JP3564912B2 - Fuel pump for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel pump for an internal combustion engine including a regenerative pump, and more particularly to a configuration of a fuel introduction unit for solving a problem of a decrease in flow rate due to suction of vapor.
[0002]
[Prior art]
As is well known, a regenerative pump is configured by accommodating an impeller in which a large number of blade pieces and blade grooves are alternately formed on an outer peripheral portion in a casing having an end-shaped annular pump flow path, and configured to rotate the impeller. Thereby, the liquid fluid is sucked into the pump flow path from the suction port of the casing, and the sucked liquid fluid is pressurized while circulating between the blade groove and the pump flow path to finally become a high-pressure liquid fluid and discharged. Discharge from outlet.
[0003]
A regenerative pump having such a pumping function can obtain a considerably high discharge pressure even for a low-viscosity fluid, and thus has been often used as a fuel pump for an internal combustion engine. However, since liquid fuel of an internal combustion engine represented by gasoline has a property of being easily vaporized, the regeneration pump used for the fuel pump for the internal combustion engine tends to cause a problem that the discharge flow rate decreases due to the suction of vapor. .
[0004]
That is, when the impeller rotates, the starting end of the pump flow path becomes a negative pressure, whereby liquid fuel stored in the fuel tank is sucked into the pump flow path from the suction port. The liquid fuel sucked into the pump flow path from the suction port is reduced in pressure due to the negative pressure in the suction port, and partially vaporized, and vapor is mixed into the liquid fuel as bubbles. Become. If vapor is mixed in the pump flow path, the impeller cannot perform a pumping operation that is effective, and the discharge flow rate decreases.
[0005]
Since the ease of vaporization of the liquid fuel increases as the temperature increases, at high temperatures, the liquid fuel stored in the fuel tank boils and evaporates. Bubbles mixed in the liquid fuel are also sucked. Therefore, when the temperature is high, the fuel pump not only increases the amount of vaporization due to the negative pressure in the suction port portion than usual, and also inherently generates bubbles (vapor) in the liquid fuel sucked into the pump passage. , A large amount of vapor is mixed into the pump flow path, and the discharge flow rate is significantly reduced.
[0006]
In order to prevent a decrease in the discharge flow rate due to mixing of vapor, for example, in Japanese Patent Application Laid-Open No. Hei 5-195977, the starting end side (suction port side) of the pump flow path is expanded toward the rotation center side of the impeller to thereby increase the pump flow. The starting end of the flow path is a vapor reservoir having a large internal volume, and a vapor removal hole is formed at the end of the vapor reservoir.
[0007]
With this configuration, the vapor mixed in the liquid fuel sucked into the pump flow path or the vapor generated when the liquid fuel is sucked into the pump flow path from the suction port is temporarily stored in the vapor reservoir. Stored in the department. Then, the vapor stored in the vapor reservoir is sent to the terminal end side of the vapor reservoir little by little as the impeller rotates, and is withdrawn from the vapor removal hole. As a result, the vapor is prevented from flowing into the step-up flow path, which is the pump flow path after the vapor reservoir, so that a decrease in the discharge flow rate can be prevented.
[0008]
[Problems to be solved by the invention]
By the way, the inner surface of the casing forming the vapor reservoir portion is opposed to the side surface of the impeller with a small gap, and the gap between the pump passage and the concave portion formed for inserting the drive shaft into the center of the casing. It has the function of sealing. As shown in JP-A-5-195977, a vapor reservoir having a large internal volume is formed on the inner surface of the casing having such a sealing function by enlarging the starting end of the pump flow path toward the center. If it is formed, it means that the distance between the vapor reservoir (pump flow path) and the central recess becomes short, which undesirably results in a decrease in the sealing performance.
[0009]
On the other hand, as another known configuration example of the vapor reservoir, in consideration of the fact that the casing of the fuel pump is disposed in the fuel tank so that one side surface of the impeller is directed upward, FIG. As shown in the figure, the inner part of the pump flow path 1 located above the impeller 2 is pressurized so that the start end on the suction port 3 side is the deepest and the depth from the deepest part 4a of the start end is constant. In some cases, the upper portion is expanded upward so as to be gradually shallower toward 5, and this expanded portion is used as a vapor reservoir 4.
[0010]
In this configuration, the vapor reservoir 4 having a large internal volume is formed by enlarging the start end portion of the pump flow path 1 in the axial direction of the casing 6, so that the vapor reservoir 4 and the concave portion at the center of the casing 6 are formed. (Not shown) can be maintained well. However, in this configuration, the vapor is stored in the deepest portion 4a of the vapor reservoir 4, but the deepest portion 4a is located at the start end of the vapor reservoir 4 and is far away from the pressurizing flow path 5. The vapor initially stored in the deepest portion 4a is hardly attracted to the rotating impeller 2, and it is difficult to reach the vapor removal hole 7 at the end of the vapor storage portion 4.
