JP6948891B2 - Fuel pump device - Google Patents

Description

The present invention relates to a fuel pump device, and more particularly to a fuel pump device including a mechanical feed pump that sucks fuel from a fuel tank.

Conventionally, as a device for supplying fuel to an internal combustion engine such as a diesel engine, a fuel pump device including a mechanical feed pump for sucking fuel from a fuel tank is known (see, for example, Patent Document 1).

The feed pump sucks up the fuel stored in the fuel tank through a low-pressure fuel passage provided with an orifice, and then supplies the fuel to the fuel injection pump through a fuel filter.

The suction side of the mechanical feed pump becomes negative pressure during its operation, and a pressure difference is created between the atmospheric pressure acting on the fuel in the fuel tank and the negative pressure, and this pressure difference causes the direction from the fuel tank to the feed pump. Fuel is sucked up.

A fuel injection pump is connected to the downstream side of the feed pump. The fuel injection pump is attached to the engine and pressurizes and pumps fuel by transmitting the driving force from the drive shaft of the engine to the camshaft of the fuel injection pump.

Here, as shown in FIG. 5, in a fuel pump device including a mechanical feed pump, the flow rate of fuel supplied from the feed pump to the fuel injection pump is the maximum requirement required by the fuel injection pump. It must be set so as to be greater than the flow rate f0 and less than the allowable passing flow rate of the fuel filter.

Japanese Unexamined Patent Publication No. 2013-167163

Since the mechanical feed pump is driven in synchronization with the rotation speed of the fuel injection pump, it is supplied from the feed pump in proportion to the increase in the rotation speed of the drive shaft of the engine, as shown in FIG. It has the characteristic that the flow rate of the fuel is also increased (see the FP theoretical discharge amount in FIG. 5).

When the rotation speed of the drive shaft of the engine exceeds a certain level, the fuel tank and feed are used to limit the flow rate of fuel so that the flow rate of fuel supplied from the feed pump does not exceed the allowable passing flow rate of the fuel filter. The low-pressure fuel passage between the pump and the low-pressure fuel passage is provided with the above-mentioned orifice.

Further, since the pressure difference changes depending on the atmospheric pressure, when the atmospheric pressure is low, the pressure difference becomes smaller than when the atmospheric pressure is high, and the flow rate of the fuel sucked up by the feed pump becomes smaller. On the contrary, when the atmospheric pressure is high, the pressure difference becomes larger than when the atmospheric pressure is low, and the flow rate of the fuel sucked up by the feed pump increases. For example, in high altitude areas, the atmospheric pressure is relatively lower than in low altitude flat areas, and the pressure difference between the atmospheric pressure acting on the fuel in the fuel tank and the negative pressure generated on the suction side of the feed pump. Is reduced, and the flow rate of fuel sucked up by the feed pump is reduced. FIG. 5 shows an example of the characteristics of the flow rate (f2) when the atmospheric pressure is high and the flow rate (f1) when the atmospheric pressure is low in the combination of the conventional orifice and the mechanical feed pump.

As described above, the flow rate of the fuel supplied from the feed pump to the fuel injection pump must be set to be larger than the maximum required flow rate f0 required by the fuel injection pump. According to this, the flow rate of the fuel supplied from the feed pump when the assumed atmospheric pressure is the lowest is set to be larger than the maximum required flow rate f0 of the fuel injection pump, but as a result, the minimum required flow rate f0. As the atmospheric pressure becomes higher than the atmospheric pressure, the flow rate of the fuel supplied from the feed pump becomes larger than the maximum required flow rate f0 of the fuel injection pump.
As described above, in the fuel pump device provided with the conventional orifice and the mechanical feed pump, more fuel than necessary is supplied from the feed pump to the fuel injection pump in most atmospheric pressure regions. Since the excessively supplied fuel is returned to the fuel tank through the fuel return path, there are problems such as deterioration of fuel efficiency and increase in fuel temperature.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel pump device including a mechanical feed pump that does not supply an excessive amount of fuel due to atmospheric pressure conditions.

