JP5404839B2 - Fuel supply device - Google Patents

Description

  The present invention relates to a fuel supply device that supplies fuel in a fuel tank to a fuel injection device by reciprocation of a piston.

  Due to environmental problems such as global warming, regulations on fuel consumption and exhaust gas for gasoline engines are becoming stricter. In recent years, regulations on small displacement engines such as small two-wheeled vehicles are also being enforced. Against this background, fuel supply systems for engines of four-wheeled vehicles and two-wheeled vehicles are replaced by conventional mechanical systems using carburetors. In order to reduce the fuel consumption of the engine and clean the exhaust gas, electronic control, that is, FI (Fuel Injection) is required.

An in-tank fuel supply device installed in a fuel tank is employed in automobiles, medium and large-sized motorcycles, and the like. However, in the case of an engine with a small displacement, since the capacity of the fuel tank is small, it is necessary to review the layout of the fuel tank significantly in order to mount the in-tank fuel supply device.
Therefore, a small and lightweight in-line fuel supply device that can be mounted on a pipe between a fuel tank and a fuel injection device is employed for the FI of a small displacement engine.

And since the in-line type fuel supply apparatus needs to self-prime the fuel in the fuel tank, a piston type pump excellent in self-priming performance has been proposed.
As the fuel supply device, the amount of steam generated in the pressure increasing chamber is suppressed by defining the shape of the suction passage, and the discharge of steam generated in the pressure increasing chamber is ensured by defining the volume ratio in the pressure increasing chamber. Those are known (for example, see Patent Document 1).

Japanese Patent No. 4512152

  However, in this case, when the fuel pump is used in a higher temperature environment than the steam discharge, the volume of the suction passage between the cylinder block suction hole and the cylinder bore is reduced in order to increase the fuel compression ratio. Although it is necessary to reduce the height as much as possible, there is a problem that if the height of the suction passage is lowered, the pressure loss of the fuel increases and the volumetric efficiency decreases.

  An object of the present invention is to solve such problems, and to reduce the pressure loss of fuel in the intake passage while ensuring a predetermined compression ratio, and to ensure high volumetric efficiency even in a harsh usage environment. It is an object of the present invention to obtain a fuel supply device that can perform the above-described operation.

A fuel supply device according to the present invention includes a suction port through which fuel is sucked, a cylinder block having a cylinder bore, a piston that reciprocates in the cylinder bore,
A valve plate provided in surface contact with the end surface of the cylinder block and having a suction passage communicating with the suction hole and a discharge hole for discharging the fuel, and sandwiched between the valve plate and the cylinder block A plate-like suction valve that opens and closes the suction hole, a casing provided in surface contact with the valve plate and having a discharge groove communicating with the discharge hole, and between the casing and the valve plate And a plate-like discharge valve that opens and closes the discharge hole, and when the piston moves from the top dead center to the bottom dead center in the cylinder bore, the suction valve opens to When the fuel flows into the cylinder bore through the suction hole and the suction passage, and the piston moves in the cylinder bore from the bottom dead center to the top dead center, the suction Valve is closed, said discharge valve is opened the fuel flows from the discharge hole to the discharge groove, a fuel supply device is supplied to the fuel injection device,
The end face of the cylinder block is formed with a notch that is inclined from the portion between the suction hole and the opening of the cylinder bore and connected to the cylinder bore.

The fuel supply apparatus according to the present invention is provided in surface contact with a cylinder block having a suction hole for sucking fuel and a cylinder bore, a piston reciprocating in the cylinder bore, and an end face of the cylinder block, A valve plate having a suction passage communicating with the suction hole and a discharge hole for discharging the fuel, and a plate-like suction valve provided between the valve plate and the cylinder block to open and close the suction hole A casing having a discharge groove provided in surface contact with the valve plate and communicating with the discharge hole, and a plate-like shape provided between the casing and the valve plate to open and close the discharge hole And when the piston moves from the top dead center to the bottom dead center in the cylinder bore, the suction valve is opened. When the fuel flows into the cylinder bore through the suction hole and the suction passage, and when the piston moves from the bottom dead center to the top dead center in the cylinder bore, the suction valve closes and the discharge A fuel supply device in which a valve is opened and the fuel flows into the discharge groove from a discharge hole,
An inclined notch is formed at the edge of the discharge hole of the valve plate, starting from a portion facing the portion between the suction hole and the opening of the cylinder bore.