[0011]
In other words, if a certain amount of vapor is stored in the vapor storage part 4 and the vapor layer does not approach the impeller 2 to some extent, the vapor is not drawn to the impeller 2. However, when a large amount of vapor is stored in the vapor storage section 4 and the vapor is drawn to the impeller 2, the vapor stored in the vapor storage section 4 flows toward the pressurizing flow path section 5 at a time. Become like However, at this time, since the amount of vapor flowing toward the pressurizing flow path unit 5 side is too large, all of the vapor cannot be extracted from the vapor discharge hole 7, and as a result, most of the vapor flows to the pressurizing flow path unit 5. As a result, the discharge flow rate decreases due to vapor suction.
[0012]
As described above, conventionally, in order to form a vapor reservoir without deteriorating the sealing performance between the inner surface of the casing and the side surface of the impeller, the starting end of the pump flow path is expanded in the axial direction of the casing to form the vapor. In such a structure, a large amount of vapor flows out of the vapor reservoir at one time, so that it is difficult to process a large amount of vapor. There has been a problem that a decrease in the discharge flow rate due to suction cannot be avoided.
[0013]
Recently, in order to increase the output of an internal combustion engine, the fuel pump has been required to have a large discharge flow rate and a stable discharge flow rate. In the regenerative pump, the demand for an increase in the discharge flow rate is achieved by increasing the rotation speed of the impeller.However, as the rotation speed of the impeller increases, the negative pressure in the suction port increases, so that the liquid fuel is further vaporized. And a larger amount of vapor is generated. At a high temperature, the liquid fuel generates a larger amount of vapor. Therefore, it is necessary to improve the vapor discharge performance of the regeneration pump in order to satisfy the demand for a large discharge flow while suppressing the fluctuation of the discharge flow. is there.
[0014]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel pump for an internal combustion engine constituted by a regenerative pump, which has a function of accumulating vapor at a start end portion of a pump flow path. An internal combustion engine in which the start end of the flow path is enlarged in the axial direction of the casing, the vapor stored in the start end of the pump flow path can be gradually extracted, and a decrease in the discharge flow rate at high temperatures can be prevented as much as possible. To provide a fuel pump.
[0015]
[Means for Solving the Problems]
A first means of the present invention is to solve the above-mentioned problem.
An impeller in which a number of blade pieces and blade grooves are alternately formed on the outer periphery,
A casing that accommodates the impeller and forms an end-shaped annular pump flow path surrounding an outer peripheral portion of the impeller, and has a suction port and a discharge port communicating with a start end and an end of the pump flow path, respectively.
It is composed of a regeneration pump with
By immersing the suction port of the casing in liquid fuel for an internal combustion engine and rotating the impeller so that one side surface of the impeller faces upward, the liquid fuel flows from the suction port into the pump flow path. In the fuel pump for an internal combustion engine in which the sucked liquid fuel is increased in pressure while being sent toward the terminal end of the pump flow path and discharged from the discharge port,
The pump flow path is composed of a fuel introduction section on the start end side and a pressure increasing flow path section after the fuel introduction section,
Further, an inner portion of the fuel introduction portion on the side facing the one side surface of the impeller facing upward is formed so as to have a substantially constant depth deeper than the pressurized flow passage portion from a start end to a middle portion. In addition, a technical means is employed in which the portion having the constant depth is used as a vapor reservoir portion, and a portion from the end of the vapor reservoir portion to the pressurizing flow passage portion is formed to be gradually shallower.
[0016]
In the first means, the vapor mixed in the liquid fuel sucked into the pump flow path, or the vapor generated by a part of the liquid fuel vaporized when sucked into the pump flow path, Is stored in the vapor storage section of the fuel introduction section. Since the depth from the beginning to the end of the vapor reservoir is substantially constant, the vapor can be stored almost uniformly over the entire area of the vapor reservoir. For this reason, the vapor layer stored in the vapor storage section exists in a portion relatively close to the pressurized flow path section.
[0017]
Further, since the vapor reservoir has a constant depth, a sufficient internal volume can be secured without making the vapor reservoir too deep. For this reason, the vapor layer stored in the vapor storage part exists at a position relatively close to the impeller, and is easily drawn to the rotating impeller.
[0018]
Furthermore, since the portion from the end of the vapor reservoir to the boost channel portion of the fuel introduction portion is formed so as to be gradually shallower toward the boost channel portion, the bottom surface of the portion is an inclined surface. On the other hand, the vapor stored at the start end side of the fuel introduction section is more likely to flow to the pressurized flow path section side by the guiding action of the inclined surface.