In order to achieve the above object, the fuel pump device of the present invention is a machine that sucks up the fuel by the pressure difference between the atmospheric pressure acting on the fuel stored in the fuel tank and the negative pressure generated on the downstream side of the fuel tank. A type feed pump, a fuel injection pump that pumps the fuel supplied from the mechanical feed pump at a high pressure, and a flow control mechanism arranged in a fuel supply path between the fuel tank and the mechanical feed pump. The flow control mechanism is characterized by having a fuel throttle adjusting passage whose fuel passage cross-sectional area changes according to the atmospheric pressure acting on the fuel.

In the fuel pump device according to the present invention, the negative pressure is a negative pressure generated on the fuel suction side of the mechanical feed pump during operation of the mechanical feed pump.

In the fuel pump device according to the present invention, the flow rate control mechanism is characterized in that the fuel passage cross-sectional area of the fuel throttle adjusting passage is increased when the atmospheric pressure acting on the fuel drops.

In the fuel pump device according to the present invention, the flow rate control mechanism includes a hollow tubular body whose inside is a passage for the fuel and a moving body that moves inside the tubular body. The fuel passage cross-sectional area of the fuel throttle adjusting passage changes based on the movement.

In the fuel pump device according to the present invention, the flow control mechanism further includes a spring element in the tubular body, and the force of the atmospheric pressure acting on the fuel, the negative pressure, and the elastic force of the spring element. It is characterized in that the moving body moves due to the balance.

The fuel pump device according to the present invention is characterized in that an expansion portion is provided on the inner peripheral surface of the hollow portion of the tubular body, and the fuel throttle adjusting passage is formed between the moving body and the expansion portion. And.

In the fuel pump device according to the present invention, a through hole is provided on the side surface of the tubular body to the hollow portion and is a passage for the fuel, and the fuel throttle adjusting passage is formed between the moving body and the through hole. It is characterized by being formed between them.

According to the present invention, it is possible to realize a fuel pump device including a mechanical feed pump in which excessive fuel is not supplied due to atmospheric pressure conditions.

It is a schematic conceptual diagram which shows the whole structure of the common rail system which concerns on embodiment of this invention. It is sectional drawing which shows the flow rate control mechanism in 1st Embodiment of this invention. It is sectional drawing which shows the state under the flat ground condition about the flow rate control mechanism in 1st Embodiment of this invention. It is sectional drawing which shows the state under the high altitude condition about the flow rate control mechanism in 1st Embodiment of this invention. It is a diagram which shows the flow rate characteristic of the fuel supplied from a feed pump in relation to the rotation speed of the drive shaft of an engine in a conventional fuel pump device. In the fuel pump device of the present invention, it is a diagram which shows the flow rate characteristic of the fuel supplied from a feed pump in relation to the rotation speed of the drive shaft of an engine. It is sectional drawing which shows the flow rate control mechanism in 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view showing a state of the flow rate control mechanism according to the second embodiment of the present invention under flat ground conditions. It is sectional drawing which shows the state under the high altitude condition about the flow rate control mechanism in 2nd Embodiment of this invention.

<First Embodiment>
Hereinafter, the first embodiment of the present invention will be specifically described with reference to the drawings. Here, an example of a fuel pump device including a mechanical feed pump used in a common rail system will be described, but the present invention is limited to a fuel pump device including a mechanical feed pump used in a common rail system. It can also be used for, for example, a row pump, a distribution pump, or the like.

<Overall configuration of common rail system>
As shown in FIG. 1, the common rail system 10 is mainly used as a system for injecting fuel into the cylinder of a diesel engine.

The common rail system 10 includes a fuel tank 20, a fuel pump device 30, a common rail 90, a plurality of injectors (not shown), and the like as main components.

