JP2000027753A - Fluid pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a feed function for leading the fluid into a pump chamber without increasing dimension of a pump and without increasing the number of structural parts in a fluid pump. SOLUTION: This fluid pump is provided with a first and a second pump mechanisms 22, 24. Each pump mechanism 22, 24 is provided with a plunger 28 and a lifter 36. The lifter 36 and the plunger 28 of each pump mechanism 22, 24 are integrally reciprocated in the phase condition opposite to that of the other pump mechanism. A feed pump chamber 38 formed by the lifter 36 and the plunger 28 is enlarged and shrunken synchronously with a high-pressure pump chamber 30. A fuel passage for connecting the feed pump chamber 38 of each pump mechanism 22, 24 and the high-pressure pump chamber 30 of the other pump mechanism is provided. When the feed pump chamber 38 is shrunken, fuel is fed by the pressure to the high-pressure pump chamber 30 of the other driving pump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluid pump, and more particularly, to a fluid pump having a feed function for introducing a fluid into a pump chamber.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. Hei 6-24913
As disclosed in No. 4, a fluid pump for pumping a fluid from a fluid tank is known. The above-mentioned conventional fluid pump,
A plunger slidably disposed inside the cylinder, a cam mechanism for reciprocating the plunger, and a pump chamber that expands and contracts in accordance with the reciprocation of the plunger.
The fluid sucked into the pump chamber when the pump chamber is expanded is discharged when the pump chamber is reduced, so that the fluid is pumped.

The above-mentioned conventional fluid pump also includes a separate low-pressure supply pump (feed pump) for introducing a fluid from a fluid tank into a pump chamber. Since the fluid is introduced into the pump chamber by the feed pump, a pressure loss when sucking the fluid from the fluid tank is prevented, and the fluid pump can exhibit a high pumping ability.

[0004]

As described above, the conventional fluid pump has a structure in which a feed pump for introducing fuel into a pump chamber is provided separately. For this reason, inconveniences such as an increase in the size of the pump and an increase in cost due to an increase in the number of components are caused. The present invention has been made in view of the above points, and provides a fluid pump capable of realizing a feed function for introducing a fluid into a pump chamber without increasing the size of the pump or increasing the number of parts. The purpose is to do.

[0005]

The above object is achieved by the present invention.
A fluid pump including a reciprocating plunger and a pump chamber that expands and contracts in accordance with the reciprocating motion of the plunger, wherein the pump chamber expands in accordance with the reciprocating motion of the plunger. And a first pump that supplies a fluid supplied from an external fluid source to the feed pump chamber when the feed pump chamber is expanded, when the pump chamber is expanded. This is achieved by a fluid pump including a transport mechanism and a second fluid transport mechanism that supplies a fluid in the feed pump chamber to the pump chamber when the feed pump chamber is reduced.

The above object is also achieved by a reciprocating plunger, a first pump chamber that expands and contracts in accordance with the reciprocation of the plunger, and a second pump chamber that is formed separately from the first pump chamber. Wherein the first pump chamber of the set expands due to the reciprocation of one set of plungers, the second pump chamber of the other set shrinks, and the first pump of the set decreases. The other set of second pump chambers is configured to expand when the pump chamber is reduced, and when the second pump chamber is expanded, a fluid supplied from an external fluid source is supplied to the second pump chamber. A first fluid transport mechanism and a second fluid transport mechanism;
This is also achieved by a fluid pump including a second fluid transport mechanism that supplies a fluid in the second pump chamber to a predetermined first pump chamber when the pump chamber is reduced.

In the present invention, the second pump chamber contracts when the first pump chamber expands and expands when the first pump chamber contracts in accordance with the reciprocating motion of the plunger. The first fluid transfer mechanism supplies a fluid to the feed pump chamber when the second pump chamber expands. Further, the second fluid transfer mechanism supplies the fluid in the second pump chamber to the first pump chamber when the second pump chamber is reduced (ie, when the first pump chamber is expanded). As described above, the function (feed function) of introducing a fluid into the first pump chamber is realized by the change in the volume of the second pump chamber due to the reciprocating motion of the plunger.
It is not necessary to provide a separate feed pump in front of the pump chamber.

