JPH0754731A - Accumulator-type fuel injection equipment - Google Patents

Abstract

PURPOSE:To keep the pressure of a plurality of accumulators with high precision and evenness and to prevent the injection pressure wave from affecting the subsequent injection, in an accumulator-type fuel injection equipment. CONSTITUTION:A plunger 31 of a fuel injection pump 12 is moved in reciprocating and sliding motions in order to increase pressure on a pump chamber 32, so that the fuel in this pump chamber 32 is sent by pressure from a discharge ports 13, 14 to first and second accumulators 20, 21 via fuel passages 16, 17. The fuel accumulated in the first and second accumulators 20, 21 is injected from a prescribed injector to a corresponding cylinder, according to opening/ closing of a control valve. Because the injectors of the cylinders, whose injection orders are not sequential, are connected separately to the first accumulator 20 or to the second accumulator 21, the injection takes place alternately from the first accumulator 20 or from the second accumulator 21. Although the pressure wave, which is produced after the injection of each injector, passage the first accumulator 20 or the second accumulator 21, since the pressure wave is stopped by discharge valves 61, 62, the pressure wave is prevented from propagating from an accumulator to another accumulator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a multi-cylinder engine in which high pressure fuel stored in a pressure accumulator is injected from a plurality of injectors.

[0002]

2. Description of the Related Art A so-called common rail fuel injection system for supplying high pressure fuel stored in a pressure accumulating chamber to each injector as a means for supplying high pressure fuel to a plurality of injectors provided corresponding to a plurality of cylinders of a multi-cylinder engine. It has been known. The common rail fuel injection device accumulates the high pressure fuel pumped from the high pressure injection pump in a pressure accumulating chamber of the common rail, and supplies the high pressure fuel to an injector attached to the tip of each pipe by a plurality of pipes branched from the pressure accumulating chamber. The injection timing and injection amount of the fuel injected from the injector are controlled by a solenoid valve attached to the injector inlet based on a command from the control device. Here, a conventional injection pump for sending high-pressure fuel to a pressure accumulating chamber pressurizes the pump chamber by reciprocally sliding a plunger in a cylinder, as shown in, for example, Japanese Patent Laid-Open No. 4-159451. The high-pressure fuel of is sent under pressure from the discharge port to the accumulator chamber.

[0003]

Generally, when a plurality of injectors are divided into a plurality of groups and a pressure accumulating chamber is provided for each of the divided groups, in order to eliminate the non-uniformity of the injection amount of the plurality of injectors, The pressure in each accumulator must be uniform. To equalize the pressure of multiple accumulators, connect each accumulator with a pipe,
A method is proposed in which one cylinder of an injection pump is assigned to each pressure accumulator and each pump cylinder is controlled separately.

Japanese Patent Laid-Open No. 3-18526, which is an example of the above
In the pressure-accumulation fuel injection device disclosed in Japanese Patent Publication No. 1, the entire cylinder is divided into a plurality of groups each having injectors of the same cylinder whose injection order is not adjacent to each other, and a pressure accumulator is provided for each divided group. By supplying high-pressure fuel from the injection pump to the plurality of pressure accumulators, the plurality of pressure accumulators are maintained at a high pressure and the injection pressure of the injector is prevented from decreasing.

However, according to such a conventional pressure-accumulation type fuel injection device, in the case where each pressure accumulator is connected by the connecting pipe, (1) the mounting space of the connecting pipe is required, so that the mountability on the engine is deteriorated. Let me also
(2) Pressure pulsation occurs in the pressure accumulator due to the pressure wave generated after the injection from the injector, and this pressure pulsation propagates through the connecting pipe to the other pressure accumulator, and the injection amount of the next injection is uneven. To In the case where one cylinder of each injection pump is connected to each pressure accumulator, there is a problem that it is difficult to keep the pressure of each pressure accumulator uniform due to variation (nonuniformity) in performance of each cylinder of the injection pump.

The present invention has been made in order to solve such a problem, and eliminates a connecting pipe for connecting divided pressure accumulators, and highly accurately controls the pressures of a plurality of pressure accumulators in one cylinder of an injection pump. It is an object of the present invention to provide a pressure-accumulation fuel injection device that can be uniformly held.