The fuel tank 20 stores light oil, which is a fuel for a diesel engine, and one end of a low-pressure fuel passage 11 as a fuel supply passage and one end of a fuel return passage 12 are connected to the fuel tank 20.

The fuel return passage 12 is a fuel that has flowed out to a first return passage 12a arranged on the downstream side of an injector (not shown), a fuel that has flowed out to a second return passage 12b arranged on the downstream side of the pressure control valve 14, and an overflow described later. The fuel that has flowed out to the third return path 12c and the fourth return path 12d arranged on the downstream side of the valve 80 and the fuel that has flowed out to the fifth return path 12e arranged on the downstream side of the bearing 78 merge, and these fuels Is a flow path for returning the fuel to the fuel tank 20. Atmospheric pressure P2 acts on the fuel stored in the fuel tank 20.

The fuel pump device 30 includes a flow control mechanism 40, a feed pump unit 50 as a mechanical feed pump, a fuel metering unit 60, a fuel injection pump 70, an overflow valve 80, and the like as components.

The flow rate control mechanism 40 is a mechanical structure having a fuel throttle adjusting passage 46 having a throttle having a variable fuel passage cross-sectional area, and is provided between the fuel tank 20 and the feed pump unit 50, if necessary. It has a fuel throttle passage 47 having a fixed cross-sectional area of the fuel passage. The detailed configuration of the flow rate control mechanism 40 will be described later.

The feed pump unit 50 is a mechanical feed pump that sucks fuel from the fuel tank 20 via the flow control mechanism 40 and supplies the fuel to the fuel injection pump 70.

The feed pump unit 50 may be of any type as long as it is a mechanical type, and an example thereof is a so-called gear pump. This gear pump is, for example, a circumscribed gear type. The gear pump is not limited to the circumscribed gear type, and may be, for example, an inscribed gear type.

A fuel filter 13 is provided between the feed pump unit 50 and the fuel injection pump 70. The fuel filter 13 is a filter that collects foreign matter mixed in the fuel supplied from the feed pump unit 50 to the fuel injection pump 70.

The fuel metering unit 60 is arranged between the fuel filter 13 and the fuel injection pump 70. The fuel metering unit 60 is a proportionally controlled valve mechanism that adjusts the flow rate of fuel supplied to the fuel injection pump 70.

The fuel injection pump 70 is a pump that increases the pressure of fuel and sends it to the common rail 90, and is connected to the common rail 90 by a high-pressure fuel passage 79 for pumping the high-pressure fuel.

The fuel injection pump 70 includes a cam chamber 71a, a camshaft 72, a plunger 74 that moves in the vertical direction according to the rotation of the camshaft 72, and the like. The fuel supplied to the pressurizing chamber 76 is increased in pressure and supplied to the common rail 90.

Most of the fuel sent from the feed pump unit 50 that has not been increased in pressure is supplied to the cam chamber 71a of the fuel injection pump 70 via the second inflow passage 11b to lubricate the mechanical components in the cam chamber 71a. do. The fuel lubricated in the cam chamber 71a flows out of the fuel injection pump 70 through the outflow passage 11c, the fifth return passage 12e arranged on the downstream side of the bearing 78, and the like. The fuel spilled from the outflow passage 11c enters the overflow valve 80, then passes through the third return passage 12c or the fourth return passage 12d and exits from the overflow valve 80, and exits from the first return passage 12a, the second return passage 12b, and the fifth return passage. The fuel from the return passage 12e merges with the fuel return passage 12 and is returned to the fuel tank 20. The overflow valve 80 is a pressure adjusting valve that regulates the pressure of the fuel supplied to the cam chamber 71a of the fuel injection pump 70 within a constant pressure range.

The common rail 90 stores the high-pressure fuel pumped from the fuel injection pump 70 via the high-pressure fuel passage 79, and with respect to a plurality of injectors (not shown) connected via the high-pressure fuel passage 79. Supply high pressure fuel.

