JP2013241907A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain performance of a motor, in its turn, suction performance of a pump means, by cooling the motor.SOLUTION: A vacuum pump 1 includes a pump means 2 for compressing and discharging gas sucked in from a suction port 11b from an exhaust port 12b, and a motor 3 for driving this pump means. A housing 4 is arranged for storing a stator core 22 as a motor casing of the motor, a cooling passage Sc is formed between an outer surface of the stator core and an inner surface of the housing, and the motor is cooled by making the gas discharged from the exhaust port of the pump means flow to the cooling passage.

Description

  The present invention relates to a vacuum pump, and more particularly, to a vacuum pump including a pump unit that compresses gas sucked from a suction port and discharges it from an exhaust port, and a motor that drives the pump unit.

Conventionally, for example, a vacuum pump has been used to supply a negative pressure to a brake booster for an automobile, and as such a vacuum pump, a pump means for compressing the gas sucked from the suction port and discharging it from the exhaust port And a motor that drives the pump means is known (Patent Document 1).
In such a vacuum pump, the pump means is driven by the motor, thereby sucking gas from the suction port and supplying negative pressure to the booster, while discharging the sucked gas from the discharge port. It is like that.

Japanese Patent Laid-Open No. 4-187891

Here, since the brake vacuum pump is mounted in the engine room of the automobile, it is exposed to a high temperature environment depending on the temperature in the engine room and the temperature generated by the motor itself.
If the characteristics of the motor change due to the high temperature, the suction performance by the pump means also changes. Therefore, a stable negative pressure cannot be supplied, and the durability is affected.
For this reason, the conventional vacuum pump has a problem that a motor capable of operating even in a high temperature environment must be employed in the vacuum pump.
In view of such a problem, the present invention provides a vacuum pump that can cool a motor and maintain the performance of the motor, and hence the suction performance of the pump means.

That is, a vacuum pump according to the invention of claim 1 is a vacuum pump comprising a pump unit that compresses gas sucked from the suction port and discharges it from the exhaust port, and a motor that drives the pump unit.
A housing for housing the motor casing of the motor is provided, a cooling passage is formed between the outer surface of the motor casing and the inner surface of the housing, and the gas discharged from the exhaust port of the pump means is circulated through the cooling passage. The motor is cooled.

  According to the above invention, the gas discharged from the exhaust port flows through the cooling passage formed between the motor casing and the housing of the motor and cools the motor, whereby the performance of the motor, and hence the suction performance of the pump means. Can be maintained.

Sectional drawing of the vacuum pump concerning a present Example Sectional view of II-II part in FIG. Sectional view of III-III part in FIG.

Referring to the illustrated embodiment, FIG. 1 shows a vacuum pump 1 that supplies negative pressure to a brake booster, and is provided in an engine room of an automobile.
The vacuum pump 1 is composed of a pump means 2 that compresses and discharges the sucked gas, a motor 3 that drives the pump means 2, and a housing 4 that holds the motor 3. A so-called vane pump is used, and a brushless motor is used as the motor 3.

As shown in FIG. 2, the pump means 2 is provided on the upper surface of the pump casing 11, and a pump casing 11 having a substantially circular pump chamber 11 a formed on the upper surface and the motor 3 fixed on the lower surface. A cover 12 that closes the pump chamber 11a, a rotor 13 that rotates inside the pump chamber 11a by the motor 3, and a plurality of vanes 14 that divide the pump chamber 11a into a plurality of spaces as the rotor 13 rotates. The silencer 15 covers the upper surface of the cover 12.
The pump casing 11 is constituted by a substantially rectangular parallelepiped member. The pump chamber 11a formed on the upper surface of the pump casing 11 has a suction port 11b for sucking gas, and the cover 12 that closes the pump chamber 11a has An exhaust port 12a for discharging the compressed gas is formed.
As shown in FIG. 2, the suction port 11b communicates with the suction port 16 provided on the side surface of the pump casing 11, and the suction port 16 is connected to a booster through a pipe (not shown).
As shown in FIG. 1, the exhaust port 12a is formed in the cover 12 so as to discharge the compressed gas above the pump casing 11 and the cover 12, and as shown in FIG. 13 is formed on the substantially opposite side to the inlet 11b.

The center of the rotor 13 is provided at a position eccentric with respect to the center of the pump chamber 11a, and is connected to the drive shaft 21 of the motor 3 via a connecting member as shown in FIG. It is designed to rotate.
Further, the rotor 13 is formed with four slits 13a at equal intervals at an angle inclined with respect to the diameter direction, and the vanes 14 are provided in the slits 13a so as to be able to appear and disappear.
The vane 14 protrudes and retracts from the slit 13a so that its tip is brought into contact with the inner peripheral surface of the pump chamber 11a, thereby dividing the pump chamber 11a into a plurality of spaces.