[0007]

The pressure-accumulation fuel injection system of the present invention for solving the above-mentioned problems is composed of a plurality of injectors provided for each cylinder of a multi-cylinder engine, and a plurality of injectors whose injection order is not adjacent to each other. The entire cylinder is divided into a plurality of groups each including one injector, and a plurality of pressure accumulators provided for each of the divided groups are provided, and the high-pressure fuel accumulated in the plurality of pressure accumulators is predetermined from a corresponding injector. In the fuel injection device for injecting and supplying the fuel at the timing of, a plurality of injection pumps for pumping the fuel in the pump chamber from the discharge port and a plurality of branches branched from the pump chamber or a passage communicating with the pump chamber and communicating with the plurality of pressure accumulators are provided. A check valve provided in the fuel passage and the plurality of fuel passages for preventing a pressure wave generated after the injection of the injector from being transmitted from the corresponding pressure accumulator to another pressure accumulator. , Characterized by comprising a.

[0008]

According to the structure of the pressure-accumulation fuel injection device of the present invention,
The injectors whose injection order is not adjacent to each other are grouped in advance, and high-pressure fuel is supplied to the corresponding injectors from the pressure accumulators provided for each group. Then, fuel is pressure-fed to a plurality of pressure accumulators from one or two or more discharge ports corresponding to one cylinder of the injection pump via a check valve, and the fuel is supplied to the corresponding injectors from the plurality of pressure accumulators. .

Therefore, since the pressure source for supplying the fuel to the plurality of pressure accumulators is common, the supply pressure of the plurality of pressure accumulators is kept uniform, and the pressure wave generated by the injection from the injector after injection is generated. In order to prevent the pressure pulsation from propagating into the other pressure accumulator to be injected next, it is possible to supply a uniform fuel injection amount from a plurality of injectors.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment in which the present invention is applied to a 6-cylinder diesel engine is shown in FIGS. As shown in FIG. 2, the fuel pumped from the fuel tank 10 is supplied to the fuel passage 1
1 is introduced into the high-pressure injection pump 12 from the first discharge port 13 and the second discharge port 14 of the injection pump 12 via the fuel passages 16 and 17, respectively.
0, high-pressure fuel is supplied to the second pressure accumulator 21. The first pressure accumulator 20 is connected to pipes 22, 23, 24 for supplying fuel to the injectors a, b, c attached to the cylinders # 1, # 3, # 2 of the engine. Similarly,
The second pressure accumulator 21 is connected to pipes 25, 26, 27 for supplying fuel to the injectors d, e, f attached to the cylinders # 5, # 6, # 4 of the engine. Here, the injection order is, for example, # 1, # 5, # 3, # 6, #
The cylinders are in the order of 2 and # 4, and the first pressure accumulator 20 and the second pressure accumulator 21 alternately inject. Thereby, the pressure wave generated after the injection of the injector propagates to the corresponding one accumulator, but the pressure pulsation due to this pressure wave is sufficiently attenuated during the injection period from the injector corresponding to the other accumulator, The influence of the pressure wave on the injection amount of the other injector corresponding to the one pressure accumulator is negligible.

As shown in FIG. 1, the injection pump 12 has a cam chamber 3 formed in the lower end of a pump housing 2. A camshaft 4 that rotates at a speed half that of the engine is inserted into the cam chamber 3, and a cam 5 is formed on the camshaft 4. The cam 5 makes an ascending stroke of 3 degrees per one rotation of the cam shaft 4. That is, it has a form of a triple mountain cam, and the phases of the cam lifts of the cams 5 are different from each other by 120 ° pump rotation angle.