A rail pressure sensor (not shown) is attached to the common rail 90, and a pressure control valve 14 is attached on the second return passage 12b connected to the common rail 90. The rail pressure control of the common rail 90 is performed using at least one of the fuel metering unit 60 and the pressure control valve 14.

<Flow control mechanism>
Next, a specific configuration of the flow rate control mechanism 40 according to the first embodiment will be described with reference to FIG.

The flow rate control mechanism 40 is provided on the line of the low pressure fuel passage 11 between the fuel tank 20 and the feed pump unit 50. The flow rate control mechanism 40 includes an eyebolt 41, an eye joint 42, an orifice plate 43 which is a moving body as a reciprocating member, and a spring 44 as an elastic member.

The eyebolt 41 is a bottomed tubular body, and has a cylindrical main body 41a in which one end in the longitudinal direction is closed, and a disk-shaped spring provided at the other end of the main body 41a. It has a receiving portion 41b.

The main body 41a of the eyebolt 41 is formed with a first through hole 41e that penetrates the main body 41a in the radial direction.

At the center of the spring receiving portion 41b, a second through hole 41f is formed as an outflow opening that penetrates along the longitudinal direction of the main body portion 41a. A male screw portion is formed in the range from the spring receiving portion 41b to the vicinity of the first through hole 41e in the outer peripheral surface 41c of the main body portion 41a.

A hollow portion having an inner peripheral surface 41d is formed inside the eyebolt 41, and the hollow portion is formed in a substantially cylindrical shape. However, the inner peripheral surface 41d has a first through hole 41e and a first through hole 41e in the longitudinal direction. A so-called groove-shaped expansion portion 41g is formed in a certain range between the two through holes 41f and the vicinity of the first through hole 41e.

The expansion portion 41g is defined by a wall surface portion 41j that expands in a direction orthogonal to the longitudinal direction of the eyebolt 41 and an inclined portion 41k that is inclined from an end portion on the outer peripheral side of the wall surface portion 41j. The inclined portion 41k is formed so that the inner peripheral surface 41d is gradually reduced in diameter in the axial direction of the eyebolt 41 toward the second through hole 41f.

In this case, the expansion portion 41g is formed by an inclined portion 41k that is continuous over the circumferential direction of the inner peripheral surface 41d of the main body portion 41a, but is not limited to this, and is not limited to this, and the expansion portion 41g is formed with respect to the inner peripheral surface 41d of the main body portion 41a. It may be formed by a partially inclined portion 41k formed intermittently in the circumferential direction.

The orifice plate 43 is a disk-shaped member provided so as to be movable in the longitudinal direction of the eyebolt 41 in the hollow portion of the eyebolt 41, and has a communication hole 43a penetrating in the longitudinal direction of the eyebolt 41 in the center thereof. The diameter of the communication hole 43a is smaller than the diameter of the conventional orifice. A spring 44 is fixed to the lower surface of the orifice plate 43, and the other end of the spring 44 is fixed to the spring receiving portion 41b. The spring 44 urges the orifice plate 43 in the direction from the second through hole 41f toward the first through hole 41e.

The orifice plate 43 has an internal pressure P3 acting on the surface on the side of the first internal space 41h communicating with the fuel tank 20 through the low pressure fuel passage 11, the first through hole 41e, and the like, and the pressure P1 acting on the opposite surface. It is held in a position where the restoring force of the spring 44 and the restoring force of the spring 44 are balanced. For example, when the vehicle moves from a flat ground to a high ground and the atmospheric pressure P2 acting on the fuel tank 20 decreases, the internal pressure P3 decreases in accordance with the decrease in the atmospheric pressure P2. Due to this decrease in the internal pressure P3, the balance of forces before and after the orifice plate 43 is changed, and the orifice plate 43 is displaced toward the first through hole 41e.