According to a third aspect of the present invention, there is provided a fluid pump according to the first aspect, wherein the first fluid transport mechanism communicates the feed pump chamber with the fluid source. And a flow path cut-off mechanism that switches between conduction and cut-off of the fluid passage according to the position of the plunger.

In the present invention, the flow path cutoff mechanism switches between conduction and cutoff of the fluid passage communicating with the feed pump chamber according to the position of the plunger. Therefore, the flow of the fluid into the feed pump chamber is permitted or prohibited depending on the position of the plunger, so that there is no need to provide a check valve or the like for preventing a backflow from the feed pump chamber to the fluid source side. Becomes

[0010]

FIG. 1 is a block diagram of a fluid pump according to an embodiment of the present invention. As shown in FIG. 1, the fluid pump according to the present embodiment is connected between a fuel tank 10 and a common rail 11. The common rail 11 stores fuel at a required pressure to supply fuel to a fuel injection device of the engine. In the present embodiment, the fluid pump 10 has a role of pumping the fuel from the fuel tank 10 to the common rail 11 so that the fuel in the common rail 11 is maintained at a required pressure.

As shown in FIG. 1, the fluid pump according to the present embodiment has a housing member 12. Housing member 12
Is a circular cam accommodating chamber 14 provided at the center thereof,
Further, a pair of cylindrical pump storage chambers 16 extending from the cam storage chamber 14 to the left and right sides in FIG. 1 and opening to the surface of the housing member 12 are provided. The opening of the pump housing 16 to the surface of the housing member 12 is provided with an enlarged diameter portion 16a having a larger diameter by a predetermined amount than other portions.

A cam 18 having a rectangular shape is housed in the cam housing chamber 14. The cam 18 has a circular shaft hole 18a at the center thereof. An eccentric shaft 20 is fitted into the shaft hole 18a so as to be slidable in the rotation direction. The eccentric shaft 20 is fixed to a drive motor (not shown) in a state of being eccentric from its rotation center S. The fluid pump of the present embodiment includes a first pump mechanism 22 disposed on the left side of the cam 18 in FIG. 1 and a second pump mechanism 22 disposed on the right side of FIG.
A pump mechanism 24 is provided. The first pump mechanism 22 and the second pump mechanism 24 have a substantially left-right symmetric configuration.

The first pump mechanism 22 includes a cylinder member 26
It has. The cylinder member 26 includes a main body 26a,
A cylindrical portion 26b protruding from the main body 26a. The cylinder member 26 is fixed to the housing member 12 so that the cylindrical portion 26b is housed in the pump housing chamber 16 of the housing member 12. Cylinder member 2
6 also includes a cylinder 26c whose one end is open to the end face of the cylindrical portion 26b. The other end of the cylinder 26c is sealed by a plug member 27. In the cylinder 26c,
The plunger 28 is disposed so as to be liquid-tight and slidable in the axial direction such that one end thereof protrudes from the end face of the cylindrical portion 26b. The space between the plunger 28 and the seal plug 27 inside the cylinder 26c constitutes a high-pressure pump chamber 30.

One end of the plug member 27 has a high-pressure pump chamber 30.
An axial passage 27a which is open to the other end and the other end of which is closed;
A radial passage 27b communicating with the plug 7a and opening on the outer surface of the plug member 27 is provided. A high-pressure inlet check valve 31 is provided at an opening of the passage 27 a to the high-pressure pump chamber 30. The high-pressure inlet check valve 31 allows only the flow of the fluid from the passage 27a toward the high-pressure pump chamber 30.
Further, a fuel passage described later communicates with the passage 27b.

A disc-shaped retainer 32 is provided near the tip of the plunger 28 projecting from the cylinder member 26.
Is fitted. Retainer 32 and cylinder member 26
A spring 34 is provided between the main body 26a and the main body 26a so as to surround the cylindrical portion 26b. Spring 3
4 moves the plunger 28 via the retainer 32 to the cam 18.
It is urging toward.

