JP2007009848A - Regulator valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a piston 22 from being excessively lifted by increasing damper effect without impairing the responsiveness of a regulator valve 4. <P>SOLUTION: In this regulator valve 4, a damper chamber 29 is formed at the rear of a piston 22, and a fuel goes in and out of the damper chamber 29 through a breathing hole 28 according to the behavior of the piston 22. The breathing hole 28 is connected to the cam chamber 19 of a high-pressure pump 3 through a fuel passage 27. Since a positive pressure fuel is fed from the cam chamber 19 of the high-pressure pump 3 to the damper chamber 29 through the fuel passage 27, even if an abnormally large negative pressure occurs on the intake side of a feed pump 2, the damper chamber 29 is not brought into a negative pressure state, and can always maintain a positive pressure. As a result, since the damper effect of the damper chamber 29 is increased, the excessive lift of the piston 22 can be suppressed and the discharge pressure of the feed pump 2 can be rapidly stabilized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a regulating valve for regulating the discharge pressure of a feed pump.

Conventionally, a fuel injection pump used in a pressure accumulation fuel injection system such as a diesel engine is known (see Patent Document 1). As shown in FIG. 12, this fuel injection pump uses a regulating valve 120 for regulating the discharge pressure of the feed pump 110 that pumps fuel from the fuel tank 100 (fuel pressure discharged from the feed pump 110). ing.
The regulating valve 120 includes an inlet 130 connected to the discharge side of the feed pump 110, a valve body 160 formed with a relief hole 140 and a breathing hole 150 connected to the suction side of the feed pump 110, and an inlet 130. The piston 170 is configured to receive a discharge pressure of the feed pump 110 introduced from the feed pump 110 and move inside the valve body 160, a spring 180 that urges the piston 170 against the discharge pressure of the feed pump 110, and the like. The discharge pressure of the feed pump 110 is adjusted to a predetermined pressure according to the valve opening position of the piston 170 with respect to 140.
JP 2000-240531 A

  However, the regulating valve 120 described above is used when the feed pump 110 has an abnormally excessive negative pressure or when air is mixed into the fuel sucked into the feed pump 110. Since the discharge pressure becomes unstable, the piston 170 repeats reciprocating motion with a large amplitude. At this time, if the lift amount of the piston 170 (the amount of movement in the direction in which the spring 180 is compressed) becomes excessive, the spring 180 is fully compressed (adhered) beyond the allowable stroke, causing damage. Further, the plug 190 that supports the spring 180 between the piston 170 and the valve body 160 may come off. The allowable stroke of the spring 180 represents the use range of the spring 180 and is not compressed more than the allowable stroke in a normal use state.

However, the regulator valve 120 is provided with a damper chamber 200 behind the piston 170 and has a function of preventing an excessive lift of the piston 170 due to a damper effect of the fuel filled in the damper chamber 200. At present, a sufficient damper effect is not obtained. That is, since the damper chamber 200 is connected to the suction side of the feed pump 110 through the breathing hole 150, for example, if an excessive negative pressure is generated at the inlet of the feed pump 110, the negative pressure also acts on the damper chamber 200. As a result, an excessive lift of the piston 170 is promoted (see FIG. 3).
In addition, when air is mixed into the fuel sucked into the feed pump 110, air is also mixed into the fuel in the damper chamber 200, so that the damper effect is unavoidably reduced.

Although it is conceivable to reduce the opening area of the breathing hole 150 in order to enhance the damper effect, in this case, the movement of the piston 170 that opens and closes the relief hole 140 is suppressed, so that the responsiveness of the regulating valve 120 is reduced. A worsening problem arises.
The present invention has been made based on the above circumstances, and an object of the present invention is to provide a regulated valve capable of enhancing a damper effect and preventing an excessive lift of a piston without impairing responsiveness.

(Invention of Claim 1)
The regulating valve used in the fuel injection device of the present invention opens a damper chamber formed on the counter-flow inlet side of the piston inside the body and the side surface of the body that forms the damper chamber, thereby causing the behavior of the piston. Accordingly, the damper chamber communicates with a pressure system having a positive fuel pressure lower than the discharge pressure of the feed pump via a fuel passage connected to the breather hole. It is characterized by that.