In the flow rate control mechanism 40 having such a configuration, the male screw portion provided on the outer peripheral surface 41c of the eyebolt 41 is screwed into the female screw portion provided on the suction side pipeline 52 of the feed pump unit 50. At this time, the flange portion 41n formed on the outer circumference of the eyebolt 41 is screwed until it comes into contact with the upper surface of the eye joint 42. In this way, the eye joint 42 is sandwiched between the flange portion 41n of the eyebolt 41 and the upper surface of the feed pump unit 50, the flow rate control mechanism 40 is attached to the feed pump unit 50, and the second through hole 41f is formed. It communicates with the suction side pipeline 52 of the feed pump unit 50. The suction side pipeline 52 is a pipeline on the fuel suction side of the feed pump unit 50, and a negative pressure is generated in the suction side pipeline 52 during the operation of the feed pump unit 50.

<Operation and effect>
The operation and effect of the flow rate control mechanism 40 in the first embodiment will be described with reference to FIGS. 3, 4, and 6.

In the common rail system 10, when the feed pump unit 50 is driven, a pressure P1 (negative pressure) is generated in the second internal space 41 m of the eyebolt 41 of the flow rate control mechanism 40 communicating with the suction side pipeline 52. On the other hand, an internal pressure P3 corresponding to the atmospheric pressure P2 acting on the fuel in the fuel tank 20 is generated in the first internal space 41h of the eyebolt 41. Since the internal pressure P3 is higher than the pressure P1, the fuel flows in the direction from the first internal space 41h to the second internal space 41m. That is, the fuel in the fuel tank 20 flows in the direction of the feed pump unit 50.

FIG. 3 shows a state in which the orifice plate 43 of the flow rate control mechanism 40 is held in a place where the atmospheric pressure P2 is high. A place where the atmospheric pressure is high is, for example, a flat land and a place where the altitude is low. In this case, it is preferable that the surface of the orifice plate 43 on the side of the second internal space 41 m is located near the intersection 41z between the inclined portion 41k of the eyebolt 41 and the cylindrical portion of the inner peripheral surface 41d.
The communication hole 43a of the orifice plate 43 constitutes a fuel throttle passage 47 which is a throttle having a fixed fuel passage cross-sectional area, and the distance between the outer peripheral surface and the inner peripheral surface 41d of the orifice plate 43 is a throttle having a variable fuel passage cross-sectional area. At this point, the distance between the outer peripheral surface and the inner peripheral surface 41d of the orifice plate 43 is extremely narrow, so that most of the fuel from the first internal space 41h has a communication hole 43a. It passes through and flows to the second internal space 41 m. The diameter of the communication hole 43a is set to a size that is smaller than that of the conventional orifice and that can secure a flow rate that exceeds the maximum injection flow rate f0 of the fuel injection pump. As a result, as shown in FIG. 6, the flow rate f3 of the fuel supplied from the feed pump unit 50 to the fuel injection pump 70 in a place where the atmospheric pressure is high is higher than the flow rate f2 of the fuel when the flow rate control mechanism 40 is not provided. And the wasteful fuel supply is reduced.

FIG. 4 shows a state in which the orifice plate 43 of the flow rate control mechanism 40 is held in a place where the atmospheric pressure P2 is lower than that in FIG. A place where the atmospheric pressure is low is, for example, a highland and a place where the altitude is high. Since the atmospheric pressure P2 is low, the internal pressure P3 is also low, and the orifice plate 43 of the flow rate control mechanism 40 moves in the direction of the first internal space 41h accordingly. Due to the movement of the orifice plate 43, the distance between the outer periphery of the orifice plate 43 and the inclined portion 41k in the expansion portion 41g which is a part of the inner peripheral surface 41d is widened, and the fuel passage cross-sectional area of the fuel throttle adjusting passage 46 is increased. Due to the decrease in the internal pressure P3 due to the decrease in the atmospheric pressure P2, the differential pressure before and after the orifice plate 43 becomes smaller, and the flow rate passing through the communication hole 43a decreases, but the flow rate passing through the fuel throttle adjusting passage 46 increases, resulting in a large result. It is possible to supply the fuel f4 equivalent to the case where the atmospheric pressure P2 is high to the fuel injection pump 70.

