JPS6337257B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge amount adjusting device for adjusting the fuel discharge amount of a fuel injection pump in a diesel engine or the like.

As a conventional fuel injection pump discharge amount adjusting device, there is a device as shown in FIG. 1A and FIG.

That is, this fuel injection pump 1 has a cam disc 2 connected to a drive shaft of an engine.
The plunger 3 is configured to perform reciprocating movement and rotational movement in the axial direction by the rotation of 5, fuel is sucked into the operating space 6 of the plunger 3.

Next, in the discharge stroke, the plunger 3 moves to the right to pressurize the sucked fuel, and the pressurized fuel passes through the vertical passage 7, and when the discharge vertical groove 8 aligns with the discharge passage 9, a check is made. The fuel is discharged through the valve 10 to the injection valve (not shown) of the corresponding cylinder.

In this case, the discharge of the injection pump is completed by releasing the fuel in the operating space 6 of the pump to the space inside the pump outer casing via the fuel release passage 11 provided in the plunger 3. The timing to open the passage 11 is determined by a cylindrical valve member (sleeve valve) slidably fitted on the outer periphery of the plunger 3.
12, thereby adjusting the amount of fuel discharged.

In this conventional example, the mechanism for operating the valve member 12 includes an electromagnet having two coils 14 and 15 wound around an iron core 13 having a cylindrical gap, and an outer casing connected to the rotating shaft 16 within the gap. Part 17
A torque motor consisting of a rotating permanent magnet 18 rotatably supported by a rotary magnet 18 is used.

A fan-shaped piece 19 is eccentrically attached to the lower end of the rotating shaft 16 of the torque motor, and a spherical engagement piece 20 is fixed eccentrically from the center axis of the fan-shaped piece 19.
is fitted in the hole 21 of the valve member 12, and is adapted to transmit the rotational movement of the rotating permanent magnet 18 to the valve member 12, thereby displacing it in the axial direction.

The electromagnetic coils 14 , 15 are connected via an amplifier 22 to an output of a control device 23 . This control device 23 includes, as operating parameters (operating conditions) of the meat combustion engine, for example, an engine rotation speed signal from a rotation speed sensor 25, an accelerator pedal position signal from an oscillator 26, and other intake pipe negative pressure (not shown). , a signal related to engine temperature or ambient temperature, etc. is given as an input, and a current corresponding to these operating parameters is supplied via an amplifier 22, and the rotating permanent magnet 18 is rotated with an operating force corresponding to this. .

The rotation sensor 25 is arranged opposite to a toothed disk 24 attached to the drive shaft of the engine, and generates a voltage proportional to the engine rotation speed from an induction coil 25b wound around a magnet 25a, and transmits it to the control device. 23.

Further, the position sensor 27 that generates a feedback signal for controlling the position of the valve member 12 converts the rotation of the rotating permanent magnet 18 into a linear displacement of the ferrite magnetic core 27c using a cam plate 29, a rod 27a, and a spring 27b. , 2 powered by the oscillator 28
The position of the valve member 12 is indirectly detected by the inductance coils 27d and 27e.

However, in such a conventional fuel injection pump discharge amount control device, a torque motor is used to displace the valve member 12, and the rotational force is transferred to the rotating shaft 16, the eccentric fan-shaped piece 19, the spherical engagement piece 20, etc. The mechanism is complicated, and mechanical errors occur between each member, making it impossible to perform highly accurate adjustment.

Furthermore, if the torque motor fails, the valve member 12 cannot be displaced, so there is a problem in that the amount of fuel discharged remains high, potentially causing the engine to run out of control.

Furthermore, for example, Utility Model Application No. 57-40658 and Utility Model Application No. 57
As seen in No. 8356, there are devices that use a solenoid to drive a valve member to control the fuel injection amount or injection timing, but these also depend on the balance between the driving force of the solenoid and the biasing force of the return spring. Since the valve member is driven through a mechanical coupling member, mechanical errors are likely to occur, and since feedback control is not performed, it is difficult to achieve highly responsive and highly accurate control.

The present invention has been made in view of the above points, and aims to reduce costs by simplifying the structure of the discharge amount adjusting device in a fuel injection pump as described above, and to improve feedback control by eliminating room for mechanical errors. The objective is to improve the drivability and exhaust performance of diesel engines by making them function effectively, improving responsiveness and adjustment accuracy, and always keeping the fuel injection amount at the optimum value, as well as improving safety.