[0019]
As described above, when the vapor is accumulated in the fuel introduction section, the vapor flows from the fuel introduction section toward the pressure increasing flow path portion little by little, and comes out of the vapor removal hole. Further, even if a vapor removal hole is not provided, a large amount of vapor does not flow into the pressurized flow path at a time, so that a decrease in the discharge flow rate due to vapor suction at a high temperature can be prevented as much as possible.
[0020]
A second means of the present invention for solving the above-mentioned problem is:
An impeller in which a number of blade pieces and blade grooves are alternately formed on the outer periphery,
A casing that accommodates the impeller and forms an end-shaped annular pump flow path surrounding an outer peripheral portion of the impeller, and has a suction port and a discharge port communicating with a start end and an end of the pump flow path, respectively.
It is composed of a regeneration pump with
By immersing the suction port of the casing in liquid fuel for an internal combustion engine and rotating the impeller so that one side surface of the impeller faces upward, the liquid fuel flows from the suction port into the pump flow path. In the fuel pump for an internal combustion engine in which the sucked liquid fuel is increased in pressure while being sent toward the terminal end of the pump flow path and discharged from the discharge port,
The pump flow path is composed of a fuel introduction section on the start end side and a pressure increasing flow path section after the fuel introduction section,
Furthermore, an inner portion of the fuel introduction portion on the side facing the one side surface facing upward of the impeller is formed at a middle portion at a deepest portion deeper than the boosting flow passage portion, and the deepest portion is formed as a vapor reservoir portion. At the same time, a technical means is employed in which the depth from the starting end to the vapor reservoir is gradually increased, and the depth from the vapor reservoir to the pressurized flow passage is gradually decreased.
[0021]
In the second means, the vapor mixed in the liquid fuel sucked into the pump flow path or the vapor generated by vaporizing a part of the liquid fuel when sucked into the pump flow path Is stored in the vapor storage section of the fuel introduction section. Since the vapor reservoir is located in the middle of the fuel introduction section, the vapor layer stored is located relatively close to the pressurized flow path.
[0022]
In addition, unlike the case where the vapor reservoir is present at the beginning of the fuel introduction section due to the presence of the vapor reservoir in the middle of the fuel introduction section, the impeller rotates the liquid fuel existing at the beginning of the fuel introduction section due to its rotation. And the vapor stored in the vapor storage section is easily drawn in.
Furthermore, since the portion from the end of the vapor reservoir to the pressurized flow passage in the fuel introduction portion is formed so as to be gradually shallower, the bottom surface of that portion is inclined, and is stored in the vapor reservoir. The vapor is easily flown into the pressurized flow path due to the guiding action of the inclined surface.
[0023]
From the above, when the vapor is stored in the vapor storage section of the fuel introduction section, the vapor flows little by little toward the pressurization flow path section, and the vapor is drawn by the vapor suction at a high temperature similarly to the first means. A decrease in the discharge flow rate can be minimized.
[0024]
The third means of the present invention sets the magnification of the depth of the vapor reservoir to the depth of the pressurized flow passage to 1.2 to 3 times in order to ensure the effect of preventing the discharge flow rate from decreasing. Things.
According to a fourth aspect of the present invention, in order to further enhance the effect of preventing the discharge flow rate from decreasing, the ratio of the depth of the vapor reservoir to the depth of the pressurizing flow path is set to 1.3 to 1.7 times. It is.
[0025]
That is, in the above-described first and second technical means, the same effect is not produced regardless of the size of the depth of the vapor reservoir. The graph of FIG. 9 shows the results obtained by experimentation on the relationship between the ratio of the depth of the vapor reservoir to the depth of the pressurized flow channel and the discharge flow rate.
[0026]
As is apparent from the figure, if the depth of the vapor reservoir is set in a range of 1.2 to 3 times the depth of the pressurizing flow path, it is effective to increase the discharge flow rate. It is understood that the third measure is effective.
Further, the discharge flow rate can be further increased by setting the depth of the vapor reservoir to 1.3 to 1.7 times the depth of the pressurizing flow path, and the fourth means of the present invention is further improved. It is understood that it is effective.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a fuel pump for an internal combustion engine of an automobile will be described with reference to FIGS.
As shown in FIG. 8, the fuel pump includes a motor unit 11 and a pump unit 12 driven by the motor unit 11. This fuel pump is arranged in a vertical axis type in a fuel tank (not shown) such that the motor unit 11 is on the upper side and the pump unit 12 is on the lower side.