The orifice plate 43 moves to the side of the first internal space 41h in response to the decrease in the atmospheric pressure P2 acting on the fuel in the fuel tank 20, but the position corresponding to the assumed minimum value of the atmospheric pressure P2 is The first distance a1 formed by the upper surface of the orifice plate 43 and the wall surface portion 41j of the expansion portion 41g is longer than the second distance a2 formed by the lower surface of the orifice plate 43 and the inclined portion 41k of the expansion portion 41g. It is preferable to do so. A stopper member may be provided at the position so that the orifice plate 43 comes into contact with the orifice plate 43.

As shown in FIG. 6, even when a vehicle equipped with the common rail system moves from a flat ground to a high ground and the atmospheric pressure P2 drops, the flow control mechanism 40 operates to change the atmospheric pressure. It is not affected and the same fuel flow rate can be supplied from the feed pump unit 50 to the fuel injection pump 70.

As described above, in the fuel pump device equipped with the conventional orifice and the mechanical feed pump, more fuel than necessary is supplied from the feed pump to the fuel injection pump in most atmospheric pressure regions. By using the flow control mechanism 40, the fuel pump device 30 to which the present invention is applied prevents supplying excess fuel due to atmospheric pressure conditions, and reduces the amount of fuel returned to the fuel tank 20 via the fuel return path 12. Can be reduced. Since the fuel returned to the fuel tank 20 via the fuel return passage 12 is heated in the process of its flow, the increase in the fuel temperature can be suppressed by reducing the amount of fuel returned to the fuel tank 20. As a result, deterioration due to fuel oxidation can be suppressed. Further, since the fuel flow rate can be reduced, the low-pressure fuel passage 11 and the fuel return passage 12 do not require a pipe having a large inner diameter with a small pressure loss, and the pipe options are increased, so that cost reduction can be achieved. can.

Further, by using the flow rate control mechanism 40, the fuel pump device 30 does not need to drive the feed pump unit 50 more than necessary by the drive shaft of the engine, and the drive torque of the engine does not need to be wasted. As a result, fuel efficiency can be improved.

Further, the fuel pump device 30 can suppress the flow rate of the low-pressure fuel passing through the fuel filter 13 by using the flow rate control mechanism 40. Therefore, since the fuel filter 13 having an unnecessarily large allowable passing flow rate and unnecessarily high withstand voltage performance is not required, the size of the fuel filter 13 can be reduced, and as a result, the cost increase can be suppressed. can.

<Second embodiment>
A specific configuration of the flow rate control mechanism 40'in the second embodiment will be described with reference to FIG. 7. In FIG. 7, the same reference numerals are given to the portions corresponding to those in FIG. Hereinafter, the differences from the first embodiment will be mainly described.

In the second embodiment, as shown in FIG. 7, in addition to the first through hole 41e as the supply through hole, the eyebolt 41 is closer to one end in the longitudinal direction than the first through hole 41e. It has a third through hole 41p as a pressure forming through hole that penetrates from the outer peripheral surface 41c to the inner peripheral surface 41d at the position.

Further, the flow rate control mechanism 40'has a piston member 45 as a reciprocating member instead of the orifice plate 43 having the communication hole 43a. The internal space of the eyebolt 41 is partitioned by the piston member 45 into a first internal space 41h communicating with the third through hole 41p and a second internal space 41m communicating with the first through hole 41e. The piston member 45 is a moving body that reciprocates along the inner peripheral surface 41d of the eyebolt 41.

