally, this fuel cut valve 22 can be used as a stopper valve conventionally provided to prevent run-on.

FIG. 4 is a block diagram of the control device of the present invention.
21 and 22 are the above-mentioned electric actuators, respectively;
Fuel cut-off valve is shown. The control circuit 23 is a so-called microcomputer, and is composed of a microprocessor, ROM, RAM, etc., and the ROM stores processing programs and a control map to be described later. Accelerator pedal position detection sensor 24
is composed of, for example, a potentiometer, and detects the position of the accelerator pedal, that is, the amount of depression. The engine speed detection sensor 25 is configured, for example, by an electromagnetic pickup mechanism to generate pulses in synchronization with the rotation of the crankshaft, and detects the engine speed (rotation number). Reference numeral 26 indicates an electric actuator for the intake throttle valve mechanism, which is capable of completely closing the engine intake passage using, for example, a solenoid.

The control circuit 23 calculates the output signals of the accelerator pedal position detection sensor 24 and the engine speed detection sensor 25, and calculates the control sleeve 10 position, that is, the fuel injection amount, based on the control map (θ-N map) shown in FIG. is determined to drive the actuator 21, and a fuel cut signal is output to the fuel cut valve 22 and the actuator 26 in an area corresponding to a predetermined cut area (shaded area). In the above control map,
The fuel cut area is set to an opening slightly below the No-Load line (dotted chain line), that is, the full cutting range, allowing fuel cut to be performed over a wider range than the conventional fuel cut area A. It will be done.

Next, to explain the operation of the control device of the present invention, first, the pedal stroke (θ) detected by the accelerator pedal position detection sensor 24 and the engine speed (N) detected by the engine speed detection sensor 25 are compared as shown in FIG. The sliding stroke of the control sleeve 10 is set from the control map,
Actuator 21 is driven. When the pedal stroke (θ) and the engine speed (N) enter the cut range on a downhill slope, the fuel cut valve 22 operates to cut off the fuel supply. At the same time, the actuator 26 operates to cut off the intake air, reducing friction during fuel cut and improving the coasting performance of the vehicle. Incidentally, during this cutting, the control sleeve 10 is controlled to the No-Load position, so that the cutting can be smoothly released.

When the engine speed (N) increases and exceeds the set value (for example, 5200 rpm), fuel cut is performed with the highest priority as shown in the flowchart in Figure 6 to prevent overrun. .
If the program is configured to control the control sleeve 10 to the non-injection position during this fuel cut, overrun can be reliably prevented even if the fuel cut valve 22 does not operate.

Furthermore, as mentioned above, if intake air is cut off when fuel is cut to reduce friction loss, engine braking becomes unavailable. As shown in the flowchart of FIG. 7, engine braking can be used in the same way as before by reducing the throttle amount or fully opening the intake throttle valve when the brake is depressed.

As is clear from the above explanation, according to this invention, the fuel cut range can be set to the full possible fuel cut range, so fuel efficiency is greatly improved, and
Since coasting performance is improved by reducing friction loss, fuel efficiency can be further improved, and overruns can be reliably prevented at precisely set rotation speeds.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional explanatory diagram showing an example of a conventional fuel supply control device, Fig. 2 is a cabana characteristic diagram thereof,
Fig. 3 is a cross-sectional explanatory diagram of the fuel injection pump according to the invention, Fig. 4 is a block diagram of the control device of the invention, Fig. 5 is a diagram showing a control map in the control circuit, and Fig. 6 is a flowchart of the control circuit. , Figure 7 is a flowchart when using engine brake,
FIG. 8 is a claim correspondence diagram showing the structure of this invention. DESCRIPTION OF SYMBOLS 10...Control sleeve, 21...Electric actuator, 22...Fuel cut valve, 23
... Control circuit, 24 ... Accelerator pedal position detection sensor, 25 ... Engine speed detection sensor,
26...Electric actuator for throttle valve.

Claims (1)

[Scope of utility model registration request] The accelerator pedal position detection position, the engine speed detection device, a means for calculating the output signals of both detection devices to determine the fuel injection amount of the fuel injection pump, and whether the output signal of both detection devices is within a predetermined cut range. a control circuit having means for determining whether or not the fuel is cut and issuing a fuel cut signal; a fuel metering mechanism in a fuel injection pump controlled by the control circuit;
A fuel cut mechanism that simultaneously cuts off fuel supply to all cylinders in response to the fuel cut signal, and an intake throttle valve mechanism that throttles the engine intake passages of all cylinders during fuel cut in response to the fuel cut signal. Fuel supply control device for diesel engines.