JPH0519556U - Fuel pump - Google Patents

Abstract

(57) [Summary] [Purpose] To effectively eliminate the vapor in the Wesco type two-stage fuel pump and improve the performance at high temperatures. [Structure] In a Wesco type two-stage fuel pump, a passage expansion portion 45 having an increased passage cross-sectional area is provided in the middle of a low pressure side fuel passage 30a. On the wall of the low-pressure side pump chamber 9a, a vapor discharge jet 41 is provided which connects the downstream portion of the passage expanding portion 45 and the outside of the pump chamber. When the fuel flows to the passage expanding portion 45 in the low pressure side fuel passage 30a,
Vapor is positively generated due to the increase in the passage cross-sectional area. The vapor is jet 4 for vapor discharge
1 is discharged to the outside of the pump room.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fuel pump used in an automobile or the like, particularly a Wesco type fuel pump.

[0002]

[Prior Art]

 Conventionally, as this type of Wesco type fuel pump, a low pressure side pump chamber and a high pressure side pump chamber each having an impeller, and a substantially C-shaped low pressure side fuel passage and a high pressure side formed by each pump chamber and each impeller are provided. A fuel passage, a fuel inlet communicating with the start end of the low pressure side fuel passage, a communication hole communicating the end of the low pressure side fuel passage with the start end of the high pressure side fuel passage, and a fuel intake end with the end of the high pressure side fuel passage. A two-stage fuel pump having a fuel discharge port that communicates is known. In order to prevent the fuel supply by vapor such as fuel vapor generated in the pump chamber, that is, to prevent the phenomenon of vapor lock, the low pressure side fuel passage and the outside of the pump chamber are formed on the wall of the low pressure side pump chamber. In some cases, a vapor discharging jet that communicates with the above is provided, and the vapor is discharged from the discharging jet to the outside of the pump chamber. Such a conventional fuel pump is proposed by, for example, Japanese Utility Model Laid-Open No. 63-160387 previously proposed by the same applicant. Further, examples of one-stage fuel pumps provided with a jet for vapor discharge include those disclosed in, for example, JP-A-60-79193 and JP-A-62-214294.

[0003]

[Problems to be solved by the device]

 According to the conventional method, the vapor generated upstream of the vapor discharge jet at a high temperature is discharged to some extent from the discharge jet, but the vapor component at that temperature still remains in the fuel in the fuel passage. Therefore, vapor is likely to be generated again while passing downstream of the vapor discharge jet, and the fuel passage is blocked by the vapor, so that the performance at high temperature is deteriorated.

Therefore, the present invention has been made to solve the above-mentioned problems, and the purpose thereof is to effectively eliminate the vapor in the Wesco type two-stage fuel pump and improve the high temperature performance. To provide a fuel pump.

[0005]

[Means for Solving the Problems]

 The fuel pump of the present invention for solving the above-mentioned problems includes a low pressure side pump chamber and a high pressure side pump chamber each having an impeller, and a substantially C-shaped low pressure side fuel passage and a high pressure side formed by each pump chamber and each impeller. A fuel passage, a fuel intake port communicating with the starting end of the low pressure side fuel passage, a communication hole communicating the end of the low pressure side fuel passage with the starting end of the high pressure side fuel passage, and a communication hole communicating with the end of the high pressure side fuel passage. In the fuel pump including the fuel discharge port, the low pressure side fuel passage is provided with a passage enlarged portion whose passage cross-sectional area increases in the middle of the passage, and the low pressure side pump chamber wall has the passage enlarged portion. A vapor discharge jet is provided to connect the downstream part of the pump to the outside of the pump chamber. Further, a vapor return jet that connects the high pressure side fuel passage and the low pressure side fuel passage is provided on a partition wall between the low pressure side pump chamber and the high pressure side pump chamber, and the vapor return jet for the vapor return jet is provided. Is preferably connected to the low pressure side fuel passage upstream of the vapor discharge jet.

