JPH10318060A - Pressure accumulation type fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the necessity of a pressure reducing valve and a fuel returning passage so as to miniaturize a device and reduce costs by providing a two-way type valve in a fuel supply passage extended from a forced-feed pump to a fuel pressure accumulation part and causing fuel in the fuel pressure accumulation part to reversibly flow to the forced-feed pump during the decompression of the fuel pressure accumulation part. SOLUTION: During the normal running of an engine, fuel in a fuel tank 1 is supplied by a feed pump 3 through a fuel supply passage 2 into the plunger room 7 of a forced-feed pump 4. The fuel in the plunger room 7 is pressurized by a plunger 6 and, when a pressure in the plunger room 7 reaches a pressure higher in a fuel pressure accumulation part 10, the fuel is supplied to the fuel pressure accumulation part 10. Then, during the speed reduction of the engine, for reducing a fuel pressure in the fuel pressure accumulation part 10, the forced-feed pump outlet valve of a actuator 9 for an outlet valve is opened and, when the plunger 6 is lowered, the fuel in the fuel pressure accumulation room 7 is supplied reversibly to the forced-feed pump 4 and then the pressure in the fuel pressure accumulation part 10 and the pressure in the plunger room 7 are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator type fuel injection device.

[0002]

2. Description of the Related Art Conventionally, in order to inject fuel from an injector, as shown in FIG. 5, an accumulator type fuel injection device including a fuel tank, a feed pump, a pressure pump, a fuel accumulator (common rail), and an injector has been known. Are known.
FIG. 5 is a schematic configuration diagram of a conventional pressure-accumulation fuel injection device.
In FIG. 5, 101 is a fuel tank, 102 is a fuel supply passage, 103 is a feed pump, 104 is a pressure feed pump,
105 is a pressurizing cam, 106 is a plunger, 107 is a plunger chamber, 108 is an inlet valve actuator, 109
Is a pump check valve (may be a one-way valve), 110
Is a fuel pressure accumulator, 111 is an injector passage, 112 is a pressure reducing valve, 113 is a fuel return passage, 151 is a pressure feed pump inlet valve, 152 is an inlet valve solenoid, 153 is an inlet valve spring, and 161 is a ball (check valve ball). May be)
162 is a check valve spring.

[0003] During a steady operation of the engine, as shown in FIG.
At 03, a predetermined feed pressure is supplied to the pressure pump 104 via the fuel supply passage 102. When fuel flows into the plunger chamber 107 of the pressure pump 104, the inlet valve solenoid 152 of the inlet valve actuator 108
Does not work, and the pumping pump inlet valve 151 is located at the valve open position by the action of the inlet valve spring 153. The plunger 106 is lowered by the action of the pressing cam 105. The ball 161 of the pressure-feed pump check valve 109 is located at the valve closing position by the action of the check valve spring 162. In this case, the pressure inside the plunger chamber 107 is
It is smaller than the pressure in 10.

[0004] Subsequently, the fuel in the plunger chamber 107 is
Plunger 1 raised by the action of pressurizing cam 105
06, pressurization. An ECU (not shown) determines the amount of fuel to be pumped to the fuel accumulator 110 according to operating conditions. That is, when a small amount of pressure is sufficient, the pressure pump inlet valve 151 holds the open position, and the plunger chamber 107 is opened.
The fuel sucked into the tank passes through the feed pump 103 again and is returned to the fuel tank 101. After the plunger 106 is lifted to some extent, the solenoid for the inlet valve 152 is excited by the ECU, the pumping pump inlet valve 151 is in the closed position, and pressurization starts in the plunger chamber 107. The ball 161 of the pressure-feed pump check valve 109 is located at the valve closing position by the action of the check valve spring 162. In this case, the pressure in the plunger chamber 107 is
Smaller than the pressure inside. When the pressure in the plunger chamber 107 becomes higher than the pressure (feed pressure) in the fuel supply passage 102 on the side of the feed pump 103, the pressure-feeding pump inlet valve 151 is maintained even if the energization of the inlet valve solenoid 152 is stopped. , Continue to be in the closed position.

When the plunger 106 rises, the pressure in the plunger chamber 107 is equal to or higher than the pressure in the fuel accumulator 110 (strictly, the sum of the pressure in the fuel accumulator 110 and the pressure of the check valve spring 162). When the size becomes large, the ball 161 of the pumping check valve 109 moves to the valve opening position. As a result, the fuel in the plunger chamber 107 rises due to the action of the pressurizing cam 105.
6 supplies the fuel to the fuel accumulator 110. As the plunger 106 rises, the pressure in the plunger chamber 107 and the pressure in the fuel accumulator 110 increase.