The above regulator valve is filled with fuel of positive pressure (pressure lower than the discharge pressure of the feed pump) in the damper chamber via the fuel passage, so that excessive negative pressure is generated on the suction side of the feed pump. However, the damper chamber does not become negative pressure and can always maintain positive pressure. In addition, even when air is mixed into the fuel sucked into the feed pump, the fuel pressure in the damper chamber is maintained at a positive pressure, so that the air mixed into the fuel in the damper chamber is less than that in the conventional regulating valve. Less. Thereby, since the damper effect by the fuel of a damper chamber can be improved, the excessive lift of a piston can be suppressed.
Further, in the present invention, since it is not necessary to reduce the opening area of the breathing hole in order to enhance the damper effect, the responsiveness of the regulating valve is not impaired.

(Invention of Claim 2)
2. The regulating valve according to claim 1, wherein the cam means is accommodated therein, and a part of the fuel discharged from the feed pump is supplied as lubricating oil for the cam means, and overflows from the cam chamber. The damper chamber is used for a fuel injection device having an overflow passage through which fuel returns to the fuel tank, and the damper chamber communicates with the cam chamber via a fuel passage connected to a breathing hole.
According to the above configuration, the damper chamber and the cam chamber communicate with each other through the fuel passage, and the cam chamber communicates with the fuel tank through the overflow passage. As a result, the fuel pressure (for example, atmospheric pressure) in the fuel tank is introduced into the damper chamber and is always filled with positive pressure fuel, so that the damper effect by the fuel in the damper chamber can be improved, and the piston is lifted excessively. Can be suppressed.

(Invention of Claim 3)
2. The regulating valve according to claim 1, wherein the cam means is accommodated therein, and a part of the fuel discharged from the feed pump is supplied as lubricating oil for the cam means, and overflows from the cam chamber. The damper chamber is used for a fuel injection device having an overflow passage for returning the fuel to the fuel tank, and the damper chamber communicates with the overflow passage through the fuel passage connected to the breathing hole.
According to the above configuration, the damper chamber communicates with the overflow passage via the fuel passage, and the overflow passage communicates with the fuel tank. As a result, the fuel pressure (for example, atmospheric pressure) in the fuel tank is introduced into the damper chamber and is always filled with positive pressure fuel, so that the damper effect by the fuel in the damper chamber can be improved, and the piston is lifted excessively. Can be suppressed.

(Invention of Claim 4)
The regulation valve according to claim 1 is characterized in that the damper chamber communicates with the fuel tank through a fuel passage connected to the breathing hole.
According to the above configuration, since the damper chamber communicates with the fuel tank via the fuel passage, the fuel pressure (for example, atmospheric pressure) in the fuel tank is introduced into the damper chamber. As a result, since the positive pressure fuel is always filled in the damper chamber, the damper effect by the fuel in the damper chamber can be improved, and the excessive lift of the piston can be suppressed.

(Invention of Claim 5)
5. The regulator valve according to claim 1, wherein the damper chamber communicates with the discharge side of the feed pump through a throttle passage having an orifice. In this case, not only the fuel pressure of the pressure system described in the invention of claim 1 but also the discharge pressure of the feed pump is introduced into the damper chamber via the throttle passage. Thereby, compared with the case where only the fuel pressure of the pressure system is introduced into the damper chamber, the fuel pressure in the damper chamber becomes higher, so that the damper effect of the damper chamber can be further improved.