[0028]
The motor unit 11 is a DC motor with a brush, and has a configuration in which a permanent magnet 14 is annularly arranged inside a housing 13 and an armature 15 is arranged inside the permanent magnet 14. A bearing holder 16 is fixed to the upper end of the housing 13 by press-fitting, and a radial bearing 18 that supports the upper end of the shaft 17 of the armature 15 is attached to the bearing holder 16.
[0029]
The interior of the housing 13 also functions as a chamber 19 for receiving liquid fuel discharged from the pump section 12 and sending it to a fuel injection device of an internal combustion engine (not shown). A cover end support 20 is fixed to the housing 13 by caulking at an upper portion of the bearing holder 16, and an insertion port 22 communicating with the chamber 19 through a groove 21 is formed in the cover end support 20. A tube (not shown) is inserted into the insertion port 22, and the high-pressure liquid fuel discharged into the chamber 19 is supplied to the fuel injection device of the internal combustion engine through the tube.
[0030]
On the other hand, the pump section 12 is composed of a regeneration pump. The pump section 12 has a casing body 23 integrally having a cylindrical peripheral wall section 23a and a side wall section 23b for closing one side surface of the cylindrical peripheral wall section 23a, and closes the other side surface of the cylindrical peripheral wall section 23a. It is composed of a casing cover 24 and an impeller 24. The casing main body 23 and the casing cover 24 are both formed by aluminum die casting.
[0031]
The casing main body 23 is press-fitted into the lower end of the housing 13 and fixed. The casing cover 24 is fixed to the lower end of the housing 13 by swaging or the like while being covered with the cylindrical peripheral wall 23a of the casing main body 23. . By combining the casing main body 23 and the casing cover 24 in this manner, a casing 27 is formed as an impeller chamber 26 in which the inner space of the cylindrical peripheral wall 23a is sealed.
[0032]
Here, the lower end of the shaft 17 of the armature 15, which is the drive shaft of the pump section 12, is inserted into a recess 28 formed in the center of the casing 27, and is inserted into a radial bearing 29 fitted in the recess 28. A downward thrust load is received by a thrust bearing 30 that is supported and fixed to the bottom surface of the recess 28.
[0033]
The impeller 25 is integrally formed in a substantially disk shape by, for example, a phenol resin containing glass fiber, PPS, or the like. As shown in FIG. They are formed alternately along the circumferential direction. The blade piece 31 and the blade groove 32 are present on both sides of the partition wall 33 at the axial center.
[0034]
The impeller 25 is rotatably housed in the impeller chamber 26. As shown in FIG. 7, a substantially D-shaped fitting hole 34 formed in the center of the impeller 25 is formed in the D cut portion 17a of the shaft 17 in the axial direction. It is slidably fitted. As a result, the impeller 25 is rotationally transmitted from the shaft 17 and rotates integrally with the shaft 17, but is freely movable in the axial direction with respect to the shaft 17.
[0035]
The casing cover 24 located on the lower side among the components of the casing 27 is formed with a vertically extending suction port 35, the lower end of which is opened into the liquid fuel in the fuel tank. On the other hand, a vertically extending discharge port 36 is formed in the side wall 23b of the casing body 23 located on the upper side, and the upper end thereof is opened in the chamber 19. An end-shaped annular pump flow path 37 connecting the suction port 35 and the discharge port 36 is formed in the inner peripheral portion of the impeller chamber 28, and the blade piece 31 of the impeller 25 projects into the pump flow path 37. ing. Hereinafter, of both ends of the pump flow path 37, the end on the suction port 35 side is referred to as a start end, and the end on the discharge port 36 side is referred to as a terminal end.
[0036]
In the pump flow path 37, a portion on the outer peripheral side of the blade piece 31 is formed by forming the inner diameter of the cylindrical peripheral wall portion 23a of the casing main body 23 to be larger than the outer dimension of the impeller 25. As shown in FIGS. 4 and 5, both side portions are formed by forming closed annular grooves 38 and 39 on the inner surface of the side wall 23 b of the casing main body 23 and the inner surface of the casing cover 24.
[0037]
The portion of the cylindrical peripheral wall portion 23a which is located between the suction port 35 and the discharge port 36 and which is left after the inner diameter is enlarged protrudes in an arc shape toward the impeller chamber 26. The portion is a radial seal portion 40 which is close to the outer peripheral surface of the impeller 25 with a very small gap. The radial seal portion 40 seals between the suction port 35 and the discharge port 36 to prevent leakage of liquid fuel from the discharge port 36 on the high pressure side to the suction port 35 on the low pressure side.