When the plunger 106 passes through the top dead center and shifts to a downward stroke, the pressure in the plunger chamber 107 rapidly decreases. Therefore, the ball 161 of the pumping check valve 109 moves to the valve closing position. Therefore, the pressure in the fuel pressure accumulating unit 110 is kept constant without decreasing. When the pressure in the plunger chamber 107 decreases to the feed pressure (strictly, the sum of the feed pressure and the pressure of the inlet valve spring 153) with the lowering of the plunger 106, the pressure pump of the inlet valve actuator 108 The inlet valve 151 moves to the valve opening position by the action of the inlet valve spring 153. As a result, the pressure in the plunger chamber 107 is maintained at the magnitude of the feed pressure. Subsequently, the fuel in the fuel accumulator 110 is supplied to an injector (not shown) through the injector passage 111 and is injected from the injector.

On the other hand, during the deceleration operation of the engine, when it is not necessary to maintain the pressure in the fuel accumulator 110 at a high pressure,
By opening the pressure reducing valve 112, the fuel in the fuel accumulator 110 is supplied to the fuel tank 1 through the fuel return passage 113.
Returned to 01. As a result, the pressure in the fuel accumulator 110 decreases to a desired pressure. Since the pump check valve 109 is a check valve, the fuel in the fuel accumulator 110 cannot flow back through the fuel supply passage 102 to the pump 108 and the fuel tank 101.
An example of this type of accumulator type fuel injection device is described in, for example, Japanese Patent Application Laid-Open No. 7-103029.

[0008]

In the case of the pressure accumulating type fuel injection device shown in FIG. 5, in order to return the fuel in the fuel accumulating section to the pressure pump and the fuel tank, the pressure reducing valve and the fuel supply passage are provided. A fuel return passage is required. Therefore, the size of the apparatus is increased, and the cost is increased due to an increase in the number of parts. Further, since the high pressure of the fuel in the fuel accumulator rapidly decreases to the atmospheric pressure (pressure in the fuel tank), the fuel temperature increases, and the viscosity of the fuel decreases. Therefore, the sealing effect is reduced in each part in the device. Furthermore, since the fuel in the fuel accumulator returns to the fuel tank without performing work such as urging the rotation of the pressurizing cam, the energy of the fuel in the fuel accumulator is wasted. Further, during deceleration operation of the engine, since the pressure in the plunger chamber has decreased, the plunger
The fuel in the plunger chamber is not biased toward the pressurizing cam. Therefore, when the cam rotates at high speed during the deceleration operation of the engine, the plunger is separated from the cam after passing through the top dead center due to inertia, and a collision sound is generated when the plunger and the cam come into contact again.

In view of the above-mentioned problems, the present invention achieves downsizing and cost reduction of the apparatus by eliminating the pressure reducing valve and the fuel return passage, while reducing the fuel viscosity and increasing the sealing effect based on the rise in fuel temperature. Pressure-accumulation type fuel injection device which can prevent a decrease in fuel consumption, improve fuel efficiency by effectively utilizing energy of fuel in a fuel pressure accumulating section, and can prevent generation of a collision sound between a plunger and a cam. The purpose is to do.

[0010]

According to the first aspect of the present invention, there is provided a pressure-accumulation type fuel injection system in which a valve is provided in a fuel supply passage extending from a pressure pump to a fuel pressure accumulating section.
A pressure-accumulation fuel injection device is provided, wherein the valve is a two-way valve, and when the fuel pressure accumulator is depressurized, fuel in the fuel pressure accumulator is caused to flow back to the pressure pump.