The first pump mechanism 22 includes a lifter 36.
It has. The lifter 36 is a cylindrical member having one end closed. The closed-side end wall of the lifter 36 (hereinafter, referred to as a lifter end wall 36a) is configured such that its central portion is higher than its peripheral portion. The lifter 36 is disposed slidably in the axial direction in the pump accommodating chamber 16 such that the central portion of the lifter end wall 36a contacts the side surface of the cam 18. As described later, the space defined by the lifter 36, the housing member 12, and the cylinder member 26 functions as a pump chamber for supplying fuel to the high-pressure pump chamber 30. Therefore, this space is hereinafter referred to as a feed pump chamber 38. As described above, the plunger 28 is urged toward the cam 18 by the spring 34. For this reason, the outer surface of the lifter end wall 36a is
8 presses against the side surface of the cam 18.

An inlet orifice 40 communicating between the cam accommodating chamber 14 and the feed pump chamber 38 is provided at a position outside the contact surface of the lifter end wall 36a with the cam 18. An annular leaf spring 42 is disposed on the inner surface of the lifter end wall 36a. Leaf spring 4
A holding spring 44 is disposed between the retainer 32 and the retainer 32. The leaf spring 42 is normally
The inlet orifice 40 is held by a holding spring 44 so as to close it. When the hydraulic pressure on the cam housing chamber 14 side becomes higher than the hydraulic pressure on the feed pump chamber 38 side, the leaf spring 40 bends away from the lifter end wall 36a to conduct the orifice 38.
That is, the leaf spring 42 functions as a check valve that allows only the fluid flow from the cam housing chamber 14 toward the feed pump chamber 38. In this embodiment, the leaf springs 40 are held by the holding springs 42. However, the present invention is not limited to this, and the leaf springs 40 may be held by caulking or the like.

The structure of the first pump mechanism 22 has been described above. As described above, the second pump mechanism 24 also has a substantially symmetric structure with the first pump mechanism 22. For this reason,
About the 2nd pump mechanism 24, the same code | symbol is attached | subjected to the same component as the 1st pump mechanism 22, and the description is abbreviate | omitted. As shown in FIG. 1, the housing member 12 is provided with an inlet port 46 corresponding to each of the first pump mechanism 22 and the second pump mechanism 24. Inlet port 46
Is connected to the fuel tank 10 via a fuel pipe 48. The housing member 12 is provided with a fuel passage 50 connecting the inlet port 46 and the cam accommodating chamber 14.

The housing member 12 is provided with a feed outlet check valve 52 corresponding to each of the first pump mechanism 22 and the second pump mechanism 24, and the first pump mechanism 22 and the second pump mechanism A regulator 54, a suction metering valve 56, and an outlet port 58 common to the mechanism 24 are provided. The common rail 11 is connected to the outlet port 58 via a fuel pipe 59. Also,
The cylinder member 26 is provided with a high pressure outlet check valve 60 corresponding to each of the first pump mechanism 22 and the second pump mechanism 24.

Housing member 12 and cylinder member 26
The fuel passage 62 connects the pump housing chamber 16 and the feed outlet check valve 52, the fuel passage 64 connects the feed outlet check valve 52 and the suction metering valve 56, and the suction metering valve 56
Passage 6 that connects the seal plug 27 to the passage 27b
6. A fuel passage 68 connecting the high-pressure pump chamber 30 and the high-pressure outlet check valve 60 and a fuel passage 70 connecting the high-pressure outlet check valve 60 and the outlet port 58 are provided.

The fuel passage 62 is disposed so as to open to a region including the enlarged diameter portion 16a of the pump accommodating chamber 16.
Therefore, even when the lifter 36 is most displaced toward the cylinder member 26 (that is, the state shown for the second pump mechanism 24 in FIG. 1), the feed pump chamber 38 and the fuel passage 6
2 is maintained. Feed outlet check valve 52
Allows only the flow of fluid from the fuel passage 62 side to the fuel passage 64 side, that is, from the feed pump chamber 38 side to the suction metering valve 56 side. The high-pressure outlet check valve allows only the flow of the fluid from the fuel passage 68 side to the fuel passage 70 side, that is, from the high-pressure pump chamber 30 side to the outlet port 58 side.