  According to the fuel supply device of the present invention, the end face of the cylinder block is formed with a notch that is inclined from the portion between the suction hole and the opening of the cylinder bore and connected to the cylinder bore. While ensuring a predetermined compression ratio, the pressure loss of the fuel in the intake passage can be reduced, and high volumetric efficiency can be ensured even in a more severe use environment.

  Further, according to the fuel supply device of the present invention, the discharge hole is inclined at the edge of the discharge hole of the valve plate, starting from the part facing the part between the suction hole and the opening of the cylinder bore. Since the notch portion connected to is formed, the pressure loss of the fuel in the intake passage can be reduced while ensuring a predetermined compression ratio, and high volumetric efficiency can be ensured even in a harsh usage environment.

It is a figure which shows the fuel supply system which has a fuel supply apparatus of Embodiment 1 of this invention. It is sectional drawing which shows the fuel supply apparatus of FIG. FIG. 3 is an enlarged view of a main part of FIG. 2. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3. It is a figure which shows the flow of the fluid when a suction hole opens in the fuel supply apparatus of FIG. It is a figure which shows the relationship between a compression ratio when a vapor | steam is satisfy | filled in the fuel pump, and the maximum ultimate pressure. It is a relationship figure which shows the relationship between the distance from the starting point of a notch part, and a suction hole, and volumetric efficiency. It is a relationship figure which shows the relationship between the height and width | variety of a suction passage. It is a principal part enlarged view of the fuel supply apparatus of Embodiment 2 of this invention. FIG. 10 is a front view showing the cylinder bore of FIG. 9. It is sectional drawing which shows the fuel supply apparatus of Embodiment 3 of this invention. It is a principal part enlarged view of FIG. It is arrow sectional drawing along XIII-XIII of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or equivalent members and parts will be described with the same reference numerals.

Embodiment 1 FIG.
1 is a view showing a fuel supply system having a fuel supply device 3 according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view showing the fuel supply device 3 of FIG. 1, and FIG. 3 is an enlarged view of a main part of FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG.
This fuel supply system includes a fuel tank 1, a fuel supply device 3 connected to the fuel tank 1 via a low pressure pipe 2 outside the fuel tank 1, and a fuel pressure adjusting device 7 built in, and a high pressure pipe 4. A fuel injection device 5 that is connected to the fuel supply device 3 and injects fuel supplied from the fuel supply device 3, and a communication pipe 6 that connects the fuel pressure adjusting device 7 and the fuel tank 1 are provided.

  When the difference between the fuel pressure in the high-pressure pipe 4 and the fuel pressure in the fuel tank 1 becomes larger than a specified value, the fuel pressure adjusting device 7 communicates between the high-pressure pipe 4 and the fuel tank 1 and the fuel in the high-pressure pipe 4. Is returned to the fuel tank 1 through the connecting pipe 6. That is, the fuel pressure supplied to the fuel injection device 5 is adjusted to a predetermined value by the fuel pressure adjustment device 7.

The fuel supply device 3 includes a motor 10 and a fuel pump 11 that is a positive displacement axial piston pump connected to the motor 10.
The fuel pump 11 has a suction port 12 connected to the low-pressure pipe 2 and a discharge port 13 connected to the high-pressure pipe 4 and is connected to the motor 10 and a shaft extending on the axis A of the housing 14. The swash plate 16 is fixed to 15 and rotates in conjunction with the rotation of the shaft 15, and the casing 17 is fitted in the housing 14 and has a discharge groove 33.