FIG. 8 shows a state in which the piston member 45 of the flow rate control mechanism 40'is held in a place where the atmospheric pressure P2 is high. A place where the atmospheric pressure is high is, for example, a flat land and a place where the altitude is low. In this case, the piston member 45 partially closes the first through hole 41e on the inner peripheral surface 41d of the eyebolt 41 to form a first gap s1 between the main body portion 41a of the eyebolt 41 and the piston member 45, and fuel. Passes through the gap s1 and flows to the second internal space 41 m. The size of the first gap s1 is set to be smaller than that of the conventional orifice and to a size that can secure a flow rate exceeding the maximum injection flow rate f0 of the fuel injection pump. As a result, as shown in FIG. 6, the flow rate f3 of the fuel supplied from the feed pump unit 50 to the fuel injection pump 70 in a place where the atmospheric pressure is high is the flow rate f2 of the fuel when the flow rate control mechanism 40'is not provided. Compared to this, the supply of wasted fuel is reduced.
The portion of the first through hole 41e that is not blocked by the piston member 45 constitutes the fuel throttle adjusting passage 46, which is a throttle having a variable fuel passage cross-sectional area.

FIG. 9 shows a state in which the piston member 45 of the flow rate control mechanism 40'is held in a place where the atmospheric pressure P2 is lower than that in FIG. A place where the atmospheric pressure is low is, for example, a highland and a place where the altitude is high. Since the atmospheric pressure P2 is low, the internal pressure P3 is also low, and the piston member 45 of the flow rate control mechanism 40'moves in the direction of the first internal space 41h accordingly. Together with the piston member 45, the above-mentioned first gap s1 is expanded to the second gap s2, and the fuel passage cross-sectional area of the fuel throttle adjusting passage 46 becomes large. Due to the decrease in the internal pressure P3 due to the decrease in the atmospheric pressure P2, the differential pressure becomes smaller, but the fuel passage cross-sectional area of the fuel throttle adjusting passage 46 increases, so the fuel f4 equivalent to the case where the atmospheric pressure P2 is high is injected. It becomes possible to supply to the pump 70.

The piston member 45 moves to the side of the first internal space 41h in response to a decrease in the atmospheric pressure P2 acting on the fuel in the fuel tank 20, but the position corresponding to the assumed minimum value of the atmospheric pressure P2 is It is preferable that the upper surface of the piston member 45 does not reach the third through hole 41p. A stopper member may be provided at the position so that the piston member 45 comes into contact with the piston member 45.

As described above, in the fuel pump device equipped with the conventional orifice and the mechanical feed pump, more fuel than necessary is supplied from the feed pump to the fuel injection pump in most atmospheric pressure regions. By using the flow control mechanism 40, the fuel pump device 30 to which the present invention is applied prevents supplying excess fuel due to atmospheric pressure conditions, and reduces the amount of fuel returned to the fuel tank 20 via the fuel return path 12. Can be reduced.
Since the fuel returned to the fuel tank 20 via the fuel return passage 12 is heated in the process of its flow, the increase in the fuel temperature can be suppressed by reducing the amount of fuel returned to the fuel tank 20. As a result, deterioration due to fuel oxidation can be suppressed. Further, since the fuel flow rate can be reduced, the low-pressure fuel passage 11 and the fuel return passage 12 do not require a pipe having a large inner diameter with a small pressure loss, and the pipe options are increased, so that cost reduction can be achieved. can.

Further, by using the flow rate control mechanism 40'in the fuel pump device 30, it is not necessary to drive the feed pump unit 50 more than necessary by the drive shaft of the engine, and the drive torque of the engine is not wasted. As a result, fuel efficiency can be improved.

Further, the fuel pump device 30 can suppress the flow rate of the low-pressure fuel passing through the fuel filter 13 by using the flow rate control mechanism 40'. Therefore, since the fuel filter 13 having an unnecessarily large allowable passing flow rate and unnecessarily high withstand voltage performance is not required, the size of the fuel filter 13 can be reduced, and as a result, the cost increase can be suppressed. can.