[0038]
The inner side surfaces of the side wall portion 23b of the casing main body 23 and the inner side surface of the casing cover 24 are formed as axial seal surfaces 41 and 42 which are close to the upper and lower inner side surfaces of the impeller 25 with a very small gap. The axial seal surfaces 41 and 42 seal the gap between the pump flow channel 37 and the concave portion 28 formed at the center of the casing 27, thereby preventing leakage of liquid fuel between them.
[0039]
Thus, the pump flow path 37 is provided with a fuel introduction section 43 (shown by α in the drawing) on the start end side and a boosting flow path section 44 (from β in FIG. 2) extending from the end of this fuel introduction section 43 to the start end of the discharge port 36. Shown). The latter pressurized flow path portion 44 is a region having a fixed flow passage size capable of exhibiting a sufficient pumping action and having a constant flow passage cross-sectional area, and the liquid fuel mainly flows while flowing through the pressurized flow passage portion 44. The pressure is sufficiently increased by the impeller 25.
[0040]
On the other hand, the fuel introduction section 43 functions to smoothly flow the liquid fuel sucked from the suction port 35 having a large flow path cross-sectional area into the pressurized flow path section 44 having a small flow path cross-sectional area. For this purpose, the starting end portions of the upper and lower annular grooves 38 and 39 constituting the fuel introduction portion 43 are formed such that the radial width is wide at the starting end, and a predetermined length from the starting end toward the pressurizing flow path portion 44 side. The liquid fuel is formed so as to be gradually narrower in the width range, so that the liquid fuel flows smoothly from the suction port 35 having a larger opening width to the pressure increasing flow path portion 44 having a smaller width.
[0041]
Further, the internal volume of the fuel introduction section 43 is enlarged so as to function as a vapor storage section. When the fuel pump is disposed in the fuel tank in a vertical axis type, the inner volume of the fuel pump expands in a direction away from the impeller 25 (upward) when the inner side of the fuel pump is opposed to one of the side faces facing upward. It is done by doing.
[0042]
That is, as shown in FIG. 1, the starting end side of the annular groove 39 formed in the casing cover 24 constitutes an inside portion of the fuel introduction portion 43 facing the lower side surface of the impeller 25, and the casing body 23 The start end side of the annular groove 38 formed at the inner side of the fuel introduction portion 43 opposes the side surface on the upper side of the impeller 25. The starting end of the annular groove 39, which is the lower inner portion of the fuel introduction portion 43, is formed at the same depth as the portion forming the lower inner portion of the pressurizing flow passage portion 41. Therefore, the annular groove 39 has the same depth from the beginning on the inlet 35 side to the end on the discharge port 36 side, with no difference in depth between the fuel introduction part 43 and the pressurized flow path part 44.
[0043]
On the other hand, the annular groove 38 of the casing main body 23, which is the upper inside portion of the fuel introduction portion 43, has a depth D 1 from the beginning to the middle of the fuel introduction portion 43, which is the upper inside portion of the pressurizing flow passage portion 44. Is formed at a substantially constant depth that is deeper than the depth D2 of the portion that constitutes the pressure rising portion, and thereafter it is formed so as to be gradually shallower up to the start end of the pressurized flow passage portion 44. Here, a portion of the fuel introduction portion 43 having a constant depth is referred to as a vapor reservoir portion 45, and a portion subsequent thereto is referred to as a guide portion 46.
[0044]
Therefore, the bottom surface 45 a of the vapor reservoir 45 in the fuel introduction portion 43 is substantially parallel to the axial seal surface 41 of the casing main body 23, and the bottom surface of the guide portion 46 thereafter faces toward the pressurizing flow passage portion 44. It is formed on an inclined surface 46a that is inclined so as to descend.
[0045]
Then, at a position slightly entering the pressurized flow passage portion 44 from the end of the fuel introduction portion 43, the casing cover 24 extends from the bottom surface of the annular groove 39 of the casing cover 24 constituting the lower inner portion of the pressurized flow passage portion 44. Is formed in the fuel tank, and the vapor stored in the vapor storage part 45 flows out of the vapor discharge hole 47 into the fuel tank when the vapor flows into the pressurized flow path part 44. It has become.
[0046]
Here, the dimensions of each part of the pump channel 37 will be described.
First, if the length of the fuel introduction section 43 is short, the function cannot be sufficiently exhibited, and if the length is long, the length of the fuel pressurization section 44 becomes short, resulting in insufficient pressurization of the liquid fuel. Therefore, it is preferable that the length of the fuel introduction section 43 be 5 to 30% of the length of the pressurization flow path section 44. In this embodiment, the area angle α of the fuel introduction section 43 is 70 °, The region angle β of the portion 44 is set to 233 °.