The fuel pump 11 includes a piston 22, a cylinder block 24 having a cylinder bore 21 and a suction hole 23 provided in the housing 14 and reciprocally sliding along the axial direction, an end surface of the cylinder block 24, and the piston 22. A spring 32 that is provided between the cylinder block 24 and the casing 17 and has a discharge hole 26, and a valve plate. 25 and a cylinder block 24 and is provided between the valve plate 25 and the casing 17, and is provided between the valve plate 25 and the casing 17 to close the discharge hole 26. And a discharge valve 28 formed of a leaf spring.
The suction valve 27 includes a valve body 40 that covers the opening of the suction hole 23, and a rectangular base 41 that is continuously provided on the valve body 40.
On the side of the cylinder block 24 of the valve plate 25, a rectangular intake passage 29 is formed that connects between the suction hole 23 of the cylinder block 24 and the opening of the cylinder bore 21.
Here, the space partitioned by the suction valve 27, the discharge valve 28 and the piston 22 is the pressure increasing chamber B.

  A notch 34 connected to the cylinder bore 21 is formed on the end face of the cylinder block 24. The notch 34 has an arc shape starting from a portion between the suction hole 23 and the opening of the cylinder bore 21, and the projected shape is a crescent shape.

The fuel pressure adjusting device 7 is provided through the casing 17 and the cylinder block 24, and the check valve 18 is attached to the casing 17 so as to face the discharge port 13.
The sealing member 30 seals between the fuel pump 11 and the motor 10 and seals between the outer peripheral wall surface of the casing 17 and the inner peripheral wall surface of the housing 14. The bearing 31 supports the shaft 15 rotatably.

Next, the operation of the fuel supply device 3 configured as described above will be described.
As an initial state, it is assumed that fuel is filled in the fuel reservoir chamber C (the space on the suction port 12 side with respect to the suction valve 27 in the housing 14).
When the swash plate 16 rotates in conjunction with the rotation of the shaft 15 by the motor 10, the piston 22 urged against the swash plate 16 by the spring 32 causes the top dead center and lower Move back and forth between dead centers.

When the piston 22 moves from the top dead center to the bottom dead center, the volume in the pressure increasing chamber B increases and the pressure in the pressure increasing chamber B is reduced. When the piston 22 moves toward the top dead center, the volume in the pressure increasing chamber B decreases. The pressure in the pressure increasing chamber B is increased.
At this time, the pressure in the pressure increasing chamber B becomes larger or smaller than the pressure in the fuel reservoir chamber C due to the reciprocating movement of the piston 22.

When the pressure in the pressure increasing chamber B is lower than the pressure in the fuel reservoir chamber C, the valve body 40 of the intake valve 27 is displaced toward the valve plate 25 as shown in FIG. The pressure increasing chamber B is communicated.
That is, when the piston 22 is displaced from the top dead center toward the bottom dead center, the fuel in the pressure increasing chamber B is depressurized, and the suction valve 27 is displaced so as to open the opening of the suction hole 23. The fuel in the fuel retaining chamber C flows into the cylinder bore 21 of the cylinder block 24 through the suction passage 29.
At this time, in the discharge valve 28, since the pressure in the pressure increasing chamber B is lower than the pressure on the discharge groove 33 side of the casing 17, the discharge valve 28 is displaced to the valve plate 25 side, and the discharge hole 26 is closed. ing.

Further, when the piston 22 is displaced from the bottom dead center to the top dead center and the pressure in the pressure increasing chamber B is increased and becomes higher than the pressure in the fuel reservoir chamber C, the valve body 40 of the intake valve 27 is changed. Displaced to the cylinder block 24 side, the suction valve 27 closes the suction hole 23 and blocks the communication between the fuel retaining chamber C and the pressure increasing chamber B.
Further, as the piston 22 moves to the top dead center side, the inside of the pressure increasing chamber B is pressurized, and when the pressure becomes higher than the pressure on the discharge groove 33 side, the discharge valve 28 is displaced to the casing 17 side, The discharge hole 26 is opened.
The high-pressure fuel in the pressure increasing chamber B is supplied to the fuel injection device 5 through the discharge hole 26, the discharge groove 33, the check valve 18, the discharge port 13, and the high-pressure pipe 4.

  By the way, when the inside of the pressure increasing chamber B is filled with fuel, the state equation of the pressure in the pressure increasing chamber B is expressed by the following equation (1).