Therefore, in the fuel injection pump discharge amount adjusting device according to the present invention, the above-mentioned cylindrical valve member (sleeve valve) for adjusting the discharge amount is configured by a cylindrical permanent magnet or integrally with a cylindrical permanent magnet. A pair of electromagnetic coils facing each other at a distance from each other around the outer periphery of the valve member, a position sensor that detects the displacement of the valve member without contact, and a target of the valve member in relation to the operating parameters (operating conditions) of the internal combustion engine. position and directly control the excitation current of the pair of electromagnetic coils according to the deviation between the target position and the actual position of the valve member detected by the position sensor, and also control the position of one of the pair of electromagnetic coils. A valve member drive control means is provided which excites the other electromagnetic coil and displaces the valve member even when the other electromagnetic coil fails.

Embodiments of the present invention will be described below with reference to FIG. 2 and subsequent figures.

FIG. 2 is a longitudinal sectional view of a discharge amount adjusting device portion of a fuel injection pump showing an embodiment of the present invention;
Portions corresponding to those in FIG.

In this embodiment, the sleeve valve 30, which is a cylindrical valve member that opens and closes the fuel relief passage 11 provided in the plunger 3, is connected to a cylindrical permanent magnet 3.
1, ring-shaped pole pieces 32a and 32b made of a magnetic material are fixed to both end faces of the plunger 3, and the plunger 3 is fitted around the outer periphery of the plunger 3 so as to be slidable in the axial direction.

The permanent magnet 31 of this sleeve valve 30 is magnetized, for example, so that the left pole piece 32a in the figure is the north pole and the right pole piece 32b is the south pole.

On the other hand, in order to displace the sleeve valve 30 from side to side, a pair of cylindrical electromagnetic coils 33 and 34 are provided on the outer periphery of the sleeve valve 30, facing each other at a distance, and the outer periphery serves both as a magnetic path and as protection for the coil. It is surrounded by an outer covering yoke 35, and the yoke 35 is fixed to the outer casing 17 with screws.

A sleeve valve 30 made of this permanent magnet 31,
A pair of left and right electromagnetic coils 33 and 34 constitute the main part of the discharge amount adjusting device.

Further, a magnetic stay 36 is fixedly attached to the pole piece 32a of the sleeve valve 30 and protrudes outward in the radial direction of the plunger 3, facing the tip thereof.
A position sensor 37, which is a magnetic sensor that detects the displacement of the sleeve valve 30 in a non-contact manner, is attached to a bracket 17b that is integrated with the outer casing 17.

The detection signal from this position sensor 36 is then used as a feedback signal. In addition, 38
is a plunger spring, and 39 is a spring receiving plate.

FIG. 3 is a block diagram showing a drive control circuit (valve member drive control means) of this discharge amount adjusting device.

41 is a high frequency generation circuit, and the first drive circuit 5
0 and a high frequency rectangular wave signal that operates the second drive circuit 51.

42 is a triangular wave generation circuit that outputs a triangular wave signal;
43 is a command circuit for outputting a target value signal for the sleeve valve 30, and 44 is a position detection circuit including the position sensor 37 shown in FIG. 2, which detects the actual sleeve valve position and outputs an actual value signal.

45 is a deviation amplification circuit, which outputs a deviation signal according to the deviation between the target value signal S _O from the command circuit 43 and the actual value signal S _F from the position detection circuit 44.

46 is a comparison circuit which compares the triangular wave signal from the triangular wave generation circuit 42 and the deviation signal from the deviation amplification circuit 45, and converts the deviation signal into a pulse signal having a pulse width corresponding to the magnitude of the deviation at a predetermined period. It acts as a converting pulse width modulation circuit.

47 is an AND circuit, which performs an AND operation between the output of the comparison circuit 46 and the high frequency rectangular wave signal from the high frequency generation circuit 41, and outputs a driving signal.

A comparison circuit 48 compares the target value signal S _O from the command circuit 43 with the actual value signal S _F from the position detection circuit 44 .

49 is a selection circuit, which selects the driving signal A from the AND circuit 47 according to the output from the comparison circuit 48.
is selectively applied to the first and second drive circuits 50 and 51 to control the direction of the excitation current flowing through the electromagnetic coils 33 and 34.

FIG. 4 is a circuit diagram showing a specific example of the selection circuit 49, the first and second drive circuits 50, 51, and the comparison circuit 48.