[0047]
In the fuel introduction section 43, the area angle γ of the vapor reservoir section 45 is set to 48 °, and the area angle δ of the guide section 46 is set to 22 °. In this embodiment, since the diameter D of the pump flow path 37 is set to 28.5 mm, the flow path length of the vapor reservoir 45 is about 11.9 mm, and the flow path length of the guide section 46 is about 5.5. 5 mm.
[0048]
Further, the depth D1 of the vapor reservoir section 45 is set to be 1.2 to 3 times the depth D2 of the pressurizing flow path section 41. Among them, as understood from the description of FIG. It is particularly preferable to set the ratio to 0.3 to 1.7 times. In this embodiment, since the depth D2 of the pressurizing flow passage 41 is set to 1 mm, the depth of the vapor reservoir 45 is set to 1.2 to 3 mm, particularly 1.3. It is preferable to set it to ~ 1.7 mm.
[0049]
Next, the operation of the above configuration will be described.
When the motor unit 11 starts, the impeller 25 is rotated by the shaft 17 of the armature 16. As a result, the blade piece 31 of the impeller 25 rotates in the direction indicated by the arrow A in FIG. 7 along the pump flow path 37 to generate a pumping action, and the liquid fuel in the fuel tank (not shown) flows from the suction port 35 to the pump flow path 37. Inhale into. The liquid fuel sucked into the pump channel 37 is sucked into the blade groove 32 as shown by arrows B and C in FIG. 6, and is sent out into the pump channel 37 by receiving kinetic energy from the blade piece 31. By repeating the above, the pressure flows through the pump flow path 37 toward the discharge port 36 at the terminal end while the pressure increases. Then, the high-pressure liquid fuel is finally fed from the discharge port 36 to the fuel injection device of the internal combustion engine.
[0050]
By the way, the liquid fuel in the fuel tank has a higher tendency to vaporize and generate bubbles as the temperature becomes higher. Therefore, bubbles (vapor) may be mixed in the liquid fuel sucked into the pump flow path 37 of the fuel pump, and the liquid fuel sucked into the pump flow path 37 may be sucked into the suction port 35. Partial vaporization occurs due to negative pressure in the part.
[0051]
In this manner, the vapor mixed in the liquid fuel sucked into the pump flow path 37 and the vapor generated by vaporizing a part of the liquid fuel sucked into the pump flow path 37 are liquid fuel. The fuel floats inside and is stored in the vapor storage section 45 of the fuel introduction section 43.
[0052]
Since the vapor reservoir portion 45 is formed at a constant depth over a predetermined length range from the start end of the fuel introduction portion 44, the start end is made deepest as shown in FIG. Unlike the structure formed so as to be gradually shallower, the depth does not have to be so large in order to secure the necessary internal volume for the vapor reservoir 45. Thus, the vapor reservoir 45 can be made relatively shallow, so that the vapor stored in the vapor reservoir 45 is located near the impeller 25. In addition, the vapor stored in the vapor storage section 45 having a constant depth spreads over the entire vapor storage section 45 and comes closer to the pressure increasing flow path section 44.
[0053]
From the above, the vapor stored in the vapor reservoir 45 is attracted to the impeller 25 by the negative pressure generated with the rotation of the impeller 25, and moves from the vapor reservoir 45 to the guide 46 little by little. I will be going. At this time, since the bottom surface (upper surface) of the guide portion 46 is the inclined surface 46a, the vapor is easily moved to the pressure increasing flow path portion 44 along the inclined surface 46a of the guide portion 46 by the rotation of the impeller 25. Since the pressure of the liquid fuel is increased in the process of moving through the guide portion 46, the vapor that moves to the pressurizing flow passage portion 44 little by little is extracted from the vapor removal hole 47 by the pressure. go.
[0054]
The vapor stored in the vapor storage part 45 flows toward the pressure increasing flow path part 44 side by being guided by the guide part 46 from the vapor storage part 45 little by little, and is drawn out from the vapor discharge hole 47. become. Therefore, there is no possibility that a large amount of vapor is accumulated in the vapor reservoir 45, and the vapor accumulated in the vapor reservoir 45 flows toward the pressure increasing flow path 44 at a time so as to follow the rotation of the impeller 25. It is possible to prevent the occurrence of a situation of going down as much as possible. As a result, the vapor does not flow into the pressurizing flow path portion 44, and even if the vapor flows, the amount becomes small. Therefore, there is no possibility that the pumping action of the impeller 25 is reduced.
[0055]
For this reason, even when the liquid fuel containing a large amount of vapor is sucked into the pump flow path 37 at a high temperature and becomes negative pressure when further sucked, the liquid fuel generates vapor. It is possible to prevent the vapor from being extracted from the vapor extraction hole 47 and flowing into the pressurized flow path section 44, and it is possible to effectively prevent the discharge flow rate from decreasing at high temperatures.
