JPS593161A - Method of controlling fuel injection device - Google Patents

Abstract

PURPOSE:To arbitrarily regulate injection timing and injection period with the same injection amount, by providing an accumulate piston and a pressure control valve for varying a set pressure, which are communicated with a pressure chamber to be pressurized by a plunger designed to be reciprocatable and rotable. CONSTITUTION:A fuel injection pump acts to pressurize fuel sucked from a fuel chamber 11 through a suction hole 2 into a pressure chamber 4 by the reciprocating and rotating motions of a plunger 1, and to pump the fuel through an injection pipe 31 to a fuel injection nozzle 30. In connection with this, there are provided in a cylinder portion 10 including the pressure chamber 4 means 200 for controlling maximum pressure in the pressure chamber 4 and means 100 for controlling injection start timing. The means 100 is constituted in such a manner that the amount of accumulated high pressure fuel may be regulated by controlling a stroke of an accumulate piston 101 until a control surface 101a of the piston 101 closes a control hole 106. On the other hand, the means 200 is constituted in such a manner that a biasing force to a pressure regulating valve 201 may be variably controlled to control an upper limit of the pressure in the pressure chamber 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fuel injection device for an internal combustion engine, and more particularly, to a method for controlling the injection waveform, that is, the injection rate and injection timing, which affects combustion in the internal combustion engine.

Conventionally, almost no method has been proposed for arbitrarily controlling the injection rate or injection timing depending on the operating state of the internal combustion engine. In particular, small-sized fuel injection devices such as unit injectors generally do not have a mechanism that can control injection timing. Controlling the injection waveform means indirectly controlling combustion (2), so in diesel engines, especially direct injection diesel engines, where the performance changes greatly depending on the injection method, it is important to control the injection waveform. There were strong demands regarding the control method.

The present invention has been made in order to meet the above-mentioned needs, and the injection start timing and injection amount can be controlled by adjusting the injection start timing and injection amount to the Akiem rate piston
By controlling the rotation of the engine 01 and the plunger 1, the engine is controlled arbitrarily according to the operating conditions of the internal combustion engine, and the purpose is to improve fuel efficiency, purify exhaust gas, reduce noise, and improve drivability.

First, a first embodiment of the present invention will be described.

1 to 4 relate to a first embodiment of the present invention.

FIG. 1 shows a system diagram of the entire fuel injection system, and 1 is a plunger of an injection pump, which is slidably and rotatably fitted in an oil-tight manner to a cylinder portion 10. A vertical groove 6 along the central axis of the plunger 1 and a radial hole 7 communicating with the vertical groove 6 are bored in the plunger, and an annular groove 5 is provided at the outer peripheral end of the radial hole 7. One end surface of the slanted surface (3) is an open surface 1a. Further, a flat portion 8 having a width across two surfaces is provided for controlling the rotation of the plunger roll.

The cylinder portion 10 includes a maximum pressure control device 2 in the pressurizing chamber 4.
00 and an injection start timing control device 1 (10) are installed. 2 is a suction hole for supplying fuel from the fuel chamber 11 to the pressurizing chamber 4, and the check valve 12 acts to supply fuel from the fuel chamber 11. Only the inflow into the pressurizing chamber 4 is allowed. Numeral 3 is a spill hole, which is used to control the end timing of pressure feeding of fuel from the pressurizing chamber 4 to the injection pipe 31. When communicating with the fuel chamber 11 via the hole 6, the radial hole 7, the annular groove 5, and the spill hole 3, the fuel pumping is interrupted.

The structure of the injection start timing control device 100 will be described. Reference numeral 101 is an accumulation piston, and the outer peripheral portion of the accumulation piston 101 is fitted into the cylinder portion 10 in an oil-tight manner so as to be slidable and rotatable. Accumulate piston 101 is biased to the right in the figure by a spring 105.

Accumulate piston 101 has an inclined control surface 101
It has a. Reference numeral 106 is a control hole that communicates the oil (4) closed chamber 109 with the fuel chamber 11. Reference numeral 103 denotes a suction hole, which only allows inflow from the fuel chamber 11 into the oil-tight chamber 109 by the action of a check valve 104.

To explain the structure of the maximum pressure control device 200, 2
01 is a pressure control valve, which is biased to the left in the figure by a spring 205. 204 is a control member for variably controlling the set load of the spring 205, and is provided with a threaded portion 206. 203 is a leak hole that communicates the leak chamber 209 and the fuel chamber 11.