When the target value S _O is larger than the actual value S _F , the comparison circuit 48 sets the output D to a low level “L”, and the target value S _O
When is smaller than the actual value _SF , the output D is set to high level "H".

The selection circuit 49 is constituted by a changeover switch circuit consisting of a pair of analog switches whose on/off is reversely controlled, for example, by the output D of the comparison circuit 48, Drive signal A is switched to output line B or C and output.

The first drive circuit 50 includes transistors Tr ₁ and Tr ₂ ,
The second drive circuit 51 includes electromagnetic coils 33 and 3 connected in parallel by transistors Tr ₃ and Tr ₄ , respectively.
A bridge circuit is constructed so that an excitation current flows in the opposite direction to 4.

Next, the operation of this embodiment will be explained with reference also to FIGS. 5 and 6.

Now, the command circuit 43 determines the position of the sleeve valve 30 to provide the optimum fuel discharge amount according to the operating parameters (operating conditions) of the engine, such as engine speed, accelerator pedal position, intake pipe negative pressure, engine temperature, etc. When the target value is output, the sleeve valve 30 is in the initial state.
is at the left end position and the actual value signal S _F from the position detection circuit 44 is 0, so the output of the deviation amplification circuit 45 becomes large and the output D of the comparison circuit 48 becomes "L".
become.

In this case, the selection circuit 49 selects the driving signal A.
is output to the output line B, the transistors Tr ₁ and Tr ₂ of the first drive circuit 50 are turned on (actually, they are turned on and off repeatedly by high-frequency pulses), and the electromagnetic coil 3 is turned on.
3 and 34 respectively in the direction shown by the solid line arrow in FIG. 4, an S pole is generated at the adjacent portions and an N pole is generated at the outer end, as shown in FIG. 5A.

Thereby, the sleeve valve 30 receives a force so as to be displaced in the direction of arrow A, and moves to the right in the axial direction of the plunger 3. When the sleeve valve 30 reaches the target position, the actual value signal from the position detection circuit 44 matches the target value signal, so the deviation amplification circuit 44
5 becomes 0 and the drive signal A is no longer output, the selection circuit 49 no longer outputs the operating signal to the first and second drive circuits 50 and 51, and the exciting current flows through the electromagnetic coils 33 and 34. It disappears.

Conversely, if the sleeve valve 30 moves too far to the right in the figure than the target value, the actual value signal S _F from the position detection circuit 44 becomes larger than the target value signal S _O , and the output of the comparison circuit 48 becomes "H". Therefore, the selection circuit 49 outputs the driving signal A to the output line C according to the deviation.

Therefore, the transistor of the second drive circuit 51
Tr ₃ and Tr ₄ are turned on, and excitation currents are applied to the electromagnetic coils 33 and 34 in the directions shown by the dashed arrows in FIG. 4, respectively, and as shown in FIG. generates an S pole at the

Thereby, the sleeve valve 30 receives a force so as to be displaced in the direction of arrow B, and moves to the left in the axial direction of the plunger 3.

In this way, by controlling the position of the sleeve valve 30 so that it is always at the target value, the fuel discharge amount can be adjusted to an optimal amount with respect to the operating parameters of the engine.

By the way, during such a discharge amount adjustment operation, for example, as shown in FIG.
If the first electromagnetic coil 33 has a failure such as wire breakage while energizing the sleeve The valve 30 can be displaced in the direction of arrow B.

Furthermore, when the second electromagnetic coil 34 fails, the first electromagnetic coil 33 is excited with the polarity shown in FIG. can.

As shown in Fig. 5A, the electromagnetic coils 33, 34
Even if one of the electromagnetic coils 33, 34 is disconnected while energized, the sleeve valve 30 can be continuously displaced in the direction of arrow A using only the remaining electromagnetic coil.

In this way, when either one of the pair of electromagnetic coils 33, 34 fails, the sleeve valve 30 can be continuously displaced only by the other electromagnetic coil, so that excessive fuel continues to be discharged and the engine There is no fear that it will run out of control.

In addition, when one of the electromagnetic coils 33, 34 has a failure such as wire breakage, it is detected and the other electromagnetic coil is always energized as shown in FIG. Alternatively, the fuel escape passage 11 of No. 3 may be displaced in the direction of opening, and the discharge of fuel may be stopped.