[0006]

[Action]

 According to the above means, the fuel pumped from the fuel intake port is sent to the high pressure side fuel passage through the communication hole through the low pressure side fuel passage by the rotation of the impeller, and then the fuel of the pump cover is passed through the fuel passage. It is discharged from the discharge port. Then, when the fuel flows to the passage enlarged portion in the low pressure side fuel passage, the vapor is positively generated due to the increase in the passage cross-sectional area. The vapor generated here is discharged to the outside of the pump chamber through a vapor discharging jet located downstream of the enlarged passage. At this time, since the vapor discharge jet is positioned before the passage cross-sectional area decreases, the vapor is blocked and the vapor discharge jet is smoothly discharged. Be seen. Therefore, there is almost no vapor component in the fuel flowing downstream of the vapor discharge jet. Also, in the case where the vapor return jet is installed, the vapor that could not be exhausted by the vapor exhaust jet under a rather severe condition and the vapor generated downstream of the vapor exhaust jet are in both fuel passages. After being returned from the high-pressure side fuel passage to the low-pressure side fuel passage through the vapor return jet due to the pressure difference, the vapor is discharged from the vapor discharge jet to the outside of the pump chamber.

[0007]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. [First Embodiment] First, an outline of a fuel pump will be described with reference to FIG. 5 showing a cross-sectional view thereof. A cylindrical metal housing 1 has a motor part 2 incorporated in its upper part and a pump part 3 incorporated in its lower part. A synthetic resin motor cover 5 is attached to the upper end surface of the housing 1. A synthetic resin pump cover 6, a plate 24, and a pump body 7 are attached to the lower end surface of the housing 1. A motor chamber 8 is formed between the motor cover 5 and the pump cover 6 in the housing 1, and a high pressure chamber side pump chamber 9b is formed between the pump cover 6 and the plate 24. A low pressure chamber side pump chamber 9 a is formed between the pump body 7 and the pump body 7. Further, the plate 24 forms a wall that divides the two pump chambers 9a and 9b according to the present invention.

In the motor section 2, an armature 10 is arranged in the motor chamber 8. The upper and lower ends of the shaft 12 of the armature 10 are rotatably supported by the motor cover 5 and the pump cover 6 via bearings 13 and 14, respectively. A pair of magnets 15 are fixed to the inner peripheral surface of the housing 1 at a predetermined distance from the outer peripheral surface of the armature 10. A brush 16 which is in sliding contact with the commutator 10a of the armature 10 is installed in the motor cover 5 in a state of being biased by a spring 17. The brush 16 is electrically connected to an external connection terminal (not shown) via a choke coil 18. The motor cover 5 is provided with a fuel outlet 20 to which a fuel supply pipe (not shown) leading to a fuel injection valve of an automobile engine is connected. A check valve 21 for preventing a backflow of fuel is installed in the fuel outlet 20 in a state of being biased in a closing direction by a spring 22.

In the pump section 3, an impeller 25 is arranged in each of the pump chambers 9a and 9b. Both impellers 25 are connected to the lower end of the shaft 12 of the armature 10 and are driven to rotate by the drive of the motor unit 2. Each impeller 25 has a disk shape as shown in the plan view of FIG. 7, and the blades 25a are formed by a large number of grooves 25b provided on the outer peripheral portions of both front and back surfaces thereof. Further, the impeller 25 is formed with a proper number (six in the figure) of opening holes 25c located on the inner and outer circumferential lines at substantially equal intervals.

Further, in FIG. 5, the fuel intake port 26 is provided in the pump body 7, and the fuel discharge port 27 is provided in the pump cover 6. A low pressure side fuel passage 30a and a high pressure side fuel passage 30b, which are substantially C-shaped, are formed by the pump chambers 9a and 9b and the impellers 25, respectively. The low pressure side fuel passage 30a is formed so as to straddle the pump body 7 and the plate 24, and the high pressure side fuel passage 30b is formed so as to straddle the plate 24 and the pump cover 6. The starting end of the low-pressure side fuel passage 30a communicates with the fuel intake port 26, and the ending end of the low-pressure side fuel passage 30a communicates with the starting end of the high-pressure side fuel passage 30b through a communication hole 28. The end of the fuel passage 30b communicates with the fuel discharge port 27, and the fuel suction port 26 to the fuel discharge port 27 communicate with each other in a spiral shape. Although the fuel intake port 26, the fuel discharge port 27, and the communication hole 28 are shown to be on the same line in FIG. 5, they are actually in a positional relationship in which they are displaced from each other by a predetermined angle.