A cylinder 8 is mounted in the pump housing 2, and a cylinder shoulder portion 8d is mounted on the upper end surface 2b of the pump housing via a horseshoe-shaped shim 30 as an assembling means.
Are in contact. The plunger 31 that is reciprocally and slidably fitted in the cylinder 8 is not provided with a lead groove unlike a cylindrical plunger having a notch formed in the outer peripheral surface thereof like a conventional row pump. It has a cylindrical shape. Further, the pump chamber 32 is formed by the upper end surface of the plunger 31 and the inner peripheral surface 8a as a plunger guide hole formed in the cylinder 8, and the cylinder 8 has the pump chamber 32. Two discharge passages 3 communicating with the pump chamber 12 at the upper position in the figure
4, 35, the fuel reservoir 37 formed between the cylinder 8 and the solenoid valve 36, the communication passage 40, and the valve portion 41 of the solenoid valve 36.
A communication passage 48 is formed that communicates with the pump chamber 32 via the. The communication passage 48 includes the cylinder 8 and the pump housing 2.
Is communicated with a fuel pool 49 formed between the fuel tank and the fuel pool 49, and low-pressure fuel from a low-pressure supply pump (not shown) is supplied to the fuel pool 49 via a communication pipe 50.

The cylinder 8 is provided with two discharge valves 61 and 62 as check valves. The discharge valves 61 and 6 are provided.
2 communicates with the pump chamber 32 via the discharge ports 13 and 14. The fuel pressurized in the pump chamber 32 is discharged from the discharge valve 61,
The valve bodies 63 and 64 of 62 are pushed open against the urging force of the return springs 65 and 66, and the high pressure fuel pressurized thereby is discharged through the discharge ports 13 and 14 and the fuel passages 16 and 17 to the first pressure accumulator. 20, the pressure is fed into the second pressure accumulator 21.

The lower end of the plunger 31 is connected to a valve seat 70, and the valve seat 70 is pressed against a tappet 72 by a return spring 71. The tappet 72 has a cam roller 73, and the cam roller 73 is in sliding contact with the cam 5. Therefore, when the cam 5 is rotated by the rotation of the cam shaft 4, the plunger 31 is reciprocally driven through the cam roller 73 and the valve seat 70. The reciprocating stroke of the plunger 31 is determined by the height difference of the cam 5. Therefore, when the plunger 31 descends in the cylinder 8, the communication passage 48, the fuel reservoir 37, the communication passage 4
0, the fuel on the low pressure side is supplied to the pump chamber 32 via the valve portion 41 of the solenoid valve 36.

An electromagnetic valve 36 is screwed to the cylinder 8 at a position facing the upper end surface of the plunger 31. This solenoid valve 36 is a prestroke control type solenoid valve that sets the pressurization start time of the plunger 31 by being energized at a predetermined timing, and the first pressure accumulator is controlled by controlling the timing of energization to this solenoid valve 36. 20, the amount of discharge to the second pressure accumulator 21 can be changed.

Next, the basic operation of the fuel injection pump of the above embodiment will be described. In FIG. 1, the plunger 31, which is reciprocated with the rotation of the camshaft 4, moves inside the pump chamber 32 through the communication passage 48, the fuel reservoir 37, the communication passage 40, and the valve portion 41 of the solenoid valve 36 when descending. When the fuel is introduced to the plunger 31 and the plunger 31 rises, the plunger 31 tries to pressurize the fuel in the pump chamber 32.

However, at this time, since the solenoid valve 36 is not energized, the solenoid valve 36 is open, so that the fuel in the pump chamber 32 contains the valve portion 41, the communication passage 40, and the fuel pool 3.
7 and overflows through the passage 48 in sequence and is not pressurized. When a control pulse is sent to the solenoid valve 36 while the fuel in the pump chamber 32 is overflowing, the valve portion 41 is closed, so that the pressurization of the fuel in the pump chamber 32 by the plunger 31 is started,
When the fuel pressure in the pump chamber 32 overcomes the biasing force of the return springs 65, 66 of the discharge valves 61, 62, the valve body 6
3 and 64 are pushed open to open the fuel passage 1 from the discharge ports 13 and 14.
A first pressure accumulator 20 and a second pressure accumulator 2 via 6 and 17.
Pumped to 1.