The silencer 15 is a box-shaped member having a bottom and an opening at the lower end. The silencer 15 includes a flange 15a around the opening, and the flange 15a is in close contact with a seal member provided on the upper surface of the cover 12 of the pump casing 11. Thus, a damper space Sd partitioned from the outside is formed between the silencer 15 and the cover 12.
Further, as shown in FIG. 2, bolt holes 11c are drilled at the four corners of the pump casing 11, and bolts are passed through the bolt holes drilled at the same positions of the cover 12 and the silencer 15. The silencer 15 together with the cover 12 is fixed to the pump casing 11 by being inserted.
Further, the pump casing 11 and the cover 12 are formed with a through hole 17 penetrating from the upper surface to the lower surface, and the upper end of the through hole 17 opens into a damper space Sd formed by the silencer 15. Yes.
Therefore, the exhaust port 12a formed in the cover 12 and the through-hole 17 communicate with each other via the damper space Sd, and the gas discharged from the exhaust port 12a is the damper space Sd and the above-mentioned It passes through the through hole 17 and is discharged from the lower surface side of the pump casing 11.

The motor 3 is a so-called 4-pole 6-slot brushless motor, and includes a drive shaft 21 connected to the rotor 13 of the pump means 2, a stator core 22 having a cylindrical shape as a motor casing, and an interior of the stator core 22. 6 sets of coils 23 arranged so as to surround the drive shaft 21, and a substrate 24 provided outside the stator core 22 to control the coils 23.
The housing 4 constitutes a part of the motor 3 in this embodiment, and a first member 25 that is in close contact with the pump casing 11 and supports the front end side of the drive shaft 21, and the first member 25. A second member 26 that holds the stator core 22, a third member 27 that is provided below the second member 26 and supports the rear end side of the drive shaft 21, and the third member And a fourth member 28 which is provided on the lower surface of 27 and accommodates the substrate 24.
When the first member 25 to the third member 27 are combined, a space is formed in the interior thereof, and the fourth member 28 is a box-shaped member having a bottom and an open top surface. In addition, a space is formed between the third member 27 and the third member 27.
Bolt holes are formed at the same positions as the bolt holes 11c formed in the pump casing 11 at the four corners of the first to fourth members 25 to 28, and the motor 3 is formed on the lower surface of the pump means 2 by bolts. The first to fourth members 25 to 28 are fixed.

The drive shaft 21 includes a small-diameter portion 21a that protrudes up and down in FIG. 1 and a large-diameter portion 21b that is formed in accordance with the position of the coil 23, and the first and third members 25 of the housing 4 27 is provided with a bearing 29 that pivotally supports the small-diameter portion 21a, and four permanent magnets 30 arranged with different magnetic poles are fixed to the outer peripheral surface of the large-diameter portion 21b.
The stator core 22 has a cylindrical shape, and an upper end and a lower end thereof are sandwiched between a first member 25 and a third member 27 of the housing 4 as shown in FIG. Thus, the interior of the stator core 22, that is, the space in which the drive shaft 21 is provided is partitioned from the outside.
The stator core 22 has six projections 22a formed as a stator, and a slight gap is formed between the outer peripheral surface of the drive shaft 21 and the inner peripheral surface of the projection 22a.
The coils 23 are wound around the protrusions 22a, and the coils 23 are connected to the substrate 24 by wires (not shown). Under the control of the substrate 24, the coils 23 generate a magnetic field. Yes.

In the present embodiment, as shown in FIGS. 1 and 3, the center of the stator core 22 is slightly shifted to the left in the figure with respect to the housing 4, and only the right outer peripheral surface in the figure of the stator core 22 is the housing 4. The other parts exposed to the inside are held so that the second member 26 is in close contact so that the stator core 22 does not move.
The space formed between the outer surface of the stator core 22 and the inner surface of the housing 4 forms a first cooling passage Sc1 constituting the cooling passage Sc, and the pump means 2 as shown in FIGS. It communicates with a through hole 17 formed in the pump casing 11.
A communication port 31 indicated by a broken line is formed in the bottom surface of the second member 26 and the third member 27 in the housing 4, and the cooling passage formed by the third member 27 and the fourth member 28. It communicates with the second cooling passage Sc2 constituting the Sc.
The communication port 31 is formed below the communication position of the upper through hole 17 shown in the drawing, and the communication port 31 is provided on the substantially opposite side of the through hole 17 in the first cooling passage Sc1. The gas flowing through the inside of the first cooling passage Sc1 flows along the outer surface of the stator core 22.
As shown in FIG. 1, the fourth member 28 is formed with a discharge port 28a on the side surface, whereby the gas flowing through the second cooling passage Sc2 is discharged from the discharge port 28a. .
In the vacuum pump 1 according to the present embodiment, the diameter of the exhaust port 12a formed in the pump means 2 is larger than that of the other through hole 17 and the communication port 31 and the discharge port 28a formed in the housing 4. Also has a small diameter.