Next, regarding the shapes of the wall surfaces of the pump body 7, the plate 24, and the pump cover 6 that form the fuel passages 30a and 30b, FIG. Will be described in detail with reference to FIGS. As shown in FIG. 6, a lower passage groove 31 that forms a substantially lower half portion of the low pressure side fuel passage 30a is provided on a wall surface (upper surface) of the pump body 7. As shown in the plan view of FIG. 1, a predetermined range is formed as a passage expansion portion 45 in the passage groove 31 in the middle of the passage of the low pressure side fuel passage 30a so that the passage width is doubled. Has been done. More specifically, the outer peripheral edge of the lower passage groove 31 has a series of shapes, and a recess 45 a is formed on the inner periphery thereof between the step portions 46 and 47 due to the formation of the passage enlarged portion 45. Further, as shown in FIGS. 1 and 6, a rising wall 7a having a height substantially equal to the thickness of the impeller 25 is formed in an annular shape on the outer peripheral edge of the pump body 7.

Further, as shown in FIG. 6, the lower wall surface (lower surface) of the plate 24 is provided with an upper passage groove 33 that forms a substantially upper half of the low pressure side fuel passage 30 a. There is. The passage groove 33 is substantially symmetrical to the lower passage groove 31 as shown in the plan view of FIG. The communication hole 28 is formed in a substantially elliptical shape that is long in the circumferential direction of the plate 24.

Further, as shown in FIG. 6, a lower passage groove 35 that forms a substantially lower half portion of the high pressure side fuel passage 30 b is provided on the upper wall surface (upper surface) of the plate 24. .. A plan view of the passage groove 35 is shown in FIG. As shown in FIG. 6, the wall surface (lower surface) of the pump cover 6 is provided with an upper passage groove 37 that forms a substantially upper half of the high pressure side fuel passage 30b. The passage groove 37 is formed in a substantially symmetrical shape with the lower passage groove 35 of the plate 24 as shown in the bottom view of FIG. Further, as shown in FIGS. 4 and 6, a rising wall 6a having a height substantially equal to the wall thickness of the impeller 25 is formed on the outer peripheral edge of the pump cover 6 in an annular shape. The fuel discharge port 27 is also formed in a substantially elliptical shape that is long in the circumferential direction of the cover 6 like the communication hole 28.

However, as shown in FIGS. 1 and 6, the pump body 7 has a vapor discharging jet adjacent to the upstream side of the step portion 47 in the enlarged passage portion 45 of the lower passage groove 31. 41 is open. Further, the discharge jet 41 is located on the same circumferential line as the circumferential line where the opening hole 25c outside the impeller 25 is located, and has substantially the same diameter as the opening hole 25c. The discharge jet 41 of this example is located at an angle θ (about 250 ° in this example) in the flow direction from the fuel suction port 26.

As shown in FIGS. 3 and 6, the plate 24 has a lower surface at a predetermined angle from the communication hole 28 at the inner peripheral edge of the lower passage groove 35 on the upper surface thereof. A vapor return jet 43 penetrating the upper passage groove 33 is opened. The vapor returning jet 43 is connected to the low pressure side fuel passage 30a upstream of the vapor discharging jet 40.

In the fuel pump, the impeller 25 of the pump unit 3 is rotated as the motor unit 2 is driven by a battery (not shown) of an automobile or the like as a power source. As a result, the fuel in the fuel tank is pumped from the fuel suction port 26 to the low pressure side pump chamber 9a. This pumped fuel is sent to the high pressure side fuel passage 30b through the communication hole 28 through the low pressure side fuel passage 30a by the rotation of the impeller 25, and then through the fuel passage 30b, the fuel discharge port of the pump cover 6. It is discharged from 27 and enters the motor chamber 8, and then is discharged from the fuel outlet 20 of the motor cover 5.