Further, 102 and 202 are communication holes for guiding the fuel in the pressurizing chamber 4 to the injection start timing control device 100 and the maximum pressure control device 200, respectively. The pressurizing chamber 4 is connected to a fuel injection nozzle 30 via an injection pipe 31.

The operation will be explained with reference to FIGS. 1 to 4.

The plunger 1 performs reciprocating motion in the vertical direction as shown in FIG.

During the suction stroke in which the plunger 1 moves downward, the fuel in the fuel chamber 11 is pressurized through the spill hole 3, (5) annular groove 5, radial hole 7, vertical hole 6, or through the suction hole 2. Sent to room 4. After the plunger l is further lowered in the state shown in the figure and the control surface la closes the spill hole 3, fuel is sucked into the pressurizing chamber 4 only through the suction hole 2.

When the plunger 1 reaches its lowest point and a compression stroke is started by raising the plunger 1, the pressure within the pressurizing chamber 4 begins to rise. Then, the biasing force of the accumulation piston 101 in the leftward direction due to the pressure in the pressurizing chamber 4 increases and overcomes the biasing force of the spring 105 in the oil-tight chamber 109.
The accumulation piston 101 begins to move leftward, and at the position where the control surface 101a closes the upper end opening of the control hole 106, the inside of the oil-tight chamber 109 becomes hydraulically locked, and the movement of the accumulation piston 101 stops.

The pressure in the pressurizing chamber 4 is suppressed from increasing at the same time as the accumulation piston 101 starts moving. This is because the fuel pumped by the plunger 1 is used to replenish the space created at the tip of the accumulating piston 101 by the movement of the accumulating piston 101.

When the movement of the accumulation piston 101 stops, the pressure inside the pressurizing chamber 4 starts to rise again, and when it reaches the valve opening pressure of the fuel injection nozzle 30, injection starts.

When the pressure in the pressurizing chamber 4 further increases and the urging force on the pressure control valve 201 overcomes the urging force on the spring 205, the fuel in the pressurizing chamber 4 passes through the leak hole 203 and returns to the fuel chamber 11. As a result, the pressure inside the pressurizing chamber 4 will no longer rise.

When the plunger 1 further rises, the spill hole 3 is opened as shown in FIG. 1, and the pressurizing chamber 4 and the fuel chamber 11 communicate with each other, the pressure inside the pressurizing chamber 4 rapidly decreases. Communication hole 2
The right end face opening of 02 is closed by a pressure control valve 201,
Next, the injection hole of the fuel injection nozzle 30 is closed, and the next accumulation piston 101 is returned to the right end stop position by the urging force of the spray young 105. At this time, oil-tight room 109
Fuel is introduced into the fuel chamber 11 through an intake hole 103 and a control hole 106.

(7) Then, when the plunger 1 finishes rising, the compression stroke ends, each part returns to its initial state, and the (2) cycle ends, and this cycle is repeated thereafter.

A model diagram of the pressure increase in the pressurizing chamber 4 during the above compression stroke and a model diagram of the injection rate waveform at that time are shown in FIG. 3, respectively. Compression is started at ■ in Figure 3, ■ is the start of movement of the accumulation piston 101, ■ is the end of movement of the accumulate piston 101, ■ is the start of injection from the nozzle 30, and ■ is the start of operation of the pressure control valve 201. , ■ indicates when the spill hole 3 is in communication, ■ indicates the end of jetting from the nozzle 30, and ■ indicates the time when the initial state is returned. The slope of ■−■, ■→■, is determined by the oil feed rate of the pump, and the slope of ■→■ is determined by the spring 105.
It is determined by the spring constant of , and the slope of ■→■ is determined by subtracting the nozzle injection rate from the pump oil delivery rate. Pa is the set load of the spring 105, Pv is the pressure when balancing the set load of the spring 205, and Pn
is the nozzle opening pressure. The broken line in FIG. 3 shows the state when the re-equipment is not activated, the one-dot chain line shows the state when only the accumulation piston 101 is operated, and the two-dot chain line shows the state when only the pressure control valve 201 is operated.

In the above cycle, only the maximum pressure control bag W2O0 is operated to rotate the control member 204, and the pressure control valve 20
By changing the set pressure pv of 1, Fig. 2+a)
The maximum injection rate can be regulated as follows.