The operation of the vacuum pump 1 having the above configuration will be described. When a current is applied to the coil 23 via the substrate 24 constituting the motor 3, a magnetic field is generated in the coil 23 and the drive shaft 21 is provided. The permanent magnets 30 approach or separate from each other, whereby the drive shaft 21 rotates.
In the pump means 2, the rotor 13 connected to the drive shaft 21 rotates counterclockwise in FIG. 1 in a pump chamber 11 a formed in the pump casing 11, whereby the vane 14 divides the pump chamber 11 a into a plurality of spaces. It moves in the state where it was divided into.
As the rotor 13 rotates, when the space defined by the vanes 14 passes through the suction port 11b formed in the pump chamber 11a, the volume of the space gradually increases with the rotation of the rotor 13 thereafter. Therefore, gas is sucked from the suction port 11b, and negative pressure is supplied to the booster through the suction port 16.
Thereafter, since the volume of the space partitioned by the vane 14 is further reduced toward the exhaust port 12a, the compressed gas is discharged from the discharge port 28a when the space communicates with the exhaust port 12a. It has become.

The gas discharged from the discharge port 28a flows into the damper space Sd formed by the silencer 15, whereby the noise generated by the vacuum pump 1 is reduced.
The gas flowing through the damper space Sd flows through the through hole 17 formed in the pump casing 11 and the cover 17 and then flows into the first cooling passage Sc1 among the cooling passages Sc formed in the housing 4.
At this time, since the diameter of the exhaust port 12a is smaller than the diameter of the through hole 17, the gas in the damper space Sd flows into the through hole 17 as compared with the exhaust resistance at the exhaust port 12a. The exhaust resistance at that time is small, so that the intake performance of the pump means 2 is not deteriorated.

Here, the coil 23 of the motor 3 generates heat by a current that is constantly applied, and the temperature of the stator core 22 on which the protrusion 22a around which the coil 23 is wound is increased due to heat transfer.
The gas flowing into the first cooling passage Sc1 from the through hole 17 flows toward the communication port 31 formed in the third member 27, and the gas flows along the surface of the stator core 22 at that time. The stator core 22 and the coil 23 held inside the stator core 22 are cooled.
The gas flowing through the first cooling passage Sc1 is discharged to the second cooling passage Sc2 through the communication port 31, and the diameter of the exhaust port 12a is smaller than the diameter of the communication port 31 at this time as well. Therefore, the exhaust resistance when the gas in the first cooling passage Sc1 flows into the communication port 31 is smaller than the exhaust resistance at the exhaust port 12a.
Since the substrate 24 is disposed in front of the communication port 31 in the second cooling passage Sc2, the gas flowing in from the communication port 31 is directly blown onto the substrate 24, so that the substrate 24 is efficiently It is designed to be cooled.
Thereafter, the gas is discharged from the discharge port 28a formed in the fourth member 28 and spaced from the communication port 31, and the diameter of the exhaust port 12a is smaller than that of the discharge port 28a. Therefore, the exhaust resistance when the gas in the first cooling passage Sc1 is discharged from the discharge port 28a is smaller than the exhaust resistance of the exhaust port 12a.

Thus, according to the vacuum pump 1 in the present embodiment, the cooling passage Sc formed between the outer surface of the stator core 22 of the motor 3 and the inner surface of the housing 5 is discharged from the exhaust port 12a of the pump means 2. By circulating the generated gas, the motor 3 can be cooled by the gas.
For this reason, even if the motor 3 having lower heat resistance than the conventional one is used, the vacuum pump 1 can be operated without impairing the stability, and the vacuum pump 1 can be obtained at low cost.
In this embodiment, the brushless motor 3 is used as the motor 3. However, since the brushless motor 3 includes the coil 23 that generates heat at a position close to the inner peripheral surface of the stator core 22, the coil that generates heat. 23 can be efficiently cooled.
At this time, since the gas does not flow into the space on the drive shaft 21 side in the stator core 22, foreign matter does not enter the rotating portion of the drive shaft 21 inside the stator core 22, and the occurrence of abnormality of the motor 22 due to the foreign matter is prevented. Can do.
Further, the brushless motor 3 requires a substrate 24. The substrate 24 is also provided in the cooling passage Sc and cooled by the gas, and the heat resistance of the substrate 24, which is a problem of the brushless motor 3, is also eliminated. can do.
In this embodiment, the cooling passage Sc is provided with a first cooling passage Sc1 for cooling the stator core 22 and a second cooling passage Sc2 for cooling the substrate 24. Two cooling passages Sc2 can be separately cooled.
Further, by providing the pump means 2 with a silencer 15 that forms a damper space Sd, it is possible to reduce the noise accompanying the discharge of the gas, and by forming the through hole 17 in the pump casing 11, Gas can be supplied to the cooling passage Sc without providing new piping.
At this time, since the diameter of the discharge port 28a is smaller than the diameter of the through hole 17, the exhaust resistance when flowing into the through hole 17 is larger than the exhaust resistance of the gas discharged from the discharge port 28a. It is small and the efficiency of the pump means 2 due to the gas flowing through the through hole 17 is not lowered.