According to the above-described fuel pump, when the fuel passes through the step portion 46 in the low pressure side fuel passage 30a and flows into the passage enlarged portion 45, the vapor is increased due to the rapid increase in the passage cross-sectional area. It is actively generated. The vapor generated here is discharged to the outside of the pump chamber by the vapor discharging jet 41 located downstream of the passage expanding portion 45. At this time, since the vapor discharge jet 41 is positioned before the cross-sectional area of the passage is sharply reduced, the vapor is blocked, so that the vapor discharge jet 41 can be prevented. Is discharged smoothly. Therefore, the vapor component in the fuel flowing downstream of the vapor discharge jet 41 is almost eliminated, and the high temperature performance is improved.

Under considerably severe conditions, the vapor that cannot be completely discharged by the vapor discharging jet 41 and the vapor that is generated downstream of the vapor discharging jet 41 are caused by the pressure difference between the fuel passages 30a and 30b. After returning from the high pressure side fuel passage 30b to the low pressure side fuel passage 30a through the vapor returning jet 43, it is discharged from the vapor discharging jet 41 to the outside of the pump chamber. Therefore, the vapor is eliminated even more effectively.

Further, since the discharging jet 41 is located on the same circumferential line as the circumferential line where the opening hole 25c outside the impeller 25 is located, the vapor returned from the vapor returning jet 43 passes through the opening hole 25c. It flows smoothly to the jet 41 and is discharged.

Second Embodiment A second embodiment will be described. Since this embodiment is a modification of a part of the embodiment, the different configuration will be described in detail, and the description overlapping with that of the first embodiment will be omitted. As shown in the plan view of the pump body in FIG. 8, in this embodiment, the lower passage groove 31 of the pump body 7 of the first embodiment is provided with the passage enlarged portions 45 at two places. Along with this, the vapor discharging jet 41 and the step portion 47 are formed in the same manner as described above.

[0021]

[Effect of the device]

 The effects of the present invention are as follows. That is, according to the fuel pump of the first aspect, since the vapor is positively generated and then discharged to the outside of the pump chamber, the vapor can be effectively removed, and the vapor is discharged downstream from the vapor discharge jet. As a result of almost no vapor component in the fuel flowing through, the performance at high temperature is enhanced. Further, according to the fuel pump of claim 2, since the vapor existing downstream of the vapor discharging jet is discharged through the vapor returning jet and the vapor discharging jet under a considerably severe condition, the vapor is further enhanced. Effectively eliminated.

[Brief description of drawings]

FIG. 1 is a plan view of a pump body according to a first embodiment.

FIG. 2 is a bottom view of the plate.

FIG. 3 is a plan view of a plate.

FIG. 4 is a bottom view of the pump cover.

FIG. 5 is an overall sectional view of a fuel pump.

FIG. 6 is a sectional view showing a main part of a fuel pump.

FIG. 7 is a plan view of the impeller.

FIG. 8 is a plan view of the pump body showing the second embodiment.

[Explanation of symbols]

 9a Low pressure side pump chamber 9b High pressure side pump chamber 25 Impeller 26 Fuel inlet 27 Fuel discharge port 28 Communication hole 30a Low pressure side fuel passage 30b High pressure side fuel passage 41 Vapor discharge jet 43 Vapor return jet 45 Passage expansion part

Claims (2)

[Scope of utility model registration request] 1. A low pressure side pump chamber and a high pressure side pump chamber each having an impeller, a substantially C-shaped low pressure side fuel passage and a high pressure side fuel passage formed by each pump chamber and each impeller, and the low pressure side. A fuel intake port communicating with the start end of the fuel passage, a communication hole communicating the end of the low pressure side fuel passage with the start end of the high pressure side fuel passage, and a fuel discharge port communicating with the end of the high pressure side fuel passage. In the fuel pump, the low-pressure side fuel passage is provided with a passage enlarged portion whose passage cross-sectional area increases in the middle of the passage, and a wall of the low-pressure side pump chamber is provided with a downstream portion of the passage enlarged portion and outside the pump chamber. A fuel pump that is provided with a vapor discharge jet that communicates with each other. 2. A vapor return jet for communicating the high pressure side fuel passage and the low pressure side fuel passage is provided on a partition wall between the low pressure side pump chamber and the high pressure side pump chamber, and for the vapor return thereof. The fuel pump according to claim 1, wherein a jet is connected to the low pressure side fuel passage upstream of the vapor discharging jet.