In addition, when only the injection start timing control device 100 is operated to control the rotation of the accumulation rate piston 101, a pressurizing chamber is formed in the space at the tip of the accumulation piston 101 before the control surface 101a closes the upper end of the control hole 106. The amount of fuel flowing in from 4, that is, the amount of fuel flowing from control surface 10
Since 1a is an inclined surface, it is variably controlled. When the accumulation amount is small, the period from ■ to ■ in FIG. 3 becomes shorter, and the time point at ■ becomes earlier than before. Therefore, by controlling the rotation of the accumulation piston 101,
As shown in FIG. 2 (bl), the injection start timing can be controlled.

(9) Furthermore, by controlling the rotation of the plunger 1, it is possible to variably control the timing at which the control surface 1a, which is an inclined surface, opens the spill hole 3, that is, the time point (■) in FIG.
By controlling the rotation of the plunger 1 as shown in FIG. tc, the injection end point can be controlled.

The set pressure Pv- of the pressure control valve 201, and the accumulation rate amount Ac- by the accumulation piston 101.

By simultaneously controlling the rotation control angle θ of the plunger l, it is possible to create an optimal injection waveform according to various engine conditions.

Note that since the integral value of the injection rate waveform in FIG. 2, that is, the area of the waveform, indicates the injection amount, the injection amount can be adjusted using any of the control mechanisms (a), (bl, and (C1)). .

Therefore, as shown in Fig. 4, while the injection amount shown by the area of the shaded area is kept constant, the injection rate waveform with a slow injection timing as shown in A in Fig. 4 can be changed as shown in B in Fig. 4. The injection timing can be advanced without changing the injection waveform, or the injection period can be changed without changing the injection timing (10), as shown from B in FIG. 4 to C in FIG. 4. Note that 0 in FIG. 4 is the maximum possible injection amount, and corresponds to the cases of Pv maximum, Ac=Q, and θ maximum in FIG. 2. A is a waveform when the accumulation piston is activated from the state of O to delay the injection start time, B is a waveform when the injection start time is advanced by the accumulation piston from the state of A, and the spill hole opening time is also advanced. is the waveform when the injection start time is advanced from state B, the spill hole opening time is delayed, and the pressure control valve is activated to lower the set pressure of the pressure control valve, and the shaded areas of A, B, and C are They are from the same time.

As shown in the above explanation, by using the present invention, the injection timing, injection period, etc. can be arbitrarily adjusted with the same injection amount.

Next, a second embodiment of the present invention will be described.

5 to 8 relate to the second embodiment of the present invention, and show an example used in a unit injector. FIG. 6 is a sectional view taken along the line ■-■ in FIG. FIG. 8 is a cross-sectional view showing the detailed structure of the maximum pressure control device 200, and FIG. 8 is a cross-sectional view showing the detailed structure of the injection start timing control device 100.

A needle 32 is provided within the nozzle body 40 so as to be reciprocatable in the axial direction thereof. Reference numeral 21 is a holder body which is screwed into the threaded portion of the retaining nut 20, and is fixedly tightened with the nozzle body 40 sandwiched therebetween.

The spring 34 is in contact with the spring seat 33, and functions to urge the top of the needle 32 in the valve-closing direction against the valve-opening force of the needle 32 due to fuel pressure. The holder body 21 is provided with a discharge hole 35 for pumping the injected fuel. The threaded part of the body 22 is screwed into the holder body 21, and the cylinder 1o
The tightening is fixed by sandwiching it. Further, an injection start timing control device 100 and a maximum pressure control device 200 are screwed into the body 22.

The control cylinder 19 and the plunger 1 are slidably and rotatably fitted in an oil-tight manner, and the control cylinder 19 is fitted to the body 2.
Both are rotatably fitted in an oil-tight manner. cylinder 1
0 is provided with a communication hole 202a that communicates with the pressurizing chamber 4,
It is connected to the communication hole 202C via the communication hole 202b of the body 22.

Similarly, the communication hole 102C is the communication hole 102a or 1 (not shown).
It communicates with the pressurizing chamber 4 via 02b.

The fuel sent from the feed pump (not shown) is
The fuel is sent to the pressurizing chamber 4 via the fuel hole 13 and the suction hole 2.

Further, the fuel hole 13 has an annular groove 14, leak holes 203a, 203
It communicates with the leak chamber 209 via the low pressure hole 110a.
, 110b, the suction hole 103, and the control hole 106 to communicate with the oil-tight chamber 109. The cam plate 23 reciprocates up and down by the rotational movement of the cam 17 in synchronization with an engine (not shown). The pin 15 is for connecting the cam plate 23 and the plunger 1. The cam plate 23 is urged by the spring 16 so as to be in constant contact with the cam.