P = K · ΔV / V (1)
P: Fuel pressure K: Fuel bulk modulus (1GPa for gasoline)
ΔV: Volume change amount of the pressure increasing chamber B (pushing volume, moving volume of the piston 22)
V: Maximum volume of the pressure increasing chamber B (volume when the piston 22 is at bottom dead center)

  Moreover, since the state equation of the pressure in the pressure increasing chamber B when the pressure increasing chamber B is filled with steam can be considered that the volume of the pressure increasing chamber B is changing in the adiabatic state, the equation (2) It can be expressed as

p · v ^k = p ′ · (v−Δv) ^k (2)
p: pressure in the pressure increasing chamber B before the volume change v: volume of the pressure increasing chamber B before the volume change (volume when the piston 22 is at the bottom dead center)
p ′: Pressure in the pressure increasing chamber B after the volume change (volume when the piston 22 is at the top dead center)
v−Δv: Volume of the pressure increasing chamber B after the volume change Δv: Volume change amount of the pressure increasing chamber B (displacement volume, movement volume of the piston 22)
k: Gas constant (in the case of air, 1.402)

  When gasoline, which is a fuel, falls below the pressure indicated by the saturated vapor pressure curve, steam is generated. When steam is generated in the fuel pump 11, the volumetric efficiency (amount of fuel actually discharged with respect to the moving volume of the piston 22) is rapidly deteriorated as compared with the liquid-tight case.

FIG. 6 shows the relationship between the compression ratio and the maximum ultimate pressure when the fuel pump 11 is filled with steam.
Here, the compression ratio is (v + Δv) / v, and the maximum ultimate pressure is the maximum ultimate pressure in the pressure increasing chamber B.
As can be seen from FIG. 6, the higher the compression ratio of the pressure increasing chamber B, the higher the pressure of the steam in the pressure increasing chamber B, and the more the steam is compressed.
That is, the higher the compression ratio, the more the vapor is compressed, and the proportion of the liquid fuel occupying the pressure-increasing chamber B increases accordingly, so that the liquid fuel discharge capacity increases.
In order to increase the compression ratio and increase the liquid fuel discharge capacity, when the volume change amount Δv of the pressure increasing chamber B is constant, the value of the volume v of the pressure increasing chamber B before the volume change is decreased. Therefore, the volume of the suction passage 29 is set to be small.

On the other hand, the piston 22 moves from the top dead center to the bottom dead center, and there is a problem of reduced pressure boiling during the suction stroke in which the pressure in the pressure increasing chamber B is reduced.
When the fuel flows into the suction passage 29 from the suction hole 23, if the effective cross-sectional area of the suction passage 29 is not sufficiently secured with respect to the flow rate, the fuel flow choke and steam is generated.
When the volume in the suction passage 29 is to be reduced in order to increase the compression ratio and improve the steam discharge performance, it is necessary to reduce the height H in order to reduce the flow passage cross-sectional area of the suction passage 29. However, as a result, the pressure loss of the fuel in the suction passage 29 increases, and the volumetric efficiency is reduced.

In the fuel supply device 3 of this embodiment, in view of the above problems, measures are taken to reduce the pressure loss of the fuel in the suction passage 29 while minimizing the volume increase in the pressure increasing chamber B.
That is, a notch 34 connected to the cylinder bore 21 is formed on the end face of the cylinder block 24, and the flow passage cross-sectional area of the suction passage 29 at that portion is enlarged.
The fuel flowing in from the suction hole 23 passes through the suction valve 27 and flows into the suction passage 29 having a small effective cross-sectional area of the flow path, and the fuel pressure loss increases, but the portion where the pressure drop is the largest is the start point D The notch 34 is formed, and the cross-sectional area of the flow path is enlarged. As a result, the flow of fuel is choked and the generation of steam is suppressed.

In this way, by limiting the expansion of the cross-sectional area of the suction passage 29 to a portion where the pressure drop is large, a predetermined compression ratio is ensured while minimizing the volume increase in the pressure increasing chamber B, High volumetric efficiency is ensured even in a more severe use environment.
Further, the inclined cutout portion 34 communicates with the cylinder bore 21, and a rapid change in the flow from the suction passage 29 to the cylinder bore 21 is alleviated, and the separation of the flow is suppressed.