In the above embodiment, as shown in FIG. 3, only a part of the stator core 22 is exposed to the cooling passage Sc. However, by making the shape of the housing 5 different, the entire circumference of the stator core 22 is surrounded. A cooling passage may be formed.
Further, in FIG. 1 of the above-described embodiment, a groove is formed in the circumferential direction so as to communicate with the cooling passage Sc at the contact portion of the second member 26 with the stator core 22, and this groove is also gas as the cooling passage Sc. Can also be distributed.
Further, the fourth member 28 constituting the housing 4 is provided between the first member 25 and the pump casing 11, and the substrate 24 is placed inside the fourth member 28 in the same manner as in the embodiment. It is good also as a structure to accommodate.
In this case, the gas passes through the communication hole 31 formed between the first member 25 and the fourth member 28 after the through-hole 17 flows into the second cooling passage Sc2 formed in the fourth member 28, for example. The stator core 22 can be cooled by flowing into the first cooling passage Sc1.
On the other hand, in the above embodiment, gas is allowed to flow into the fourth member 28 in the housing 5 to cool the substrate, but the communication port 31 is omitted and a discharge port is formed in the second member 26. It is also possible to cool only the stator core 22 and not the substrate 24.
And the said motor 3 in the said Example is good also as what is called a brush motor, and even if it is a brush motor, it can anticipate cooling the motor 3 whole by cooling the motor casing exposed inside the housing.

DESCRIPTION OF SYMBOLS 1 Vacuum pump 2 Pump means 3 Motor 4 Housing 11 Pump casing 11a Pump chamber 11b Suction port 12 Cover 12a Exhaust port 15 Silencer 21 Drive shaft 22 Stator core (motor casing)
Sd Damper space Sc Cooling passage Sc1 First cooling passage Sc2 Second cooling passage

Claims (4)

In a vacuum pump comprising pump means for compressing the gas sucked from the suction port and discharging it from the exhaust port, and a motor for driving the pump means,
A housing for housing the motor casing of the motor is provided, a cooling passage is formed between the outer surface of the motor casing and the inner surface of the housing, and the gas discharged from the exhaust port of the pump means is circulated through the cooling passage. Vacuum pump characterized by cooling the motor. The motor is a brushless motor, and includes a plurality of sets including a drive shaft including a permanent magnet and connected to the pump means, and a stator core serving as the motor casing and surrounding the drive shaft. A coil and a substrate that is provided outside the stator core and controls the coil;
The vacuum pump according to claim 1, wherein the substrate is disposed inside the cooling passage. The cooling passage includes a first cooling passage formed between an inner surface of the housing and an outer surface of the stator core, a second cooling passage that is partitioned with respect to the first cooling passage and accommodates the substrate, and A communication port that communicates the first cooling passage with the second cooling passage;
The vacuum pump according to claim 2, wherein the diameter of the exhaust port in the pump means is smaller than the diameter of the communication port. The pump means includes a pump casing in which a substantially circular pump chamber is formed on one end surface and the motor is fixed to the other end surface, and a pump casing formed on one end surface of the pump casing to close the pump chamber. And a cover formed with the exhaust port, a rotor that is rotated inside the pump chamber by the motor, and a vane that divides the pump chamber into a plurality of spaces as the rotor rotates,
Forming a through hole penetrating from one end surface to the other end surface of the pump casing, and further providing the through hole in communication with a cooling passage formed in the housing;
Furthermore, a silencer is provided on the one end face side of the pump casing to form a damper space for communicating the exhaust port and the through hole.
The vacuum pump according to any one of claims 1 to 3, wherein the air discharged from the exhaust port flows into the cooling passage through the damper space and the through hole.

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