JP2774127B2 - Electric pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric pump.

(Prior art) Conventionally, as an electric pump, a rotary driven impeller,
A pump casing surrounding the impeller, wherein the pump casing includes an inlet and an outlet provided at appropriate positions in the circumferential direction, and an inlet surrounding an impeller provided at an outer peripheral portion of the impeller. And a so-called Wesco-type electric pump having a flow path groove that forms a circumferential flow path from the section to the outlet section. Such a Wesco-type electric pump is used in a vehicle such as an automobile. It is widely used as a fuel pump for pumping fuel from inside a tank and supplying it to an engine.

In such a Wesco type electric pump, when a fluid collides with a partition between an inlet and an outlet of the pump casing, noise in a high frequency band determined by the number of impeller blades times the number of impeller revolutions is generated. As shown in JP-B-39-9938, JP-B-39-13692, and JP-B-46-8745, the shape of the partition is variously modified, or JP-A-39-143 and JP-B-39-143. As shown in Japanese Patent Application Laid-Open No. 58-101263, a configuration has been proposed in which a collision with a partition portion is reduced by escaping a flow path on the outlet side in a tangential direction.

(Problems to be Solved by the Invention) However, the noise of the electric pump is generated mainly due to the spiral vortex in the radial direction generated by the impeller blades as well as the speed of collision with the partition portion. In the pump, such reduction of the spiral vortex is not taken into consideration, and the pump has a disadvantage that the noise reduction effect is poor.

(Means for Solving the Problems) The electric pump of the present invention has an impeller that is driven to rotate by a motor unit, and a pump casing that surrounds the impeller, and the pump casing is appropriately divided in a circumferential direction by a partition part. An inlet section and an outlet section provided at a distance,
An electric pump including a circumferential flow path from the inlet to the outlet surrounding the impeller provided on the outer peripheral portion of the impeller. An enlarged flow passage portion in the axial direction of the impeller is provided in a range from the upstream side to the outlet portion as appropriate.

(Operation) In the electric pump of the present invention, the flow path enlargement portion is provided in a range from the upstream side of the outlet portion to the outlet portion. The spiral vortex in the direction is reduced, and collides with the partition at a low speed and a small spiral vortex. In addition, the channel enlargement portion is provided in the axial direction of the impeller. For example, in a conventional electric pump, the channel can be formed by digging a channel groove of a pump casing forming the channel in the axial direction of the impeller. Does not affect the size and shape of the entire pump.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

In the electric pump 1 shown in FIG. 1, a motor cover 3 and a pump cover 4 are respectively caulked at the upper and lower ends of a hollow cylindrical casing 2.
A shaft 5a of an armature 5 disposed substantially at the center of the inside of the casing 2 is supported on the pump cover 4 at upper and lower ends via bearings 6,7. On the inner surface of the casing 2, a pair of magnets 8,
A brush 10 for supplying electricity to the commutator 9 of the armature 5 and an external connection terminal 11 are attached to the motor cover 3 via holders 12 and 13, respectively.

The armature 5, the magnets 8, 8, the commutator 9, the brush 10, and the external connection terminal 11 are a motor unit for driving a pump unit 14 provided below the armature 5.
Make up 15.