[0011] The accumulator type fuel injection device according to claim 1 is
By causing the fuel in the fuel accumulator to flow backward through the two-way valve and the fuel supply passage, the pressure in the fuel accumulator can be reduced. Therefore, the pressure reducing valve and the fuel return passage can be eliminated, and the size and cost of the device can be reduced. Further, when the fuel in the fuel accumulator returns to the fuel pump, the fuel passes through the pressure pump so that the pressure of the fuel can be gradually reduced. for that reason,
A sharp rise in fuel temperature and a corresponding decrease in fuel viscosity,
Furthermore, it is possible to prevent a reduction in the sealing effect based on them. Further, since the fuel flowing backward from the fuel pressure accumulating unit to the fuel tank passes through the pump, the fuel can urge the rotation of the pressurizing cam in the pump.
Fuel efficiency can be improved. In addition, during the deceleration operation of the engine, since the fuel flowing backward from the fuel pressure accumulating portion exists in the plunger chamber, a predetermined pressure is maintained in the plunger chamber. Therefore, the plunger is always urged toward the pressurizing cam by the fuel in the plunger chamber. As a result, even when the cam rotates at a high speed during the deceleration operation of the engine, the plunger does not separate from the cam after passing through the top dead center due to inertia, and no collision sound between the plunger and the cam is generated.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of one embodiment of a pressure accumulating fuel injection device according to the present invention. In FIG. 1, 1 is a fuel tank, 2 is a fuel supply passage, 3 is a feed pump, 4
Is, for example, a pump for one cylinder of a line type two-cylinder pump for six cylinders. A pressure feed pump, 5 is a pressurizing cam, 6 is a plunger, 7 is a plunger chamber, 8 is an actuator for an inlet valve, and 9 is an outlet. A valve actuator, 10 is a fuel pressure accumulator,
11 is an injector passage, 51 is a pressure pump inlet valve, 5
2 is an inlet valve solenoid, and 53 is an inlet valve spring.
FIG. 2 is an enlarged sectional view of the outlet valve actuator of FIG. In FIG. 2, reference numeral 61 denotes a pressure pump outlet valve, 62 denotes an outlet valve spring, and 63 denotes an outlet valve solenoid. FIG.
Is the pressure in the fuel accumulator during steady operation of the engine,
The relationship between the pressure in the plunger chamber, the energized state of the inlet valve solenoid and the outlet valve solenoid, the open / closed state of the pressure pump inlet valve and the pressure pump outlet valve, and the position of the plunger (that is, cam lift) and time are shown.

During normal operation of the engine, as shown in FIGS. 1, 2 and 3, the fuel in the fuel tank 1 is supplied to the fuel supply passage 2 by a feed pump 3 at a predetermined feed pressure.
Is supplied to the pressure feed pump 4 via the. When fuel flows into the plunger chamber 7 of the pump 4 (time b to time b in FIG. 3)
When the fuel in the plunger chamber 7 flows back to the fuel supply passage 2 due to the plunger 6 ascending and (c), the solenoid 5 for the inlet valve of the actuator 8 for the inlet valve is used.
2 does not act (non-energized), and the pressure pump inlet valve 51 is located at the valve open position by the action of the inlet valve spring 53. The plunger 6 is lowered by the action of the pressing cam 5. The outlet valve solenoid 63 of the outlet valve actuator 9 does not act (non-energized), and the pumping pump outlet valve 61 is located at the valve closing position by the action of the outlet valve spring 62. In this case, the pressure in the plunger chamber 7 is smaller than the pressure in the fuel accumulator 10.

Subsequently, the fuel in the plunger chamber 7 is raised by the plunger 6 raised by the action of the pressurizing cam 5.
Pressurization (time d to e in FIG. 3). In that case, the pumping pump inlet valve 51 of the inlet valve actuator 8 is located at the valve closed position by the action of the inlet valve solenoid 52 (energization). The outlet valve solenoid 63 of the outlet valve actuator 9 does not act (non-energized), and the pressure pump outlet valve 61
The outlet valve spring 62 acts to position the valve in the closed position.
In this case, the pressure in the plunger chamber 7 becomes
Smaller than the pressure inside. When the pressure in the plunger chamber 7 becomes larger than the pressure (feed pressure) in the fuel supply passage 2 on the side of the feed pump 3, the solenoid 5 for the inlet valve may be used.
Even if the energization of 2 is stopped, the pressure-feeding pump inlet valve 51 continues to be located at the valve closing position.

Due to the rise of the plunger 6, the pressure in the plunger chamber 7 becomes higher than the pressure in the fuel accumulator 10 (strictly, the sum of the pressure in the fuel accumulator 10 and the pressure of the outlet valve spring 62). When the size becomes large (time e to a ′ in FIG. 3), the pressure-feeding pump outlet valve 61 of the outlet valve actuator 9 moves to the valve opening position even though the outlet valve solenoid 63 does not operate (non-energized). I do. As a result, the fuel in the plunger chamber 7 is supplied to the fuel accumulator 10 by the plunger 6 which rises by the action of the pressurizing cam 5.
As the plunger 6 rises, the pressure in the plunger chamber 7 and the pressure in the fuel accumulator 10 increase.