The fuel passages described above are arranged inside the housing member 12 and the cylinder member 26 so as to have different heights in a direction perpendicular to the plane of FIG. 1 so as not to cross each other. I have. The regulator 54 described above communicates with a fuel passage 64 corresponding to the second pump mechanism 24 side. When the fuel pressure in the fuel passage 64 exceeds a predetermined regulator pressure, the regulator 54 returns a part of the fuel from the fuel passage 64 to the fuel tank 10 via the return pipe 72 to thereby control the fuel passage 64.
, Ie, the fuel pressure supplied to the inlet side of the suction metering valve 56, is kept constant. Also, the suction metering valve 5
Reference numeral 6 denotes, for example, an electromagnetic flow control valve whose opening is changed in accordance with a control signal supplied from a control device (not shown).

According to the above configuration, when the eccentric shaft 20 is rotated by the drive motor, the cam 18 is rotated by the rotation center S.
Rock around. As described above, the lifter 36 is pressed against the side surface of the cam 18 by the plunger 28. Therefore, when the cam 18 swings, the cam 18 and the lifter end wall 36 are rotated.
The plunger 28 and the lifter 36 reciprocate in the axial direction as a unit while a relatively slides vertically in FIG. As shown in FIG. 1, when the cam 18 is located at the rightmost position in the figure with respect to the rotation center S, the first pump mechanism 22
Plunger 28 and lifter 36 are closest to rotation center S (hereinafter, this position is referred to as bottom dead center of plunger 28 or lifter 36), while plunger 28 and lifter 36 of second pump mechanism 24 rotate. Most distant from the center S (hereinafter, this position is referred to as the plunger 28 or the lifter 3
6 top dead center).

When the cam 18 swings from the state shown in FIG. 1, the plunger 28 of the first pump mechanism 22 and the lifter 3
6 is displaced from the bottom dead center side to the top dead center side, and the plunger 28 and the lifter 36 of the second pump mechanism are displaced from the top dead center side to the bottom dead center side. In this case, as the volume of the feed pump chamber 38 of the second pump mechanism 24 increases, the pressure inside the feed pump chamber 38 decreases. Therefore, fuel in the cam chamber 14 is sucked into the feed pump chamber 38 via the inlet orifice 40, and fuel in the fuel tank 10 is supplied from the inlet port 46 via the fuel passage 50 to the cam chamber 50. It flows into 14. At the same time, the high-pressure pump chamber 30 and the feed pump chamber 38 of the first pump mechanism 22
As the volume of both of them decreases, the hydraulic pressure inside them increases. Therefore, fuel stored in the high-pressure pump chamber 30 of the first pump mechanism 22 is discharged from the outlet port 58 via the fuel passage 68, the high-pressure outlet check valve 60, and the fuel passage 70, and The fuel accommodated in the feed pump chamber 38 of the first pump mechanism 22 is
2. Via the feed outlet check valve 52, the fuel passage 64, the suction metering valve 56, the fuel passage 66, the passages 27b and 27a, and the high pressure inlet check valve 31 to the high pressure pump chamber 30 of the second pump mechanism 24. Supplied.

The plunger 2 of the first pump mechanism 22
8 and the lifter 36 are displaced from the top dead center side to the bottom dead center side, and the plunger 28 and the lifter 3 of the second pump mechanism 24 are displaced.
6 is displaced from the bottom dead center side to the top dead center side, the volumes of the high-pressure pump chamber 30 and the feed pump chamber 38 of the first pump mechanism 22 both increase, while the second pump mechanism 2
The volume of the high-pressure pump chamber 30 and the volume of the feed pump chamber 38 both decrease. Therefore, contrary to the above case, the second
The fuel contained in the high pressure pump chamber 30 of the pump mechanism 24 is discharged from the outlet port 58, and the fuel contained in the feed pump chamber 38 of the second pump mechanism 24 is discharged from the high pressure pump chamber of the first pump mechanism 24. 30.