(Invention of Claim 6)
The regulation valve according to claim 5 is characterized in that the throttle passage is formed through the piston, and the inlet and the damper chamber are communicated with each other through the throttle passage.
In this case, since it is not necessary to form the throttle passage in the housing body of the fuel injection pump, the processing of the throttle passage is easy.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

FIG. 1 is a schematic diagram illustrating a configuration of a fuel injection pump 1 according to the first embodiment.
The fuel injection pump 1 shown in the first embodiment is used in, for example, a pressure accumulation fuel injection device for a diesel engine, and includes a feed pump 2, a high-pressure pump 3, a regulating valve 4, and the like described below.
The feed pump 2 is constituted by, for example, a well-known trochoid pump (see FIG. 11). The feed pump 2 is driven by the camshaft 5 and sucks the fuel pumped up from the fuel tank 6 through the filter 7, pressurizes it to a predetermined pressure, and discharges To do.

The high-pressure pump 3 includes cam means (described below) that converts the rotational motion of the cam shaft 5 into reciprocating motion, and a plunger 9 that reciprocates inside the cylinder 8 by transmitting the reciprocating motion of the cam means.
The cam means includes an eccentric cam 10 provided on the cam shaft 5, a cam ring 12 fitted to the outer periphery of the eccentric cam 10 via a bearing 11 (see FIG. 11), and an outer peripheral surface of the cam ring 12. The tappet 13 is in contact with the (flat surface) and the like. The tappet 13 is integrally provided at the end of the plunger 9 and is pressed against the outer peripheral surface of the cam ring 12 by a spring 14. When the cam shaft 5 rotates, the cam means is converted into a reciprocating motion by the relative rotation of the eccentric cam 10 and the cam ring 12, and the reciprocating motion is transmitted to the plunger 9 through the tappet 13.

The plunger 9 receives a reciprocating motion from the cam means, thereby moving the inside of the cylinder 8 from the top dead center toward the bottom dead center, and the inside of the cylinder 8 from the bottom dead center to the top dead center. The pumping stroke that moves toward the head is repeated.
In the high-pressure pump 3, the fuel discharged from the feed pump 2 is pushed into the cylinder 8 by the suction stroke of the plunger 9 and is sucked into the cylinder 8, and is sucked into the cylinder 8 by the pressure-feed stroke of the plunger 9. The pressurized fuel is pressurized, and the discharge valve 16 is pushed open to be pumped to a common rail (not shown).

The fuel discharged from the feed pump 2 is metered by the electromagnetic metering valve 17 provided between the feed pump 2 and the suction valve and sucked into the cylinder 8, and the surplus fuel other than that is fed The fuel supplied to the cam chamber 19 through the gallery 18 and overflowed from the cam chamber 19 returns to the fuel tank 6 through the overflow passage 20. The cam chamber 19 is provided with the above cam means and is lubricated by the fuel supplied through the feed gallery 18.
The electromagnetic metering valve 17 is an electromagnetic valve whose valve opening degree is controlled by an electronic control unit (ECU / not shown) based on the operation state of the diesel engine.

As shown in FIG. 2, the regulating valve 4 includes a cylindrical valve body 21, a piston 22 that is reciprocally inserted into the valve body 21, and the piston 22 in one direction (left direction in the figure). And has a function of adjusting the discharge pressure of the feed pump 2 to a predetermined pressure.
The valve body 21 has an opening on one end side (left side in the drawing) as a fuel inlet 24 and an opening on the other end side closed by a plug 25. The inlet 24 is connected to the feed gallery 18, and the discharge pressure of the feed pump 2 is introduced through the feed gallery 18. A relief hole 26 connected to the suction side of the feed pump 2 and a vent hole 28 connected to the cam chamber 19 of the high-pressure pump 3 through the fuel passage 27 are formed on the side surface of the valve body 21.

The relief hole 26 is opened and closed by the piston 22, and communicates with the inflow port 24 when the piston 22 opens the relief hole 26.
The breathing hole 28 is provided inside the valve body 21 so as to be able to communicate with a damper chamber 29 formed between the piston 22 and the plug 25, and the piston 22 moves in a direction to close the relief hole 26 to move the breathing hole 28. When it opens, it communicates with the damper chamber 29, and when the piston 22 moves in the direction of opening the relief hole 26 and closes the breathing hole 28, communication with the damper chamber 29 is blocked. The damper chamber 29 is filled with fuel from the cam chamber 19 through the fuel passage 27.