FIG. 7 shows a sleeve valve according to another embodiment of the invention. This sleeve valve 30 has a cylindrical non-magnetic material 37 in the portion that directly slides into contact with the plunger 3,
A cylindrical permanent magnet 31 is integrally fitted on the outer periphery of the magnet,
Ring-shaped pole pieces 32a, 3 are provided on both end surfaces.
2b is fixed.

In this way, even if the plunger 3 is made of a magnetic material, a closed magnetic path will not be formed between the two poles of the permanent magnet 31, so the thrust force for displacing the sleeve valve 30 can be increased, and responsiveness can be improved.

FIG. 8 shows still another embodiment of the present invention, in which a compression coil spring 52 is interposed between the pole piece on the right side in the figure of the sleeve valve 30 and the plunger storage member 17a, and its elastic force is used to prevent the sleeve valve from sliding. Fuel relief passage 11 with valve 30 provided in plunger 3
The device is biased in the opening direction (to the left in the figure).

In this way, the pair of electromagnetic coils 33, 3
Even if both pumps 4 fail, the sleeve valve is displaced to the left by the biasing force of the spring 38, opening the fuel escape passage 11, allowing fuel to escape into the pump space and stopping the discharge.

As explained above, the fuel injection pump discharge amount adjusting device according to the present invention has a simple structure and low cost because the valve member for adjusting the discharge amount is directly displaced by the electromagnetic force generated by the permanent magnet and the electromagnetic coil. By reducing the amount of fuel and making the feedback control function effectively, adjustment accuracy and responsiveness can be improved, and the fuel injection amount of the diesel engine can always be kept at the optimum value, improving drivability and exhaust performance. Can be done.

Furthermore, even if one of the pair of electromagnetic coils fails, the excitation current can be passed through the other electromagnetic coil to control the valve member, which improves safety.

[Brief explanation of the drawing]

FIGS. 1A and 1B are a configuration diagram and a sectional view of a main part of a conventional fuel injection pump discharge amount adjusting device.
FIG. 2 is a vertical sectional view of a discharge amount adjusting device portion of a fuel injection pump showing an embodiment of the present invention, and FIG. 3 is a block diagram showing a drive control circuit thereof.
FIG. 4 is a circuit diagram showing a specific example of the main part thereof, and FIGS. 5 and 6 are diagrams showing the excitation polarity of the electromagnetic coils 33 and 34 and the displacement direction of the sleeve valve 30 for explaining the operation. It is an explanatory diagram showing a relationship. FIG. 7 is a sectional view showing a sleeve valve according to another embodiment of the invention. FIG. 8 is a sectional view similar to FIG. 2 showing still another embodiment of the invention. 2...Cam disc, 3...Plunger, 11
...Fuel escape passage, 17...Outer casing, 30...
Sleeve valve (valve member), 31...Permanent magnet, 33,
34... Electromagnetic coil, 35... Yoke, 37...
position sensor.

Claims (1)

[Scope of Claims] 1. Displacing a cylindrical valve member provided in a plunger of a fuel injection pump that closes a fuel relief passage in the axial direction of the plunger, thereby closing the fuel relief passage during the fuel discharge stroke of the plunger. In the discharge amount adjusting device that adjusts the discharge amount of fuel by changing the opening timing, the valve member is constituted by a cylindrical permanent magnet or integrally with the cylindrical permanent magnet, and the valve member is arranged at intervals around the outer periphery of the valve member. a pair of electromagnetic coils facing each other,
A position sensor detects the displacement of the valve member in a non-contact manner, and a target position of the valve member is determined in relation to operating parameters of the internal combustion engine, and an excitation current of the electromagnetic coil is set using the target position and the position sensor. The position of the valve member is directly controlled by changing the position according to the deviation from the actual position of the valve member detected by the sensor, and even when one of the pair of electromagnetic coils fails, the other electromagnetic coil is energized. A discharge amount adjusting device for a fuel injection pump, comprising: valve member drive control means for displacing the valve member. 2. The discharge amount adjusting device for a fuel injection pump according to claim 1, wherein the valve member is formed by integrally fitting a cylindrical permanent magnet to the outer periphery of a cylindrical non-magnetic material. 3 between the valve member and the plunger storage member,
3. The discharge amount adjusting device for a fuel injection pump according to claim 1, wherein a spring is interposed to urge the valve member in a direction to open a fuel escape passage provided in the plunger.