As described above, in this embodiment, fuel is supplied from one feed pump chamber 38 of the first pump mechanism 22 or the second pump mechanism 24 to the other high-pressure pump chamber 30. That is, one feed pump chamber 38 of the first pump mechanism 22 or the second pump mechanism 24 functions as a feed pump for the other pump mechanism,
The pumping of the fuel by the pump mechanisms 22 and 24 can be performed with high pumping capacity. Hereinafter, the above-described function of introducing fuel into the high-pressure pump chamber 30 is referred to as a feed function. The stroke in which the plunger 28 and the lifter 32 are displaced from the bottom dead center to the top dead center is referred to as a discharge stroke, and the stroke in which the plunger 28 and the lifter 32 are displaced from the top dead center to the bottom dead center is referred to as a suction stroke.

In this embodiment, since the lifter 36 is interposed between the plunger 28 and the cam 18, when the eccentric shaft 20 rotates, the cam 18 and the lifter end wall 3
6a slides. The area of the contact surface of the lifter end wall 36a with the cam 18 is set to be larger than the area of the end surface of the plunger 28. For this reason, the plunger 28
The contact pressure with the cam 18 is increased by increasing the contact area with the cam 18 as compared with the case where the cam 18 and the cam 18 slide directly, so that the cam 18 is less likely to be worn.

Further, since the lifter 36 is interposed between the plunger 28 and the cam 18, the reaction force in the direction perpendicular to the shaft caused by the sliding with the cam 18 is reduced by the lifter 32 and the pump housing 16. In the sliding surface with the inner peripheral surface of Accordingly, since the reaction force is not directly transmitted to the plunger 28, the plunger 28 and the cylinder member 26
A problem such as uneven wear and seizure is prevented from occurring on the sliding surface with the cylinder 26c.

In the present embodiment, the feed pump chamber 38 supplies fuel to the high-pressure pump chamber 30 during the suction stroke of the other pump mechanism (ie, during the process of reducing the pressure in the high-pressure pump chamber 30). Therefore, a high discharge pressure from the feed pump chamber 38 is not required. For this reason, it is not necessary to impart high liquid tightness to the feed pump chamber 38, and a relatively large clearance can be provided between the lifter 36 and the inner peripheral surface of the pump housing chamber 16. Therefore, as described above, even if a reaction force in the direction perpendicular to the axis acts on the sliding surface between the lifter 36 and the pump housing chamber 16, problems such as uneven wear and seizure hardly occur on this sliding surface. ing. Further, since the surface area of the lifter 36 is larger than the surface area of the plunger 28, the lifter 36
The pressure acting between the pump and the inner peripheral surface of the pump housing chamber 16 is suppressed to a small value, and in this sense, uneven wear of the sliding surface is less likely to occur.

As described above, the lifter 36 is a member having an important role in maintaining the function of the pump, and is required regardless of the presence or absence of the feed function. In the present embodiment, by defining the feed pump chamber 38 by the lifter 36, it is possible to realize a feed function while minimizing an increase in the number of components. That is, according to the present embodiment, the feed function is realized only by providing the leaf spring 42 and the feed outlet check valve 52 with respect to the configuration having no built-in feed function.

In this embodiment, the space in which the feed pump chamber 38 is disposed is a space to be ensured for the plunger 28 to reciprocate, and is required regardless of the presence or absence of the feed function. It is. In this sense, in the present embodiment, an increase in the size of the fluid pump for realizing the feed function is also prevented.

As described above, in this embodiment, the feed function can be realized only by forming the feed pump chamber 38 inside the lifter 36 and providing the required check valve. Therefore, according to the fluid pump of the present embodiment, compared to a case where a feed pump is separately provided,
It is possible to reduce the size of the pump and the number of parts.