The piston 22 moves inside the valve body 21 and varies the opening area of the relief hole 26 due to fluctuations in the discharge pressure of the feed pump 2 introduced into the inlet 24.
The spring 23 is disposed behind the piston 22 (damper chamber 29) and urges the piston 22 in one direction against the discharge pressure of the feed pump 2 acting on the front surface of the piston 22. As a result, the piston 22 is balanced at a position where the discharge pressure of the feed pump 2 acting on the front surface of the piston 22 and the fuel pressure of the damper chamber 29 acting on the back surface + the reaction force of the spring 23 are balanced.

Next, the operation and effect of the regulating valve 4 will be described.
The regulator valve 4 is configured so that the piston 22 is balanced at a position where the pressure of the fuel flowing in from the inlet 24 (the discharge pressure of the feed pump 2) and the fuel pressure of the damper chamber 29 + the reaction force of the spring 23 are balanced. The discharge pressure of the feed pump 2 is adjusted to a predetermined pressure according to the valve opening position of the piston 22 with respect to the hole 26.
Here, when an abnormally excessive negative pressure is generated at the inlet of the feed pump 2 or when air is mixed into the fuel sucked into the feed pump 2, the discharge pressure of the feed pump 2 becomes unstable. Repeats reciprocating motion with large amplitude.

On the other hand, in the regulating valve 4 shown in the first embodiment, since the positive pressure fuel is filled from the cam chamber 19 of the high pressure pump 3 to the damper chamber 29 via the fuel passage 27, the intake side of the feed pump 2 is used. Even when an excessive negative pressure is generated, the damper chamber 29 does not become a negative pressure, and the positive pressure can always be maintained. For this reason, the fuel pressure in the damper chamber 29 becomes higher when compared with the conventional regulating valve 120 (conventional product) shown in FIG. 12 (see FIG. 3).
Further, even when air is mixed into the fuel sucked into the feed pump 2, the amount of air mixed into the fuel in the damper chamber 29 can be reduced compared to the conventional product because the fuel pressure in the damper chamber 29 is increased (see FIG. 4).

As a result, the damper effect of the damper chamber 29 is improved with respect to the reciprocating motion of the piston 22, so that an excessive lift of the piston 22 can be suppressed and the discharge pressure of the feed pump 2 can be stabilized quickly.
Further, the regulating valve 4 of the present embodiment does not need to reduce the opening area of the vent hole 28 in order to enhance the damper effect of the damper chamber 29, and may be the same as the conventional product, so the response of the regulating valve 4 Will not be damaged.

FIG. 5 is a schematic diagram illustrating the configuration of the fuel injection pump 1 according to the second embodiment.
In the fuel injection pump 1 of the present invention, the fuel overflowing from the cam chamber 19 of the high-pressure pump 3 returns to the fuel tank 6 through the overflow passage 20, so that the cam chamber 19 and the overflow passage 20 are located inside the fuel tank 6. Is maintained at a pressure equivalent to (for example, atmospheric pressure). Therefore, by connecting the breathing hole 28 of the regulator valve 4 to the overflow passage 20 by the fuel passage 30, the damper chamber 29 is filled with positive pressure fuel as in the first embodiment. An effect improves and the excessive lift of piston 22 can be controlled.

FIG. 6 is a schematic diagram illustrating the configuration of the fuel injection pump 1 according to the third embodiment.
The fuel injection pump 1 shown in the third embodiment is fed with the fuel passage 27 described in the first embodiment, that is, the fuel passage 27 that connects the breathing hole 28 of the regulating valve 4 to the cam chamber 19 of the high-pressure pump 3. This is an example in which a throttle passage 31 that communicates between the discharge side of the pump 2 and the damper chamber 29 is provided. The throttle passage 31 is provided with an orifice 32 in the middle of the passage, and connects the feed gallery 18 and the fuel passage 27.
According to the present embodiment, not only the fuel pressure in the cam chamber 19 but also the discharge pressure of the feed pump 2 is introduced into the damper chamber 29 via the throttle passage 31, so that the configuration described in the first embodiment is compared. In addition, since the fuel pressure in the damper chamber 29 is increased, the damper effect of the damper chamber 29 is further improved.