Further, the notch 34 has an arc shape with a starting point D between the suction hole 23 and the opening of the cylinder bore 21 as an apex, and the arc is a semicircle or less arc.
In the case where the arc of the notch 34 is a semicircle or more, the fuel is contracted by the notch 34 flowing from the suction passage 29 to the cylinder bore 21, and this causes a pressure loss of the fuel. In the embodiment, the notch 34 is an arc of a semicircle or less, so such inconvenience does not occur.

By the way, the fuel flowing into the suction passage 29 from the suction hole 23 loses pressure due to the reduction in the cross-sectional area of the flow path, and the flow is choked.
It is most effective to reduce the pressure loss of the fuel by providing the notch 34 at the position where the pressure drop is maximum, but this position depends on the height H of the suction passage 29.
FIG. 7 is a relationship diagram showing the relationship between the distance L from the starting point D of the notch 34 to the suction hole 23 and the volumetric efficiency.
This relationship diagram is a diagram obtained by the inventor of the present application by comparing the first embodiment with that of Patent Document 1.
Here, the distance L is the distance between the start point D and the intersection of the peripheral edge of the suction hole 23 that intersects the straight line on the straight line connecting the start point D and the center point of the suction hole 23.

From FIG. 7, when the distance L exceeds 5 times the height H of the suction passage 29, there is almost no difference in volumetric efficiency between the first embodiment and that of Patent Document 1, but the suction passage 29. It can be seen that up to five times the height of the first embodiment, the volume efficiency of the first embodiment is higher than that of Patent Document 1.
That is, it can be seen that when the notch 34 is formed at a distance L up to five times the height of the suction passage 29, the effect of reducing the fuel pressure loss of the notch 34 is effective.

The main purpose of forming the notch 34 is to reduce the pressure loss of the fuel in the suction passage 29, but the effective sectional area of the suction passage 29 is sufficiently secured, and The effect is reduced if the pressure loss of the fuel is small.
FIG. 8 is a relationship diagram showing the relationship between the (width W / height H) of the suction passage 29 and the volumetric efficiency.
This relationship diagram is a diagram obtained by the inventor of the present application by comparing the first embodiment with that of Patent Document 1.
As can be seen from FIG. 8, when W / H is 7 or more, the volume efficiency of the first embodiment is higher than that of Patent Document 1.
That is, it can be seen that when the W / H is 7 or more, the effect of reducing the pressure loss of the fuel starts to work effectively.

Embodiment 2. FIG.
FIG. 9 is a cross-sectional view of the main part showing the fuel supply device 3 according to Embodiment 2 of the present invention, and FIG. 10 is a front view showing the cylinder bore 21 of the cylinder block 24.
In this embodiment, a notch 34 is formed to be connected to the tapered portion 35 with respect to the tapered portion 35 which is a chamfer formed at the edge of the cylinder bore 21 of the cylinder block 24.
The edge portion 36 where the notch 34 and the tapered portion 35 intersect is located outside the sliding range of the piston 22.
Other configurations are the same as those of the fuel supply device 3 of the first embodiment.

When the cylinder block 24 is cut, burrs and burr are generated at the edge portion 36, and the burr and burr may damage the piston 22 when the piston reciprocates. If it is attempted to completely remove the burrs and burr formed on the edge portion 36, the deburring process increases and the manufacturing cost increases.
However, in this embodiment, since the edge portion 36 is located outside the sliding range of the piston 22, it is possible to avoid the piston 22 from being damaged by burrs and burr formed on the edge portion 36. .

Embodiment 3 FIG.
11 is a cross-sectional view showing a fuel supply device 3 according to Embodiment 3 of the present invention, FIG. 12 is an enlarged view of a main part of FIG. 11, and FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. It is.
In this embodiment, an arcuate cutout 34 is formed at the edge of the discharge hole 26 of the valve plate 25 on the suction passage 29 side.
The starting point D of the notch 34 is a part facing the part between the suction hole 23 and the opening of the cylinder bore 21. The notch 34 inclined from the starting point D is connected to the discharge hole 26. Yes.
Other configurations are the same as those of the fuel supply device 3 of the first and second embodiments.