As described above, the opening of the suction metering valve 56 is changed according to the control signal supplied from the control device. The fuel pressure on the inlet side of the suction metering valve 56 is
It is kept constant by the regulator 54. Therefore, in the suction stroke, an amount of fuel corresponding to the opening degree of the suction metering valve 56 is supplied to the high-pressure pump chamber 30, and in the subsequent discharge stroke,
The fuel is discharged from the outlet port 58. Then, the fuel pressure of the common rail 11 changes according to the amount of fuel discharged from the outlet port 58. Therefore, the control device adjusts the opening of the suction metering valve 56 based on the fuel pressure of the common rail 11, so that the fuel pressure of the common rail 11 can be controlled to a required target value.

As described above, in the fluid pump of this embodiment, the amount of fuel supplied to the common rail 11 is controlled by adjusting the amount of fuel supplied to the high-pressure pump chamber 30 by the suction metering valve 56. It has a configuration. However, the present invention is not limited to this, and the amount of fuel pumped on the discharge side of the high-pressure pump chamber 30 may be adjusted. That is, instead of providing the suction metering valve 56, a relief passage communicating with the fuel tank 10 is connected to a fuel passage 70 connecting the high pressure outlet check valve 60 and the outlet port 58, and the open / close state of this relief passage is changed. It is also possible to adjust the pumping amount by switching and returning the fuel discharged from the outlet port 58 to the fuel tank as appropriate,
Alternatively, a regulator may be provided in the fuel passage 70 and the discharge pressure of the outlet port 58 may be controlled to adjust the pumping amount.

By the way, when the fluid pump of the present embodiment exhibits the maximum pumping capacity, that is, the opening of the suction metering valve 56 is set to the maximum and the amount equal to the maximum volume of the high-pressure pump chamber 30 (hereinafter referred to as the maximum). In order to secure the feed function even when the fuel of the high pressure pumping amount is fed by pressure, the amount of fuel supplied from the feed pump chamber 38 to the high pressure pumping chamber 30 (hereinafter referred to as feed fuel amount) is maximum. It is necessary to secure a value larger than the high pressure pumping amount. Plunger 28
And lifter 36 have the same stroke amount.
Most of the volume of the feed pump chamber 38 is the lifter end wall 36.
a of the housing member 26 and the end face of the cylinder portion 26b of the housing member 26, the feed pump chamber 38
The ratio of the feed fuel amount to the maximum high-pressure pumping amount in a state where the fuel is full is substantially equal to (the sectional area of the feed pump chamber 38 / the sectional area of the high-pressure pump chamber 30) (hereinafter, referred to as a ratio R). . Therefore, by setting the ratio R to be larger than 1, the above requirement regarding the feed fuel amount can be satisfied.

On the other hand, when the ratio R is larger than 1, it means that the amount of fuel supplied from the feed pump chamber 38 is excessive with respect to the amount of fuel to be supplied to the high-pressure pump chamber 30. In this case, the pressure on the outlet side of the feed outlet check valve 52, that is, the pressure in the fuel passage 64 rises and exceeds the regulator pressure of the regulator 54, and excess fuel is returned from the regulator 54 to the fuel tank 10. . Therefore, if the ratio R is set too high, a large amount of fuel is wastefully pumped from the feed pump chamber 38, and the energy efficiency of the pump is reduced. From such a viewpoint, it is desirable that the ratio R is set to be small within a range exceeding 1.

However, as described above, the lifter 36 has a function of preventing the effect of the sliding resistance on the plunger 28 by receiving the sliding resistance from the cam 18. Since the dimensions of the lifter 36 need to be determined based on such a function, it is not always easy to set the ratio R freely. For this reason, the ratio R may have to be set to a value considerably larger than 1.

On the other hand, in this embodiment, the fuel is supplied from the cam accommodating chamber 14 to the feed pump chamber 38 via the inlet orifice 40. In this case, the amount of fuel supplied to the feed pump chamber 38 is limited according to the flow path resistance of the inlet orifice 40. Therefore, according to the present embodiment, even when the ratio R is considerably larger than 1, the inner diameter of the inlet orifice 40 is set to an appropriate value so that the feed fuel amount does not become excessive with respect to the maximum high-pressure pumping amount. By setting to, the amount of fuel wastefully pumped from the feed pump chamber 38 can be suppressed, thereby improving the energy efficiency of the fluid pump.

