JPH0467571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply control device, and more particularly to a device that controls fuel supply using control signals from an electronic control device.

A diesel engine is equipped with a fuel injection pump, which sequentially supplies fuel to each cylinder of the engine. The amount of fuel supplied by the fuel injection pump is controlled by moving the control rack of the fuel injection pump via a mechanical governor attached to the fuel injection pump using a load lever that is linked to the accelerator pedal. was. Control of fuel supply by a fuel injection pump using a conventional mechanical governor is inferior in accuracy and cannot perform various complex controls such as economical driving or constant speed driving. This had the disadvantage that the engine could not fully demonstrate its functions. In order to overcome these drawbacks, attempts have been made to control the fuel supply using an electronic control device such as a microcomputer. The problem is how accurately the control rack of the fuel injection pump can be driven using the control signal from the fuel injection pump.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a device that controls fuel supply with high precision using a simple mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a fuel supply control device for a diesel engine will be described below with reference to the drawings. As shown in FIG. 1, a fuel injection pump 2 is attached to a side surface of a diesel engine 1. The fuel injection pump 2 is driven by a cam fixed to a camshaft 5 which is driven via a gear 3 and a timer 4 by the rotation of the engine. That is, the fuel injection pump 2 has the same number of pump units 6 as the cylinders of the engine 1, for example, six pump units 6, which are driven by respective cams provided on the camshaft 5 to supply fuel. Fuel is sequentially supplied into the cylinders of the engine 1 via a pipe 7.

The fuel injection pump 2 is also equipped with a control rack 8, which controls the amount of fuel supplied by each pump unit 6 at one time. The control rack 8 is adapted to be controlled by a step motor 9 fixed to the casing of the fuel injection pump 2. A control signal is supplied to the step motor 9 from a microcomputer 10. The microcomputer 10 receives a detection output from a sensor 12 that detects the amount of depression of the accelerator pedal 11, a detection output from a rotation detection sensor 13 that detects the number of revolutions of the engine 1, and the position of the rack provided on the step motor 9. Detection outputs from the detection sensors 14 are respectively input. Although not shown here, the microcomputer 10 also receives information such as the gear ratio of the transmission, the traveling speed of the vehicle, a signal for setting the traveling state, the state of the clutch, the presence or absence of brake operation, the outside temperature, Various information such as engine coolant temperature and engine oil temperature are input.

Next, the structure of the step motor 9 and the connection structure between the step motor 9 and the control rack 8 will be explained with reference to FIGS. 2 to 4. Coils 15 are fixedly attached to both sides of the inner circumference of the casing of the step motor 9. A cylindrical stator 16 is fixedly arranged on the inner peripheral side of the coil 15 to strengthen the magnetic force. Furthermore, a rotor 17 is arranged inside the stator 16. The rotor 17 is rotatably supported by a step 18 formed in the casing of the step motor 9 via a rolling bearing 19. And in the center of this rotor 17,
Female threaded hole 2 passing through this rotor 17 in the axial direction
0, and the rod 2 is disposed and supported so as to be movable only in the axial direction on the extension line of the control rack 8.
A male thread 22 formed on the outer circumferential side of 1 is engaged with the female threaded hole 20.

The left end of the rod 21 in FIG. 2 is connected to the end of the control rack 8 via a connecting plate 23. The right end of the control rack 8 is guided by a guide hole 25 of a guide plate 24 fixed to the casing of the fuel injection pump 2, as shown in FIG. Furthermore, since the guide hole 25 is L-shaped, the control rack 8 is prevented from rotating by the guide plate 24. Further, an iron core 26 is fixed to the rod 21, and this iron core 26 is inserted into the differential transformer 14. Therefore, Rod 21
The amount of movement is detected by this differential transformer 14. In addition, the right end side of the rod 21 in FIG. 2 has a non-circular cross section as shown in FIG.
The rod 21 is engaged with a guide hole 28 of a guide plate 24 fixed to the end of the casing of the step motor 9, so that although the rod 21 can slide in the axial direction, it cannot rotate in the rotation direction. being made incapable of doing so. A compression coil spring 30 is interposed between the spring receiver 29 of the rod 21 and the casing of the step motor 9 to eliminate backlash, and this spring 30 causes the rod 21 to move toward the left in FIG. is being pushed. Further, the right end guide plate 27 of the step motor 9 is covered by a dust cover 31.