[0056]
FIG. 9 shows the relationship between the depth D1 and the discharge flow rate by variously changing the magnification (D1 / D2) of the depth D1 of the vapor reservoir portion 45 with respect to the depth D2 of the pressurizing flow passage portion 44 in the present invention. The results of the experiment are shown. In this experiment, the reed vapor pressure was 0.88 kg / cm ² The fuel pump was arranged in a vertical axis in the gasoline of No. 1, and the fuel pump was operated under a driving condition capable of obtaining a discharge flow rate of 145 L / h at a discharge pressure of 350 kPa. Then, in this operating state, the temperature of the gasoline was gradually increased from the room temperature to determine the discharge flow rate at each temperature, and the lowest discharge flow rate was shown in FIG.
[0057]
The above-mentioned Reid vapor pressure refers to the vapor pressure of gasoline at a specified temperature (37.8 ° C.). The test for determining the Reid vapor pressure is performed by sealing the sample in a pressure vessel and measuring the pressure at a specified temperature. The higher the Reid vapor pressure, the easier it is to vaporize, and the lower the Reid vapor pressure, the worse the startability of the internal combustion engine. In the case of regular gasoline, the reed vapor pressure is generally 0.6 to 0.7 kgf / cm. ² It is.
[0058]
As is apparent from FIG. 9, when D1 / D2 is set in the range of 1.2 to 3, the minimum discharge flow rate becomes higher than when D1 / D2 is 1. In other words, when D1 / D2 is set in the range of 1.2 to 3, it can be said that the amount of decrease in the discharge flow rate is smaller than that of 145 L / h which should be obtained from the driving conditions, and this is because Means that the effect of preventing the decrease in the discharge flow rate due to the vapor suction is high.
[0059]
Further, when D1 / D2 is set to 1.3 to 1.7, the minimum discharge flow rate is further increased, and it is possible to suppress a decrease in the discharge flow rate even at a high temperature under a high output of the internal combustion engine. It can be understood that the fuel pump can satisfy the requirement sufficiently.
[0060]
When D1 / D2 is increased, the internal volume of the vapor reservoir 45 is increased, and a large amount of vapor can be stored. Therefore, a decrease in the discharge flow rate should be prevented more effectively. According to the experimental results shown, the D1 / D2 decreases as the ratio increases to 2.2 and 3. This is probably because, when D1 / D2 is increased, the angle of the inclined surface 46a, which is the bottom surface of the guide portion 46, is increased, and the guiding action is reduced. Therefore, it is understood that there should be no step between the vapor reservoir 45 and the pressurized flow passage 44, and it is better to use the guide 46 having the inclined surface 46a as in this embodiment. It is understood that the gentle inclination of the surface 46a is also effective for preventing vapor suction.
[0061]
FIG. 10 shows another embodiment of the present invention. This embodiment is different from the above-described embodiment in that the upper annular groove 38 of the fuel introduction portion 43 that forms the upper inside portion of the impeller 25 is formed at the middle portion at the deepest portion deeper than the pressurized flow passage portion 44. The deepest portion is formed as the vapor reservoir portion 48, and is formed so as to be gradually deeper from the start end to the vapor reservoir portion 48. It is where it was formed.
[0062]
A portion from the vapor reservoir 48 to the start end of the pressurizing flow passage 44 is a guide portion 49 having an inclined surface 49 whose bottom surface (upper surface) is inclined so as to descend toward the pressurizing flow passage 44.
Also in this embodiment, the depth D1 of the vapor reservoir 48 is 1.2 to 3 times, preferably 1.2 to 3 times the depth D2 of the pressurizing flow passage 44, for the same reason as in the first embodiment. It is set to be 1.7 times.
[0063]
In such a configuration, the vapor contained in the liquid fuel sucked into the pump flow path 37 or the vapor generated when a part of the liquid fuel is vaporized when drawn into the pump flow path 37 is Is stored in a vapor storage section 48 which is the deepest part of the fuel introduction section 43. Since the vapor reservoir 48 is located in the middle of the fuel introduction section 43, the vapor reservoir 48 is not so far away from the pressurizing flow path section 44, and is far from the start end of the fuel introduction section 43.
[0064]
The liquid fuel in the fuel introduction section 43 does not yet sufficiently receive the suction action of the impeller 25 at the start end thereof, but gradually receives the suction action of the impeller 25 from the start end to the end end of the fuel introduction section 43. . Considering this fact, the fact that the vapor reservoir 48 is at a certain distance from the start end of the fuel introduction unit 43 as described above means that the vapor stored in the vapor reservoir 48 receives the suction action of the impeller 25 better. As a result, the vapor is withdrawn little by little from the vapor reservoir 48, and flows toward the pressure increasing flow path 44 under the guide action of the inclined surface 49a of the guide 49, and from the vapor discharge hole 47 to the fuel tank. It is extracted. Therefore, even with the configuration as in this embodiment, the same effect as in the above-described one embodiment can be obtained.