FIG. 7 is a schematic diagram illustrating the configuration of the fuel injection pump 1 according to the fourth embodiment.
The fuel injection pump 1 shown in the fourth embodiment is an example in which the throttle passage 31 described in the third embodiment is formed in the piston 22 of the regulating valve 4. That is, as shown in FIG. 7, the throttle passage 31 is provided through the piston 22 so that the inflow port 24 and the damper chamber 29 communicate with each other. In this case, since it is not necessary to form the throttle passage 31 in the housing body of the fuel injection pump 1, the processing of the throttle passage 31 is easy.

FIG. 8 is a schematic diagram illustrating the configuration of the fuel injection pump 1 according to the fifth embodiment.
The fuel injection pump 1 shown in the fifth embodiment is provided with the discharge of the feed pump 2 in addition to the fuel passage 30 described in the second embodiment, that is, the fuel passage 30 that connects the breathing hole 28 of the regulating valve 4 to the overflow passage 20. This is an example in which a throttle passage 31 that communicates between the side and the damper chamber 29 is provided. The throttle passage 31 is provided with an orifice 32 in the middle of the passage, and connects the feed gallery 18 and the fuel passage 30.
According to the present embodiment, not only the fuel pressure in the overflow passage 20 but also the discharge pressure of the feed pump 2 is introduced into the damper chamber 29 via the throttle passage 31, so that the configuration compared with the configuration described in the second embodiment is used. In addition, since the fuel pressure in the damper chamber 29 is increased, the damper effect of the damper chamber 29 is further improved.

FIG. 9 is a schematic diagram illustrating the configuration of the fuel injection pump 1 according to the sixth embodiment.
The fuel injection pump 1 shown in the sixth embodiment is an example in which the throttle passage 31 described in the fifth embodiment is formed in the piston 22 of the regulating valve 4. That is, as shown in FIG. 9, the throttle passage 31 is provided through the piston 22, thereby connecting the inlet 24 and the damper chamber 29. In this case, since it is not necessary to form the throttle passage 31 in the housing body of the fuel injection pump 1, the processing of the throttle passage 31 is easy.

FIG. 10 is a schematic diagram illustrating the configuration of the fuel injection pump 1 according to the seventh embodiment.
The fuel injection pump 1 shown in the seventh embodiment is an example in which a fuel passage 33 that connects the breathing hole 28 of the regulating valve 4 to the fuel tank 6 is provided. That is, in Examples 2, 5, and 6 described above, the fuel passage 30 that connects the breathing hole 28 to the overflow passage 20 is provided, but in this embodiment, the breathing hole 28 is not connected to the overflow passage 20. A fuel passage 33 connected to the linear fuel tank 6 is provided. Thereby, since the positive pressure (for example, atmospheric pressure) in the fuel tank 6 is introduced into the damper chamber 29, the damper effect of the damper chamber 29 is improved and the piston is improved as in the configuration described in the second embodiment. 22 excess lift can be suppressed.
In addition to the fuel passage 33, the throttle passage 31 described in the fifth or sixth embodiment can be provided. Although the throttle passage 31 shown in FIG. 10 connects the feed gallery 18 and the fuel passage 33, the throttle passage 31 can be formed in the piston 22 as in the sixth embodiment.

FIG. 11 is a cross-sectional view of the fuel injection pump 1 according to the eighth embodiment.
In the first embodiment, the fuel passage 27 that connects the breathing hole 28 of the regulating valve 4 to the cam chamber 19 of the high-pressure pump 3 has been described. This fuel passage 27 is, for example, as shown in FIG. It can be formed in the housing body 34 of the injection pump 1. The regulating valve 4 is attached to the housing main body 34 via a seal member 35, and the seal member 35 seals between the breathing hole 28 and the suction side of the feed pump 2 in a liquid-tight manner.