<Other embodiments>
In the first embodiment, the expansion portion 41g is formed on the inner peripheral surface 41d of the eyebolt 41, and the orifice plate 43 and the spring 44 are arranged in the eyebolt 41. The spring 44) can be provided at an arbitrary position as long as it is on the upstream side of the feed pump unit 50.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the common rail system 10 according to the above embodiment, and all aspects included in the concept of the present invention and the scope of claims. including. In addition, each configuration may be selectively combined as appropriate so as to achieve at least a part of the above-mentioned problems and effects. For example, the shape, material, arrangement, size, etc. of each component in the above embodiment can be appropriately changed depending on the specific usage mode of the present invention.

The high-pressure pump device and fuel supply system of the present invention can be used not only in the field of diesel engines for vehicles such as automobiles, but also in the field of industrial diesel engines such as agricultural machinery, construction machinery, and ships. ..

10 Common rail system 11 Low pressure fuel passage 11a First inflow passage 11b Second inflow passage 11c Outflow passage 12 Fuel return passage 12a First return passage 12b Second return passage 12c Third return passage 12d Fourth return passage 12e Fifth return passage 13 Fuel filter 14 Pressure control valve 20 Fuel tank 30 Fuel pump device 40, 40'Flow control mechanism 41 Eyebolt 41a Main body 41b Spring receiving part 41c Outer peripheral surface 41d Inner peripheral surface 41e First through hole 41f Second through hole 41g Expansion part 41h 1st internal space 41j Wall surface 41k Inclined 41m 2nd internal space 41n Flange 41p 3rd through hole 41z Intersection 42 Eye joint 43 orifice plate 43a Communication hole 44 Spring 45 Piston member 46 Fuel throttle adjustment passage 47 Fuel throttle passage 50 Feed pump unit 52 Suction side pipeline 60 Fuel metering unit 70 Fuel injection pump 71a Cam chamber 72 Cam shaft 74 Plunger 76 Pressurization chamber 78 Bearing 79 High pressure fuel passage 80 Overflow valve 90 Common rail a1 First distance a2 Second distance s1 First 1 Gap s2 2nd Gap P1 Pressure, Negative pressure P2 Atmospheric pressure P3 Internal pressure

Claims (6)

A mechanical feed pump that sucks up the fuel by the pressure difference between the atmospheric pressure acting on the fuel stored in the fuel tank and the negative pressure generated on the downstream side of the fuel tank.
A fuel injection pump that pumps the fuel supplied from the mechanical feed pump at high pressure and
It is equipped with a flow control mechanism arranged in the fuel supply path between the fuel tank and the mechanical feed pump.
The flow rate control mechanism
A fuel throttle adjustment passage whose cross-sectional area for passing fuel changes according to the atmospheric pressure acting on the fuel , and
A hollow cylinder whose inside is a passage for the fuel,
A moving body that moves inside the tubular body and
With
A fuel pump device characterized in that the fuel passage cross-sectional area of the fuel throttle adjusting passage changes based on the movement of the moving body. The fuel pump device according to claim 1, wherein the negative pressure is a negative pressure generated on the fuel suction side of the mechanical feed pump during operation of the mechanical feed pump. The flow rate control mechanism
The fuel pump device according to claim 1 or 2, wherein the fuel passage cross-sectional area of the fuel throttle adjusting passage is increased when the atmospheric pressure acting on the fuel is lowered. The flow rate control mechanism
A spring element is further provided in the cylindrical body,
It said atmospheric pressure acting on the fuel, the negative pressure, by the balance of forces between the elastic force of the spring element, the fuel pump device according to claim 1, wherein the moving body is thus being moved. An expansion portion is provided on the inner peripheral surface of the hollow portion of the tubular body.
The fuel pump device according to claim 1 , wherein the fuel throttle adjusting passage is formed between the moving body and the expansion portion. A through hole that penetrates to the hollow portion of the cylindrical body and is a passage for the fuel is provided on the side surface of the tubular body.
The fuel pump device according to claim 1 , wherein the fuel throttle adjusting passage is formed between the moving body and the through hole.

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