In the above configuration, when a pulse-like control signal is supplied from the microcomputer 10 to the step motor 9, the coil 15 of the motor 9 is sequentially excited, thereby causing the rotor 17 to rotate intermittently. It turns out. Then, the rod 21 having the male thread 22 that engages with the female threaded hole 20 of the rotor 17 moves in the axial direction because its rotation is prevented by the guide hole 28 of the guide plate 27. That is, when the step motor 9 rotates, the rod 21 moves in the axial direction in response, and the control rack 8 is moved to the right or left in FIG. 2 via the connecting plate 23. Then control rack 8
rotates the barrel 2 of each pump unit 6, thereby adjusting the amount of fuel supplied.

As described above, according to the fuel supply system of this embodiment, the rotational motion of the step motor 9 is extracted as a linear motion of the rod 21, and the control rack 8 is thereby moved. Therefore, it is possible to electronically control the fuel injection pump 2 with a very simple configuration. Further, according to the device of this embodiment, the amount of movement of the control rack 8 per one pulse supplied from the microcomputer 10 is determined not only by the rotation angle per one step of the step motor 9 but also by the pitch of the screw 22 of the rod 21. Therefore, the accuracy can be freely selected by changing the pitch of the pulse motor 9 and the screw 22, and the rack 8 can be controlled with high precision. It becomes possible. Furthermore, since backlash is removed from the rod 21 by a backlash removing spring 30, the accuracy is not reduced by backlash between the screw 22 and the screw hole 20. Furthermore, since the female screw hole 20 is formed through the center of the rotor 17 and the male screw 22 of the rod is engaged with this male screw hole 20, the female screw hole 20 can be connected to the female screw hole 20 without increasing the size of the step motor 9. The male screw 22 can be expanded to a dimension corresponding to the thickness (width) of the rotor 17, and stable driving force can be obtained, and the control rack 8 and rod 21 can be expanded to a dimension corresponding to the thickness (width) of the rotor 17.
Since the two are connected via the connecting plate 23, mutual transmission of heat, vibration, etc. between the two can be reduced.

As described above, the present invention drives a step motor in response to a control signal from an electronic control device, and moves in the axial direction a rod having a male screw that engages with a female screw hole passing through the center of the rotor of the step motor. The fuel is supplied in accordance with this movement stroke. Therefore, the accuracy can be freely selected by changing the rotation angle per step of the step motor and the pitch of the thread of the rod, and it is also possible to control the fuel supply with high precision.
In addition, the rotation of the step motor is directly converted into linear motion inside the step motor by a rod having a male screw that engages with a female screw hole passing through the center of the rotor of the step motor. Since the control device is connected via a .sub.2 to suppress mutual transmission of heat or vibration between the two, the control device can be constructed in a compact and simple manner, and the number of parts can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing a fuel supply control device for a diesel engine according to an embodiment of the present invention;
2 is a sectional view of a main part showing a control device for a fuel injection pump of this engine, FIG. 3 is a sectional view taken along the line .about. in FIG. 2, and FIG. 4 is a sectional view taken along the line .about. in FIG. In addition, in the symbols used in the drawings, 2...Fuel injection pump, 8...Control rack, 9...Step motor, 10...Microcomputer,
17... Rotor, 20... Female threaded hole, 21... Rod, 22... Male thread, 30... Compression coil spring.

Claims (1)

[Claims] 1. In a device in which the movement of a control rack of a fuel injection pump is controlled by a step motor, a female threaded hole is formed through the center of the rotor of the step motor, and a rod provided with a male thread that engages with this female threaded hole is attached to the control rack. A fuel supply control device characterized in that the rod is disposed so as to be movable in the axial direction only on an extension of the rod, and one end of the rod is connected to the end of the control rack via a connecting plate.