When the plunger 31 reciprocates, the first discharge port 13 and the second
Fuel is supplied from the discharge port 14 to the first pressure accumulator 20 and the second pressure accumulator 21 via the fuel passages 16 and 17, respectively. The fuel compressed by the plunger 31 in the pump chamber 32 is discharged to the pressure accumulator having the lower internal pressure of the first and second pressure accumulators 20 and 21. Only when the internal pressures of the first and second pressure accumulators 20 and 21 become equal to each other, the pressure is discharged to both pressure accumulators. As a result, the pressures of the first pressure accumulator 20 and the second pressure accumulator 21 are uniformly maintained.

Further, the first and second pressure accumulators 20, 21
The injection waves generated in the discharge valves 61, 6 functioning as check valves while the connecting pipes of the pressure accumulators are abolished.
Since 2 is provided, the pressure wave of one pressure accumulator is not transmitted to the other pressure accumulator. This prevents the pressure pulsation due to the injection of the injector from being transmitted to the other pressure accumulator and affecting the next injection.

Next, a second embodiment of the present invention is shown in FIG.
In the second embodiment shown in FIG. 3, one discharge port 101 of the injection pump 200 is provided for each plunger. The other end of the fuel passage 102 connected to the discharge port 101 is branched into a fuel passage 103 and a second fuel passage 104. First fuel passage 103 and second fuel passage 104
The first pressure accumulator 20 or the second pressure accumulator 21 respectively.
A first check valve 105 and a second check valve 106, which prevent the fuel from flowing into the pressure feed pump 12 side, are provided respectively.

Also according to the second embodiment, the first pressure accumulator 2
The internal pressures of 0 and the second pressure accumulator 21 are controlled to be equal. That is, the fuel is preferentially supplied from the discharge port 101 of the injection pump 12 to the first fuel passage 103 or the second fuel passage 104 to the one having the lower internal pressure of the first pressure accumulator 20 and the second pressure accumulator 21. Supplied. Check valves 105, 10
This is because the fuel is supplied to the one having the larger differential pressure across the set pressure of 6.

Next, a third embodiment of the present invention is shown in FIG. The third embodiment shown in FIG. 4 is an example in which an intermediate pressure accumulating container composed of a connecting block is provided. As shown in FIG. 4, in this example, the 6 cylinders of the 6-cylinder diesel engine are divided into 3 cylinders, and the first and second cylinders are divided into cylinders # 1 and # 6, respectively.
Second accumulator 111 corresponding to the cylinders # 5 and # 2 of the pressure accumulators 110, and third pressure accumulator 112 corresponding to the cylinders of the cylinders # 3 and # 4, respectively. And the third fuel passages 120, 121, 122 are connected to each other, check valves 125, 126, 127 are provided in the middle thereof, and the intermediate pressure accumulator 130 is provided on the inlet side of these check valves 125, 126, 127.
Are connected. The intermediate pressure accumulator 130 is composed of a connecting block, and the fuel inlet is connected to the fuel passages 86 and 87. The two cylinders 88 and 89 of the injection pump 92 are connected to the fuel passages 86 and 8 via the discharge ports 93 and 94, respectively.
Connected to 7. Since the intermediate pressure accumulator 130 is composed of a connecting block, it is possible to accumulate a high pressure fuel pressure. With respect to the other components, the substantially same parts as those shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

According to this third embodiment, the injection pump 92
The high-pressure fuel discharged from the discharge ports 93, 94 is accumulated in the intermediate pressure accumulator 130, and the fuel passages 120, 121, 122 branched from the intermediate pressure accumulator 130 cause the pressure accumulators 110, 111, 112 on the downstream side. Is supplied to. Then, from the first pressure accumulator 110, the second pressure accumulator 111, and the third pressure accumulator 112, the cylinders # 1 and # 6, #
Fuel is pressure-fed to the cylinders # 5 and # 2 and the cylinders # 3 and # 4. The injection order is the order of the first, second and third pressure accumulators, for example, # 1, # 5, # 3, # 6, # 2, #.
The order is 4.