When the plunger 6 passes through the top dead center and moves to the descending stroke (time a 'to b' in FIG. 3), the pressure in the plunger chamber 7 decreases rapidly. Therefore, the pressure pump outlet valve 61 of the outlet valve actuator 9 moves to the valve closing position. Therefore, the pressure in the fuel accumulator 10 is kept constant without decreasing. When the pressure in the plunger chamber 7 decreases to the feed pressure (strictly, the sum of the feed pressure and the spring 53 for the inlet valve) with the lowering of the plunger 6 (time b ′ in FIG. 3), the inlet valve Pump pump inlet valve 51 of actuator 8 moves to the valve opening position by the action of inlet valve spring 53. As a result, the pressure in the plunger chamber 7 is maintained at the magnitude of the feed pressure. Subsequently, the fuel in the fuel accumulator 10 is supplied to the injector passage 11.
Is supplied to an injector (not shown) through the injector, and is injected from the injector. (Time i ′ in FIG. 3).

Next, a description will be given of the accumulator type fuel injection device of the present embodiment during the deceleration operation of the engine. FIG.
During the deceleration operation of the engine, the pressure in the fuel accumulator, the pressure in the plunger chamber, the energized state of the solenoid for the inlet valve and the solenoid for the outlet valve, the open / closed state of the pumping pump inlet valve and the pumping pump outlet valve, and the position of the plunger (that is, (Cam lift) and time.

During the deceleration operation of the engine, the lower the fuel pressure in the fuel accumulator 10 required after the deceleration is, the better. Therefore, it is desired to reduce the pressure in the fuel accumulator 10. First, before the start of deceleration (that is, during steady operation), when the plunger 6 is raised by the action of the pressurizing cam 5 (time d in FIG. 4), the action of the inlet valve solenoid 52 of the inlet valve actuator 8 causes ( Energized), pressure pump inlet valve 5
1 moves to the valve closing position. After that, even if the energization of the inlet valve solenoid 52 is stopped, as long as the pressure in the plunger chamber 7 is equal to or higher than the feed pressure, the pumping pump inlet valve 51 continues to be in the valve closing position (see FIG. 4). Time d ~
g ').

After the start of deceleration of the engine (time a 'in FIG. 4)
f ′), by the action of the outlet valve solenoid 63 of the outlet valve actuator 9 (energized), the pressure pump outlet valve 61
Is located at the valve opening position. The inlet valve solenoid 52 of the inlet valve actuator 8 does not operate (non-energized), but as described above, the pumping pump inlet valve 51 remains at the closed position. The plunger 6 is lowered by the action of the pressing cam 5. As a result, the fuel in the fuel accumulator 10 flows back to the pump 4 via the fuel supply passage 2 and the pump outlet valve 61, and the pressure in the fuel accumulator 10 and the pressure in the plunger chamber 7 decrease. . In other words, in the conventional case, the fuel in the fuel pressure accumulating unit was suddenly returned to the fuel tank via the pressure reducing valve and the fuel return passage, so that the pressure rapidly decreased, and the fuel temperature increased and the viscosity decreased. ,
In the case of the present embodiment, the fuel in the fuel pressure accumulating unit 10 is firstly depressurized in the plunger chamber 7, so that the pressure gradually decreases. As a result, the fuel temperature does not increase and the viscosity does not decrease, and the sealing effect does not decrease.

Since the pumping pump inlet valve 51 is closed, the pumping pump outlet valve 61 is open, and the plunger 6 is in the downward stroke during the time a 'to f' in FIG. The flow of fuel flowing backward from the fuel accumulator 10 into the plunger chamber 7 urges the lowering operation of the plunger 6, that is, the rotating operation of the pressurizing cam 5. As a result, fuel efficiency of the engine can be improved.

The predetermined timing determined by the ECU (see FIG. 4)
When the energization of the outlet valve solenoid 63 of the outlet valve actuator 9 is stopped at the time f ′), the action of the fuel flowing backward from the fuel accumulator 10 into the plunger chamber 7 and the action of the outlet valve spring 62 cause The pump outlet valve 61 moves to the valve closing position. As a result, the pressure in the fuel pressure accumulating section 10 stops decreasing.

Subsequently, since the plunger 6 is lowered by the action of the pressure cam 5, the pressure in the plunger chamber 7 decreases (time f 'to g' in FIG. 4). Subsequently, when the pressure in the plunger chamber 7 and the feed pressure (strictly, the sum of the feed pressure and the inlet valve spring 53) become equal (time g 'in FIG. 4), the pump for pumping the inlet valve actuator 9 is turned on. The inlet valve 51 moves to the valve opening position by the action of the inlet valve spring 53. In this case, the pressure pump outlet valve 61 of the outlet valve actuator 9 remains at the valve closing position because the pressure in the fuel accumulator 10 is higher than the pressure in the plunger chamber 7. The plunger 6 is raised by the action of the pressing cam 5. As a result, the fuel in the plunger chamber 7
The fuel is returned to the fuel tank 1 via the fuel supply passage 2 on the feed pump 3 side and an auxiliary passage (not shown) branched from the fuel supply passage 2.