In the example of FIG. 5, instead of controlling the rotation of the plunger 1,
Rotation of the plunger 1 is restricted by a flat portion 8 having a width across flats,
A mechanism for controlling the rotation of the hole 3 (13) drilled in the control cylinder 19 is used, and the control surface 1a of the plunger 1 has a spiral shape. control cylinder 1
The control method 9 is performed by the rank gear 18. The rack gear 18 may be controlled mechanically or hydraulically.

In the first embodiment shown in FIG. 1, the set pressure of the pressure control valve 201 is controlled by controlling the rotation of the control member 204, but in this second embodiment, the set pressure of the pressure control valve 201 is controlled by controlling the rotation of the control member 204. The center load of the spring 205 is roughly adjusted to the same level as the pressure, and delicate adjustments are made by controlling the hydraulic pressure P2 to the hydraulic control chamber 207. Therefore, the biasing force of the pressure control valve 201 in the valve opening direction is (biasing force of the spring 205)
+ (biasing force due to the hydraulic pressure in the hydraulic control chamber 207).

Therefore, when the control oil pressure P2 is increased, the pressure control valve 201
The set pressure increases, and as P2 decreases, the set pressure decreases.

In addition, in the first embodiment shown in FIG. 1, the accumulation piston amount was controlled by rotating the accumulation piston 101, but (14) in this second embodiment, the control hole 106 was slid. A control mechanism was used. For this reason, the pressure-controlled hydraulic pressure PI
is guided to the hydraulic control chamber 107 via the hydraulic hole 10B, and the sleeve 112 is brought to rest at a position where the biasing force from the spring I11 to the right in the figure and the biasing force due to the hydraulic pressure P1 are balanced. Accumulating piston 101 can be moved to the right to a position where its control surface 101a closes control hole 106. The control hole 106 communicates with the low pressure hole 110b via a communication groove 113 cut in the sleeve 112 and a chamber of the spring 111.

9 to 11 show other embodiments of the injection start timing control device 100, and FIG. 10 is a sectional view taken along plane I-1 in FIG. 9.

In the embodiment shown in FIG. 9, the relative distance between the control surface 101a and the control hole 106 is controlled by sliding the sleeve l12 as shown in FIG. 8, but in FIG. The relative distance between the control hole 106 and the control surface 101a is controlled by rotating the control cylinder 121 provided with a hole. The control cylinder 121 is rotated by balancing the forces of the control oil pressure P1 and the torsion coil spring 124, and this operation will be explained with reference to FIGS. 9 and 10. The hydraulic hole 108 communicates with a high pressure chamber 126,
The high pressure chamber 126 has an end surface 128a, a spacer 123, and an end surface 1.
29 and a control cylinder 121. Spacer 1
23 and the control cylinder 121 have protrusions 123a, 121a for partitioning a room, and although the spacer 123 is fixed, the control cylinder 121 is fitted in an oil-tight manner so as to be rotatable. A low pressure chamber 127 communicates with the low pressure hole 110b via a communication hole 128 and the like. 124 is a torsion coil spring whose right end is fixed to the cap 119 and whose left end is fixed to the control cylinder 121;
the direction in which the volume of the high pressure chamber 126 decreases, that is, the first
It is biased in the clockwise rotation direction in Figure 0. Control pressure P
As I increases, the pressure inside the high pressure chamber 126 increases, and the first
The control cylinder 121 rotates to a position where the biasing force applied to the control cylinder 121 in the counterclockwise rotation direction shown in Figure O is balanced with the biasing force of the torsion coil spring 124.

Further, the accumulation piston 101 can freely slide in the left-right direction, but it can be moved freely by a steel ball 122 that is fitted into a groove cut on the outer periphery of the accumulation piston 101 along the central axis direction. Rotation is regulated. Therefore, by rotating the control cylinder 121, the amount of movement of the accumulation piston 101 until the control surface 101a, which is an inclined surface, closes the control hole 106 can be changed.

FIG. 11 shows the control surface 101a with the control hole 106 fixed.
This is an embodiment in which an Achiem rate piston 101 having a diameter is rotated by a step motor 130.