In the above embodiment, the high pressure pump chamber 30 is provided in the first pump chamber described in the claims, and the feed pump chamber 38 is provided in the second pump chamber described in the claims. 14, the inlet orifice 40, and
The first fluid conveyance mechanism described in the claim where the leaf spring 42 is a claim is a fuel passage 62, a feed outlet check valve 52, the fuel passages 64 and 66, the passages 27 b and 27 a, and the high pressure inlet check valve 31. , Respectively.

Next, a second embodiment of the present invention will be described. FIG. 2 is a configuration diagram illustrating a main part of the fluid pump according to the present embodiment. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The fluid pump of this embodiment includes a lifter 136 instead of the lifter 36 of the first embodiment. The lifter 136 is a cylindrical member having one end closed like the lifter 36. The lifter 136 has a suction hole 140 on a side surface thereof. When the lifter 136 is located at the top dead center as shown in FIG. 2, the suction hole 140 is closed by the inner wall of the pump housing chamber 16, and the lifter 136 extends a predetermined distance d from the top dead center to the bottom dead center side. In the displaced state, the cam housing 14 and the feed pump chamber 38 are arranged so as to communicate with each other by being exposed to the cam housing 14.

The operation of the fluid pump according to the present embodiment will be described below with reference to FIGS. As described above, the suction hole 140 of the lifter 136 is closed by the inner wall of the pump housing chamber 16 until the amount of displacement from the top dead center to the bottom dead center of the lifter 136 reaches the predetermined distance d. For this reason, even if the volume of the feed pump chamber 38 increases due to the displacement of the lifter 136 toward the bottom dead center,
The suction of fuel from the cam housing chamber 14 into the feed pump chamber 38 is prevented.

When the amount of displacement of the lifter 136 from the top dead center reaches a predetermined distance d, as shown in FIG. 3, the suction hole 140 is exposed to the cam accommodating chamber 14 (hereinafter, this position is referred to as the lifter 136). Is called the critical position of inhalation). For this reason,
After the lifter 136 has passed the critical suction position, fuel is sucked from the cam housing chamber 14 through the suction hole 140 into the feed pump chamber 38 until the bottom dead center is reached as shown in FIG.

When the lifter 136 passes the bottom dead center, it is displaced toward the top dead center. In this case, until the lifter 136 reaches the critical suction position, the suction hole 140 is exposed to the cam storage chamber 14. For this reason, when the volume of the feed pump chamber 38 decreases as the lifter 136 is displaced toward the top dead center, the fuel in the feed pump chamber 38 flows out from the suction hole 140 to the cam accommodating chamber 14 and the feed outlet No fuel is discharged from the check valve 52.

When the lifter 136 exceeds the critical suction position,
Since the suction hole 140 is closed by the inner wall of the pump chamber 16, the fuel in the feed pump chamber 38 cannot flow out to the cam chamber 14 thereafter. Therefore, as the volume of the feed pump chamber 38 decreases, the feed pump chamber 3
8, the fuel pressure in the feed pump chamber 38 increases.
Through the feed outlet check valve 52 to the high pressure pump chamber 30.

As described above, in the fuel pump of this embodiment, when the lifter 136 reaches the critical suction position from the bottom dead center, the fuel present in the feed pump chamber 38 is pumped from the feed outlet check valve 52. Will be. Therefore,
By adjusting the critical suction position according to the position of the suction hole 140 of the lifter 136, the amount of fuel pumped from the feed outlet check valve 52 is set to an appropriate value according to the amount of fuel to be supplied to the high-pressure pump chamber 30. can do.