The pump section 14 includes a first impeller 16 and a second impeller 17 having the same configuration that are connected to the lower end of the shaft 5a of the armature 5 and driven to rotate, and a pump casing 18 surrounding these impellers 16 and 17. ing. Pump casing
Reference numeral 18 denotes the pump cover 4, a pump body 20 fixed to the pump cover 4 via a plurality of screws 19 (only one screw is shown), an annular first spacer 21, and an annular plate.
22 and an annular second spacer 23 (having the same configuration as the first spacer 21). Here, the plate 22 and the pump body 20 form an axial wall surrounding the first impeller 16, and the first spacer 21 forms a radial wall surrounding the first impeller 16, respectively. And plate
The reference numeral 22 denotes an axial wall surrounding the second impeller 17, and the second spacer 23 forms a radial wall surrounding the second impeller 17. Also, pump body 20 and plate
22 has an inlet hole 24 provided in the pump body 20 and a plate 22 at a portion of the outer periphery of the first impeller 16 facing the blade 16a.
Are provided with circumferential flow passage grooves 20a and 22a (see FIG. 2) between the first outlet holes 25 provided in the first and second outlet holes 25, respectively.
A first flow path 26 is formed by the inner peripheral surface of the spacer 21, and the first spacer 21 is provided between the inlet hole 24 and the first outlet hole 25 on the side where the first flow path 26 is not provided. As shown in FIG. 3, a partition portion 27 is provided to project inward in the radial direction to separate the spaces. On the other hand, the plate 22 and the pump cover 4 are provided with the first outlet hole 25 of the plate 22 and the pump cover 4 at a portion of the outer periphery of the second impeller 17 opposite to the blade 17a.
Channel grooves 22b and 4a (see FIG. 4) in the circumferential direction are respectively provided between the second passage hole 29 and the second outlet hole 28 provided in the second spacer hole 23, and the second passage 29 is formed by the inner peripheral surface of the second spacer 23. Has formed,
The second spacer 23 extends radially inward as shown in FIG. 5 to partition between the side where the second flow path 29 is not provided and the first outlet hole 25 and the second outlet hole 28. A partition 30 is provided.

Here, a portion facing the second outlet hole 28 of the flow channel groove 4a of the pump cover 4 forming the second flow channel 29 is a sectional view taken along the line VI-VI of FIG. VII line and VIII-VI
As shown in FIGS. 7 and 8, which are sectional views taken along the line II, a deep groove 31 in the axial direction of the second impeller 17 is provided, and this deep groove 31 is formed as shown in FIG. The outlet hole 28 is formed so as to be gradually inclined upward. (In FIG. 7 and FIG. 8, it is downward for reasons of illustration.) In addition to such a deep groove portion 31 reaching the second outlet hole 28 and being gradually inclined downward, FIG. As shown in FIG. 7, a stepped deep groove 31a having substantially the same cross-sectional shape in the circumferential direction may be used.

The motor cover 3 is provided with a discharge port 33 for guiding the fuel pumped into the casing 2 by the pump unit 14 through the check valve 32 to the outside.

In the electric pump 1 of the present embodiment, the motor unit 15 is energized from a battery (not shown) via the external connection terminal 11,
When the armature 5 is rotated, the pump
Fourteen first impeller 16 and second impeller 17 rotate. As a result, a fluid, for example, fuel in a fuel tank (not shown) is pumped into the pump casing 18 through the inlet hole 24, and the fuel is guided into the second flow passage 29 from the first outlet hole 25 through the first flow passage 26. Then, it enters the casing 2 through the second outlet hole 28, is discharged to the outside through the discharge port 33, and is supplied to an engine (not shown).

Here, the channel groove of the pump cover 4 forming the second channel 29
4a, the deep groove 31 is provided at the portion facing the second outlet hole 28, so that the flow path area is increased in this portion, so that the flow rate of the fluid such as fuel decreases due to the increase in volume, and at the same time, the radial direction increases. Of the spiral vortex decreases, and collides with the partition 30 at a low speed and with little spiral vortex. Therefore, noise in a high-frequency band determined by the number of impeller blades × impeller rotation speed is reduced.

The noise reduction effect will be described with reference to FIG. 10. The horizontal axis in FIG.
The flow path area at the boundary between the flow path 29 and the second exit hole 28 (S1
+ S2) and the flow area S1 (see FIG. 8) in the case where the deep groove 31 is not provided and the corresponding second area in the case where the deep groove 31 is provided.
The vertical axis indicates the ratio between the volume (V1 + V2) of the flow path 29 and the volume V1 (see FIG. 7) when the deep groove 31 is not provided. ○ indicates data of the sound pressure decrease amount, and Δ indicates data of the flow rate decrease rate.

As is clear from FIG. 10, the sound pressure is remarkable as the area ratio and the volume ratio increase, that is, as the flow area at the boundary between the deep groove 31 and the second outlet hole 28 increases and the volume of the deep groove 31 increases. Although the flow rate decreases, the decrease in the flow rate hardly occurs when the area ratio is 3 and the volume ratio is 2 to 3, and as a result, the deep groove portion 31 is designed so that the area ratio is 2 to 3 and the volume ratio is 1.5 to 3. Is preferred.