Subsequently, while the plunger 6 is raised by the action of the pressure cam 5 (time g'-d 'in FIG. 4), the EC
At a predetermined timing determined by U (time d ′ in FIG. 4), the action of the inlet valve solenoid 52 of the inlet valve actuator 8 (energization) causes the pumping pump inlet valve 51 to
Move to valve closing position. In this case, the pressure-feeding pump outlet valve 61 of the outlet valve actuator 9 is located at the valve closing position because the pressure in the fuel accumulator 10 is higher than the pressure in the plunger chamber 7 as in the case described above. While the plunger 6 continues to rise (time d 'to a "in FIG. 4), the pressure in the plunger chamber 7 rises until it becomes equal to the pressure in the fuel accumulator 10. The time d' described above is Time a "
Is determined by the ECU based on the numerical value obtained by the pressure sensor so that the pressure in the fuel pressure accumulating unit 10 and the pressure in the plunger chamber 7 become equal.

When the plunger 6 passes through the top dead center (FIG. 4)
Time a ″), the fuel accumulator 10
A sufficient amount of fuel is present such that the pressure in the plunger chamber 7 is equal to the pressure in the plunger chamber 7. Therefore, unlike the conventional case, the plunger 6 is urged toward the pressurizing cam 5 by the fuel in the plunger chamber 7. As a result, even when the pressure cam 5 rotates at a high speed, the plunger 6 does not separate from the cam by inertia after passing through the top dead center, and no collision noise is caused by the plunger and the cam coming into contact again.

When the plunger 6 passes through the top dead center and shifts to the descending stroke (time a "to f" in FIG. 4), the action of the outlet valve solenoid 63 of the outlet valve actuator 9 (energization) causes the pressure pump The outlet valve 61 moves to the valve opening position. In this case, as described above, the pressure pump inlet valve 51 is located at the valve closed position because the pressure in the plunger chamber 7 is equal to or higher than the feed pressure. As a result, the fuel in the fuel pressure accumulating unit 10 flows back to the pressure pump 4 via the fuel supply passage 2 and the pressure pump outlet valve 61, and the fuel pressure accumulator 1
0 and the pressure in the plunger chamber 7 decrease.

By repeating the above steps, the pressure in the fuel accumulator 10 is reduced to a desired pressure.
In this embodiment, since the pressure pump outlet valve 61 is a two-way valve, the pressure reducing valve and the fuel return path, which were required in the conventional case, can be eliminated, and the size and cost of the apparatus can be reduced. Can be achieved.

[0028]

According to the present invention, by reducing the size and cost of the apparatus by eliminating the pressure reducing valve and the fuel return passage, the fuel viscosity is reduced and the sealing effect is reduced due to the increase in the fuel temperature. By effectively utilizing the energy of the fuel in the fuel accumulator, fuel efficiency can be improved, and furthermore, it is possible to prevent the sound of collision between the plunger and the cam.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an accumulator type fuel injection device of the present invention.

FIG. 2 is an enlarged sectional view of a pressure pump outlet valve of FIG. 1;

FIG. 3 shows the pressure in the fuel pressure accumulator, the pressure in the plunger chamber, the energized state of the solenoid for the inlet valve and the solenoid for the outlet valve, the open / closed state of the pumping pump inlet valve and the pumping pump outlet valve, and the plunger during steady operation of the engine. 3 is a drawing showing the relationship between the position (i.e., cam lift) and time.

FIG. 4 shows the pressure in the fuel pressure accumulating section, the pressure in the plunger chamber, the energized state of the solenoid for the inlet valve and the solenoid for the outlet valve, the open / closed state of the pumping pump inlet valve and the pumping pump outlet valve, and the plunger during deceleration operation of the engine. 3 is a drawing showing the relationship between the position (i.e., cam lift) and time.

FIG. 5 is a schematic configuration diagram of a conventional pressure accumulating fuel injection device.

[Explanation of symbols]

 2 ... fuel supply passage 4 ... pressure pump 9 ... actuator for outlet valve 10 ... fuel pressure accumulator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16K 17/02 F16K 17/02 B 17/04 17/04 Z

Claims (1)

[Claims] In a pressure accumulating type fuel injection device provided with a valve in a fuel supply passage extending from a pressure feed pump to a fuel pressure accumulating section, the valve is a bidirectional valve, and when the fuel pressure accumulating section is depressurized, the fuel pressure accumulating section is provided. A pressure-accumulation type fuel injection device, characterized in that fuel in the section is caused to flow back to the pump.