  Also in this embodiment, although the effective cross-sectional area of the flow channel flows from the suction hole 23 into the suction passage 29 and the fuel pressure loss increases, the point where the pressure drop is the largest is the start point D as in the first embodiment. The notch 34 is formed, the cross-sectional area of the flow path is enlarged, the generation of steam by suppressing the choke of the fuel flow, and the same effect as in the first embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 1 Fuel tank, 2 Low pressure piping, 3 Fuel supply apparatus, 4 High pressure piping, 5 Fuel injection apparatus, 6 Connection piping, 7 Fuel pressure regulator, 10 Motor, 11 Fuel pump, 12 Intake port, 13 Discharge port, 14 Housing, 15 Shaft, 16 Swash plate, 17 Casing, 18 Check valve, 19 Suction hole, 21 Cylinder bore, 22 Piston, 23 Suction hole, 24 Cylinder block, 25 Valve plate, 26 Discharge hole, 27 Suction valve, 28 Discharge valve, 29 Suction Passage, 30 sealing member, 31 bearing, 32 spring, 33 discharge groove, 34 notch, 35 taper, 36 edge, 40 valve body, 41 base, A axis, B pressure increasing chamber, C fuel reservoir chamber, D Starting point.

Claims (6)

A cylinder block having a suction hole for sucking fuel and a cylinder bore;
A piston that reciprocates in the cylinder bore;
A valve plate provided in surface contact with the end face of the cylinder block, having a suction passage communicating with the suction hole, and a discharge hole for discharging the fuel;
A plate-like suction valve that is sandwiched between the valve plate and the cylinder block and opens and closes the suction hole;
A casing provided in surface contact with the valve plate and having a discharge groove communicating with the discharge hole;
A plate-like discharge valve provided between the casing and the valve plate and opening and closing the discharge hole;
When the piston moves from the top dead center to the bottom dead center in the cylinder bore, the intake valve is opened and the fuel flows into the cylinder bore through the intake hole and the intake passage.
Further, when the piston moves from the bottom dead center to the top dead center in the cylinder bore, the suction valve is closed, the discharge valve is opened, and the fuel flows into the discharge groove from the discharge hole. A fuel supply device to be supplied to the fuel injection device,
2. A fuel supply apparatus according to claim 1, wherein a notch portion is formed at an end face of the cylinder block so as to be inclined from a portion between the suction hole and the opening portion of the cylinder bore and connected to the cylinder bore. A cylinder block having a suction hole for sucking fuel and a cylinder bore;
A piston that reciprocates in the cylinder bore;
A valve plate provided in surface contact with the end face of the cylinder block, having a suction passage communicating with the suction hole, and a discharge hole for discharging the fuel;
A plate-like suction valve that is sandwiched between the valve plate and the cylinder block and opens and closes the suction hole;
A casing provided in surface contact with the valve plate and having a discharge groove communicating with the discharge hole;
A plate-like discharge valve provided between the casing and the valve plate and opening and closing the discharge hole;
When the piston moves from the top dead center to the bottom dead center in the cylinder bore, the intake valve is opened and the fuel flows into the cylinder bore through the intake hole and the intake passage.
Further, when the piston moves from the bottom dead center to the top dead center in the cylinder bore, the suction valve is closed, the discharge valve is opened, and the fuel flows from the discharge hole into the discharge groove. A fuel supply device,
A notch connected to the discharge hole at an edge of the opening of the discharge hole of the valve plate and inclined from a portion opposed to a portion between the suction hole and the opening of the cylinder bore A fuel supply device having a portion formed therein. The cylinder bore is formed with a chamfered taper on the peripheral edge,
The fuel supply device according to claim 1, wherein the cutout portion is connected to the tapered portion and has an edge portion.   2. The fuel supply device according to claim 1, wherein the notch has an arc shape of a semicircle or less with the start point as an apex.   In a straight line connecting the start point and the center point of the suction hole, the distance between the start point and the intersection of the peripheral edge of the suction hole intersecting the straight line is not more than 5 times the height of the suction passage. The fuel supply device according to claim 1, wherein the fuel supply device is provided.   6. The fuel supply device according to claim 1, wherein W / H is 7 or more when the width of the suction passage is W and the height is H. 6.

Images