Even when the electric pump 1 designed with such an area ratio and a volume ratio is used, the result of measuring the sound pressure in the liquid is shown in FIG. 11 in comparison with the case of the conventional example, and the solid line is the present embodiment. The dashed line shows the case of the conventional electric pump 1 in the case of the electric pump 1 of the example. As shown in the figure, around the frequency 5.5KHz
It can be seen that there is a 3 dB drop in sound pressure (indicated by C in the figure).

The electric pump from which the above data was obtained is the first impeller 16 and the second impeller 17 having a diameter D = 35 mm (see FIG. 1), the height H of the first flow path 26 = the height H of the second flow path 29 H = 3.9m
m (see FIGS. 7 to 9), the width B of the first flow path 26 = the width B of the second flow path = 3.6 mm (see FIG. 8), and the area ratio is 3 and the volume ratio is 2 In the data shown in FIG.
When set to 5 mm and depth P = 7.8 mm (see Fig. 7),
The data of the area ratio 3 and the volume ratio 3 are obtained when the step-like deep groove 31a is similarly set to a length L = 8.5 mm and a depth P = 7.8 mm (see FIG. 9). .

Further, the electric pump 1 of the present embodiment has the same structure as the conventional electric pump except that the deep groove 31 is provided, and such a deep groove 31 forms a corresponding flow channel of the conventional type electric pump in the impeller axial direction. It can be formed by a simple process of digging into the hole, and the provision of such a deep groove portion 31 has no influence on the dimensions and shape of the entire electric pump. Therefore, an electric fuel pump having a noise prevention effect can be obtained with a simple structure, and at the same time, a conventional electric pump can be configured as an electric pump having a noise prevention effect by simple processing.

In the above embodiment, the deep groove portion 31 is provided only at the portion facing the second outlet hole 28 of the second flow path 29, but the similar deep groove portion is provided at the portion facing the first outlet hole 25 of the first flow channel 26. The shape of the deep groove portion 31 may be variously set, for example, not only the shape described in the above embodiment but also a curved bottom surface.

(Effect of the Invention) In the electric pump according to the present invention, since the fluid pumped into the pump casing collides with the partition at a low speed and a small spiral vortex, noise in a high frequency band determined by the number of impeller blades x the number of impeller rotations. Is reduced. In addition, the enlarged channel portion can be obtained by simple processing, and does not affect the dimensions and shape of the entire electric pump, so that an electric pump having a noise reduction effect can be configured easily and at low cost. It has the advantage that the pump can be easily diverted.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an electric pump, FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4, FIG. 4 is an enlarged view of a portion B of FIG. 1, FIG. 5 is a sectional view taken along line VV of FIG. 1, FIG. 6 is a sectional view taken along line VI-VI of FIG. 6 is a sectional view taken along the line VII-VII, FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 6, FIG. 9 is a sectional view similar to FIG. 7 showing another example of a deep groove portion, and FIG. The axis is the ratio of the flow path area at the boundary between the corresponding flow path portion and the outlet hole when the deep groove portion is provided to the flow path area when the deep groove portion is not provided, and the corresponding flow when the deep groove portion is provided. FIG. 11 is a diagram showing the relationship between the ratio of the volume of the road portion to the volume without the deep groove, the sound pressure reduction amount (dBA), and the flow rate reduction rate (%).
The figure is a diagram showing a frequency (KHz) -sound pressure (dBA) characteristic when sound pressure of the electric pump of the present embodiment is measured in a liquid, in comparison with a conventional electric pump. 1 ... Electric pump 4a, 20a, 22a.22b ... Channel groove 16 ... First impeller 17 ... Second impeller 16a, 17a ... Blade 18 ... Pump casing 24 ... Inlet hole 25 ... First Outlet holes 26,29 ... Flow path 28 ... Second outlet hole 31,31a ... Deep groove

Claims (1)

(57) [Claims] An impeller rotatably driven by a motor, and a pump casing surrounding the impeller;
The pump casing surrounds an inlet and an outlet provided at appropriate positions in the circumferential direction by a partition, and a blade provided on an outer peripheral portion of the impeller and extends from the inlet to the outlet. An electric pump comprising a circumferential flow path, wherein the flow path includes an axial flow path enlarged portion of the impeller in a range from an appropriate upstream side of the outlet portion to the outlet portion. An electric pump characterized by being provided.