Further, in the fuel pump of the present embodiment, the fuel is discharged from the feed outlet check valve 52 in a state where the suction hole 140 is closed.
It is not necessary to provide a check valve (leaf spring 42 in the first embodiment) on the inlet side in order to prevent the backflow of fuel from the fuel into the cam chamber 14. Therefore, according to the fuel pump of the present embodiment, it is possible to further reduce the number of components.

In the second embodiment, the suction hole 140 and the inner wall of the pump chamber 16 correspond to the flow path blocking mechanism described in the claims. Note that the first and second
In the embodiment, two sets of the high-pressure pump chamber 30 and the feed pump chamber 38 which expand and contract in the same direction are provided, and the expansion and contraction of each pump chamber of one set is enlarged and reduced of each pump chamber of the other set. In the configuration opposite to the above, one set of the feed pump chambers 38 functions as a feed pump for the other set of the high-pressure pump chambers 30. However, the present invention is not limited to this.
It is also conceivable to provide a pair of high-pressure pump chamber and feed pump chamber on opposite sides of the cam so that the two pump chambers are oppositely enlarged and reduced. Or,
It is also conceivable to provide a high-pressure pump chamber and a feed pump chamber on both sides of a plunger in the same cylinder so that the expansion and contraction of both pump chambers are reversed.

[0048]

As described above, according to the first and second aspects of the present invention, the feed function can be realized without separately providing a feed pump, thereby preventing an increase in the size of the pump and an increase in the number of components. can do. According to the third aspect of the present invention, it is not necessary to provide a check valve in the flow path for supplying the fluid to the second pump chamber, so that the number of components can be further reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fluid pump according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of a fuel pump according to a second embodiment of the present invention.

FIG. 3 is a view showing a state where the fuel pump shown in FIG. 2 is displaced toward a bottom dead center of a lifter.

FIG. 4 is a diagram showing a state in which a lifter of the fuel pump shown in FIG. 2 is at a bottom dead center.

5 is a diagram showing a state where the fuel pump shown in FIG. 2 is displaced toward a lifter top dead center.

[Explanation of symbols]

 22 first pump mechanism 24 second pump mechanism 28 plunger 30 high-pressure pump chamber 31 high-pressure inlet check valve 36 lifter 38 feed pump chamber 40 inlet orifice 42 leaf spring 52 feed outlet check valve 27a, 27b passage 50, 62, 64, 66, 68, 70 Fuel passage

Continued on the front page (72) Inventor Motoichi Murakami 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. F-term (reference) 3H070 AA02 BB02 BB16 BB17 BB21 CC34 CC37 DD01 DD11 DD26 DD35 DD66 DD91

Claims (3)

[Claims] 1. A fluid pump comprising: a reciprocating plunger; and a first pump chamber that expands and contracts in accordance with the reciprocating motion of the plunger, wherein the first pump chamber responds to a reciprocating motion of the plunger. A second pump chamber that expands when the first pump chamber shrinks when the first pump chamber shrinks, and a fluid supplied from an external fluid source when the second pump chamber expands. A first fluid transfer mechanism that supplies a fluid in the second pump chamber to the first pump chamber when the second pump chamber is reduced. Characteristic fluid pump. 2. A plurality of sets each including a reciprocating plunger, a first pump chamber that expands and contracts in accordance with the reciprocation of the plunger, and a second pump chamber formed separately from the first pump chamber. A fluid pump comprising: a first set of pump chambers of another set shrinks when a first set of pump chambers of the set expands due to reciprocating motion of one set of plungers, and a first set of pump chambers of the set shrinks; The second pump chamber of the other set is configured to expand, and a first fluid carrier that supplies a fluid supplied from an external fluid source to the second pump chamber when each second pump chamber expands. A fluid pump comprising: a mechanism; and a second fluid transfer mechanism that supplies a fluid in the second pump chamber to a predetermined first pump chamber when each of the second pump chambers is reduced. 3. The fluid pump according to claim 1, wherein the first fluid transport mechanism includes: a fluid passage communicating the second pump chamber with the fluid source; and a fluid passage according to a position of the plunger. A fluid pump, comprising: a flow path blocking mechanism that switches between conduction and blocking of a passage.