Next, conventional comparative examples are shown in FIGS. 5, 6 and 7. In Comparative Example 1 shown in FIG. 5, the first pressure accumulator 20 and the second pressure accumulator 21 are supplied from the discharge ports 143 and 144 with the fuel pressure-fed by separate plungers.
Since the internal pressure of the first pressure accumulator 20 and the internal pressure of the second pressure accumulator 21 may become non-uniform due to variations in the performance of each cylinder of the injection pump, variations in the fuel injection amount among a plurality of injectors occur. There is a risk of

The second comparative example shown in FIG. 6 is the first pressure accumulator 20.
And the second pressure accumulator 21 are connected by a connection pipe 141. In this example, the injection wave injected by the injector on the first pressure accumulator 20 side passes through the connection pipe 141 to the second injection wave.
Since it is transmitted to the pressure accumulator 21, the fuel injection amount may vary among the injectors for the next injection.

A comparative example 3 shown in FIG. 7 is a pressure feed pump 140.
The fuel discharged from the discharge port 147 of the first accumulator 20
In this example, the first pressure accumulator 20 and the second pressure accumulator 21 are connected by a connection pipe 141. According to this example, the injection wave from the injector generated in the first pressure accumulator 20 and the second pressure accumulator 21 is connected to the connecting pipe 141.
Since they are transmitted to the pressure accumulator on the other side via
Due to the influence of the injection wave, the injection quantity from each injector is likely to vary.

Compared to the first, second, and third comparative examples, in the present embodiment described above, since the internal pressure between the plurality of pressure accumulators is always kept uniform, the variation in the injection amount among the injectors is prevented and at the same time. , The non-uniformity of the fuel due to the injection wave is prevented because the check valve prevents the propagation of the fuel injection wave so that the injection wave of the fuel from the injector does not affect the injection amount of the next injector. .

As the fuel pressurizing source, for example, a gear pump may be used without using the plunger. It should be noted that in the above-described embodiment, an example in which the present invention is applied to a 6-cylinder engine has been described, but it goes without saying that the present invention can also be applied to an engine having four cylinders, eight cylinders, or the like.

[0029]

As described above, according to the pressure accumulation type fuel injection device of the present invention, the pressure accumulation container is divided corresponding to a plurality of cylinders, and the uniform fuel from the pressure pump is supplied to each of the divided pressure accumulation containers. Since pressure is applied and a check valve is provided on the fuel inlet side of a plurality of divided pressure accumulators, the internal pressure of the plurality of divided accumulators is always kept uniform and the injection pressure wave is Since it does not propagate to the pressure accumulator container, it is effective in preventing non-uniformity of the injection amount.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of a pressure accumulation type fuel injection device showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a pressure accumulation type fuel injection device according to a first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a pressure accumulation type fuel injection device according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a pressure accumulation type fuel injection device according to a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a conventional pressure accumulation type fuel injection device according to a first comparative example.

FIG. 6 is a schematic configuration diagram showing a pressure-accumulation fuel injection device according to a conventional comparative example 2.

FIG. 7 is a schematic configuration diagram showing a conventional pressure-accumulation fuel injection device according to a third comparative example.

[Explanation of symbols]

 a, b, c, d, e, f injector 12 injection pump 13 first discharge port 14 second discharge port 16 first fuel passage 17 second fuel passage 20 first pressure accumulator 21 second pressure accumulation Device 31 Plunger 32 Pump chamber 61 Discharge valve (check valve) 62 Discharge valve (check valve)

Claims (1)

[Claims] 1. An entire cylinder is divided into a plurality of groups each including a plurality of injectors provided for each cylinder of a multi-cylinder engine and injectors of the same cylinder whose injection order is not adjacent to each other. In a fuel injection device that includes a plurality of pressure accumulators provided for each group and injects high-pressure fuel stored in the plurality of pressure accumulators from corresponding injectors at a predetermined time, the fuel in the pump chamber is pressure-fed from the discharge port. An injection pump, a plurality of fuel passages branching from the pump chamber or a passage communicating with the pump chamber and communicating with the plurality of accumulators, and pressures generated after the injector is provided in the plurality of fuel passages. A pressure-accumulation fuel injection device, comprising: a check valve that prevents waves from transmitting from a corresponding pressure accumulator to another pressure accumulator.