[0065]
The present invention is not limited to the embodiment described above and shown in the drawings. For example, the present invention may be applied to a first-stage pump flow path in a multi-stage pump, and various modifications may be made without departing from the scope of the invention. Can be implemented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a casing, showing one embodiment of the present invention, which is developed along a line II in FIG. 2;
FIG. 2 is a plan view of a casing body.
FIG. 3 is a plan view of a casing cover.
FIG. 4 is a perspective view of a casing body.
FIG. 5 is a perspective view of a casing cover.
FIG. 6 is an enlarged sectional view of a pump flow path portion.
FIG. 7 is a cross-sectional view of a pump section.
FIG. 8 is a longitudinal sectional view of the entire fuel pump.
FIG. 9 is a graph showing an experimental result in which a relationship between a depth ratio of a fuel introduction section to a pressurized flow path section and a minimum discharge flow rate is obtained.
FIG. 10 is a diagram corresponding to FIG. 1, showing another embodiment of the present invention.
FIG. 11 is a diagram corresponding to FIG. 1 showing a conventional example.
[Explanation of symbols]
In the figure, 11 is a motor unit, 12 is a pump unit, 23 is a casing body, 24 is a casing cover, 25 is an impeller, 27 is a casing, 31 is a blade piece, 32 is a blade groove, 35 is a suction port, and 36 is a discharge port. 37, a pump flow path, 43, a fuel introduction section, 44, a pressurization flow path section, 45, a vapor storage section, 46, a guide section, 47, a vapor removal hole, 48, a vapor storage section, and 49, a guide section.

Claims (4)

An impeller in which a number of blade pieces and blade grooves are alternately formed on the outer periphery,
A casing that accommodates the impeller, forms an end-shaped annular pump flow path surrounding the outer peripheral portion of the impeller, and forms a suction port and a discharge port communicating with a start end and an end of the pump flow path, respectively. It is composed of a regeneration pump equipped with
By immersing the suction port of the casing in liquid fuel for an internal combustion engine and rotating the impeller so that one side surface of the impeller faces upward, the liquid fuel flows from the suction port into the pump flow path. In the fuel pump for an internal combustion engine in which the sucked liquid fuel is increased in pressure while being sent toward the terminal end of the pump flow path and discharged from the discharge port,
The pump flow path is composed of a fuel introduction section on the start end side and a pressure increasing flow path section after the fuel introduction section,
Further, an inner portion of the fuel introduction portion on the side facing the one side surface of the impeller facing upward is formed so as to have a substantially constant depth deeper than the pressurized flow passage portion from a start end to a middle portion. The fuel pump for an internal combustion engine is characterized in that the portion having a constant depth is used as a vapor reservoir, and that a portion from the end of the vapor reservoir to the pressure-raising passage is gradually reduced in depth. An impeller in which a number of blade pieces and blade grooves are alternately formed on the outer periphery,
A casing that accommodates the impeller, forms an end-shaped annular pump flow path surrounding the outer peripheral portion of the impeller, and forms a suction port and a discharge port communicating with a start end and an end of the pump flow path, respectively. It is composed of a regeneration pump equipped with
By immersing the suction port of the casing in liquid fuel for an internal combustion engine and rotating the impeller so that one side surface of the impeller faces upward, the liquid fuel flows from the suction port into the pump flow path. In the fuel pump for an internal combustion engine in which the sucked liquid fuel is increased in pressure while being sent toward the terminal end of the pump flow path and discharged from the discharge port,
The pump flow path is composed of a fuel introduction section on the start end side and a pressure increasing flow path section after the fuel introduction section,
Furthermore, an inner portion of the fuel introduction portion on the side facing the one side surface facing upward of the impeller is formed at a middle portion at a deepest portion deeper than the boosting flow passage portion, and the deepest portion is formed as a vapor reservoir portion. A fuel pump for an internal combustion engine, wherein the fuel pump is formed so as to be gradually deeper from a starting end to the vapor reservoir, and is formed so as to be gradually shallower from the vapor reservoir to the pressurizing flow passage. 3. The fuel pump for an internal combustion engine according to claim 1, wherein the depth of the vapor reservoir is set to be 1.2 to 3 times as large as the depth of the pressurizing flow path. 3. The fuel pump for an internal combustion engine according to claim 1, wherein the depth of the vapor reservoir is set to 1.3 to 1.7 times as large as the depth of the pressurizing flow path. .

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