It is a schematic diagram which shows the structure of a fuel injection pump (Example 1). It is sectional drawing of a regulating valve. It is a graph which shows the pressure change of a damper chamber with respect to the lift amount of a piston. It is a figure which shows the ratio of the air contained in the fuel of a damper chamber. (Example 2) which is a schematic diagram which shows the structure of a fuel injection pump. (Example 3) which is a schematic diagram which shows the structure of a fuel injection pump. (Example 4) which is a schematic diagram which shows the structure of a fuel injection pump. (Example 5) which is a schematic diagram which shows the structure of a fuel-injection pump. (Example 6) which is a schematic diagram which shows the structure of a fuel injection pump. (Example 7) which is a schematic diagram which shows the structure of a fuel injection pump. (Example 8) which is sectional drawing of a fuel-injection pump. It is a schematic diagram which shows the structure of a fuel injection pump (prior art).

Explanation of symbols

1 Fuel Injection Pump 2 Feed Pump 4 Regulating Valve 5 Cam Shaft (Drive Shaft)
6 Fuel tank (pressure system)
8 Cylinder 9 Plunger 10 Eccentric cam (cam means)
12 Cam ring (cam means)
19 Cam chamber (pressure system)
20 Overflow passage (pressure system)
21 Valve body (body)
22 Piston 24 Inlet 26 Relief hole 27 Fuel passage (Example 1, 3, 4)
28 Ventilation holes 29 Damper chamber 30 Fuel passage (Examples 2, 5 and 6)
31 Restriction passage 32 Orifice 33 Fuel passage (Example 7)

Claims (6)

A feed pump that pumps up and discharges fuel from the fuel tank, cam means that converts the rotational motion of the drive shaft driven by the internal combustion engine into reciprocating motion, and the reciprocating motion of the cam means is transmitted to reciprocate inside the cylinder. A fuel injection pump configured to reciprocate the plunger so that fuel delivered by the feed pump is sucked into the cylinder, pressurizes the sucked fuel, and pumps the fuel to the outside. Used in the injection device,
A body having an inlet connected to the discharge side of the feed pump and a relief hole connected to the suction side of the feed pump;
A piston that is inserted into the body and receives the discharge pressure of the feed pump introduced from the inflow port and moves inside the body;
In a regulating valve that regulates the discharge pressure of the feed pump to a predetermined pressure according to the valve opening position of the piston with respect to the relief hole,
A damper chamber formed on the counter-flow inlet side of the piston inside the body;
An opening on a side surface of the body forming the damper chamber, and a breathing hole through which fuel in the damper chamber enters and exits according to the behavior of the piston,
The regulator valve is characterized in that the damper chamber communicates with a pressure system having a positive fuel pressure lower than the discharge pressure of the feed pump through a fuel passage connected to the breathing hole. The regulated valve according to claim 1,
The cam means is housed inside, a cam chamber in which a part of the fuel discharged from the feed pump is supplied as lubricating oil for the cam means, and the fuel overflowing from the cam chamber returns to the fuel tank. Used in a fuel injection device having an overflow passage
The regulator valve is characterized in that the damper chamber communicates with the cam chamber via a fuel passage connected to the breathing hole. The regulated valve according to claim 1,
The cam means is housed inside, a cam chamber in which a part of the fuel discharged from the feed pump is supplied as lubricating oil for the cam means, and the fuel overflowing from the cam chamber returns to the fuel tank. Used in a fuel injection device having an overflow passage
The regulating valve is characterized in that the damper chamber communicates with the overflow passage through a fuel passage connected to the breathing hole. The regulated valve according to claim 1,
The regulator valve, wherein the damper chamber communicates with the fuel tank via a fuel passage connected to the breathing hole. In any one of the regulating valves according to claims 1 to 4,
The regulator valve is characterized in that the damper chamber communicates with a discharge side of the feed pump through a throttle passage having an orifice. The regulated valve according to claim 5,
The restricting passage is formed by penetrating the piston, and the inlet and the damper chamber communicate with each other through the restricting passage.