The tip of the shaft of the step motor 130 has a width across flats of 130a.
The rotary torque of the temp motor 130 is transmitted to the accumulate piston 101 whose rotation relative to the pressure plate 132 is restricted. here,
Achiem rate piston 101 as shown by Pa in Fig. 3
The set pressure of (17) is considerably smaller than the valve opening pressure Pn of the valve, so that the accumulation piston 101 can easily operate.
05 can be made quite small, and the rotational torque can be small! ! ! This means that the mechanism shown in FIG. 811 can be rotated by the step motor 130. In addition, in FIGS. 8 and 9, parts that are not operating parts are rotated or slid, so it is possible to control them with a considerably small force.

Furthermore, in the embodiment shown in FIG. 11, the step motor 13
0 may be replaced by a DC motor or a rotary solenoid, or a mechanism rotated by controlled oil pressure as shown in the embodiment of FIG. 9 may be used. In short, the control surface 101a of the accumulate piston 101 and the control hole 10
Any means may be used as long as it controls the relative distance in the axial direction with respect to 6.

Similarly, any mechanism for closing the spill hole 3 with the control surface 1a may be used as long as it controls the relative distance in the axial direction between the spill hole 3 and the control surface 1a.

As explained in detail above, the present invention provides an accumulation piston 10 at a position communicating with the pressurizing chamber 4 (18) of the pump.
1 and a pressure control valve 201, the accumulation piston 101 can variably control the accumulation amount, and the pressure control valve 201 can variably control the set pressure.
By controlling 01, the injection rate Q can be adjusted as shown in Fig. 2 (a).
By controlling the accumulation piston 101 which is biased by a weak spring 105, the injection start timing and injection amount can be controlled on the ladder shown in FIG. This control has the effect of controlling the injection end timing and injection amount as shown in Fig. 2 (C1).In addition, the three control variables of the set pressure Pv1 accumulation amount A c- and the plunge 10-rotation control angle θ can be controlled. Simultaneous system control has the advantage that a wide variety of injection waveforms can be set.

[Brief explanation of drawings]

1 to 4 relate to the first embodiment of the present invention, in which FIG. 1 is an overall system diagram, FIG. 2 is a fuel injection characteristic diagram showing the fuel injection rate that changes over time, and FIG. 4 and 4 are characteristic diagrams showing the pressure in the pressurizing chamber 4 and the fuel injection rate that change as the crank angle changes (or as time passes). 5 to 8 relate to the second embodiment of the present invention, in which FIG. 5 is a sectional view along the central axis of the fuel injection device, and FIG.
The figure is the ■-■ sectional view of Figure 5, and the figure 7 is the maximum pressure control bag w.
A sectional view showing the detailed structure of 200, Figure 8 is the injection start timing control bag! 100 is a cross-sectional view showing the detailed structure of FIG. 9 to 11 show other embodiments of the injection start timing control device 100, and FIG. 9 shows the injection start timing control device 10.
10 is a sectional view along the I-I plane of FIG. 9, and FIG. 11 is a different type of embodiment from FIG. 9. IO...Cylinder part, 1...Plunger, la...
- Control surface, 201... Pressure control valve, 4... Pressurization chamber,
1o1...accumulate piston, 101a...
control surface. 106... Control hole, 109... Oil tight chamber, 30...
Fuel injection nozzle, 3...spill hole. Representative Patent Attorney Takashi Okabe

Claims (1)

[Scope of Claims] In a fuel injection device that reciprocates a plunger (1) inserted into a cylinder portion (10) to pressure feed fuel, (1) variably controls the urging force to a pressure control valve (201). (ii) control of the achievable rate piston (101); Surface (101a) and control hole (106)
By variably controlling the stroke between the oil-tight chamber (109) and the opening on the inner circumferential surface of the oil-tight chamber (109), the amount of accumulated fuel is accumulated at a pressure lower than the valve opening pressure of the fuel injection nozzle (30). A method of controlling and adjusting the fuel injection start timing and fuel injection amount, (iii) the control surface (1a) of the plunger (1) and the surface (1)
1) A method in which the stroke between the bill hole (3) and the opening to the inner circumference of the cylinder is variably controlled to variably control the timing at which the pressurized fuel is released, thereby adjusting the fuel injection end timing and fuel injection amount. A fuel injection device characterized in that the fuel injection characteristics such as fuel injection start timing, fuel injection rate, fuel injection end timing, etc. are set and controlled by using the method of (i) or iii) above alone or in combination. Control method.