JP2002180975A - Electric gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that, if the polarity of a motor is connected erroneously in an electric gear pump, it may cause failure in oil seal. SOLUTION: This electric gear pump has a shaft 6 served as the both of a rotary shaft 4 of an electric motor 2 and a rotary shaft 5 of a pump 3. A connecting part 6d of the shaft 6 is inserted into a connecting hole of a driving gear 13 of the pump 3 as a support shaft. The connecting part 6d and the driving gear 13 are connected to each other by a one-way clutch 42 allowing only the transmission of the normal rotation of the motor 2. A simple structure, for example, an X ring is used as an oil seal 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric gear pump driven by a motor.

[0002]

2. Description of the Related Art In recent years, the demand for energy saving in automobiles has become remarkable, and so-called hybrid cars using both an engine and an electric motor as drive sources have appeared. With the flow of such technology, a gear pump that generates hydraulic pressure for driving auxiliary equipment has been electrified to obtain the required output when needed, and to suppress or stop the output when not needed. It is considered to save energy.

[0003] Generally, in this type of electric gear pump, a drive gear and a driven gear that mesh with each other are incorporated in an oval cavity formed in a housing. The drive gear and its support shaft are integrated, and the driven gear and its support shaft are integrated. On the other hand, between the support shaft of the drive gear and the motor shaft of the electric motor, the drive transmission is connected using a joint such as an Oldham joint. That is, regardless of whether the motor shaft rotates forward or backward, the rotation is transmitted to the drive gear via the joint and the support shaft, and the motor shaft and the drive gear are rotated integrally.

[0004]

However, the following disadvantages are associated with the adoption of such a configuration in which the motor rotates integrally in the forward and reverse directions. That is, the power supply wiring of the electric motor may be made with the wrong polarity, in which case,
The gear pump rotates in the opposite direction to the normal rotation direction. Then, since the high pressure region and the low pressure region partitioned from each other inside the gear pump are reversed, an abnormal load is applied to the oil seal partitioning the inside and the outside of the gear pump, so that the function of the oil seal is hindered. There is a risk.

Therefore, a large-sized oil seal having a complicated structure capable of withstanding the abnormal load as described above must be used. As a result, the size of the electric gear pump increases and the manufacturing cost increases. . Also, there is a case where the electric pump and another pump are connected in parallel and another pump is used while the electric pump is stopped.
Oil pumped from another pump may flow in from the discharge port of the electric pump and reverse the driving gear and the driven gear in the electric pump. Therefore, in order to prevent this, a backflow prevention device is required at the discharge port of the electric pump, which tends to increase the size of the device. On the other hand, in this type of electric gear pump, there is a strong demand for miniaturization and cost reduction.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electric pump unit that is small and inexpensive, and that can prevent problems when the motor rotates in reverse and when the parallel pump is driven. It is to be.

[0007]

To achieve the above object, the present invention provides an electric gear pump having a driving gear and a driven gear that mesh with each other, the driving gear being driven by a motor via a support shaft thereof. In the above, the support shaft is inserted into a center hole of the drive gear, and a one-way clutch that allows transmission of only the forward rotation of the motor is interposed between the center hole of the drive gear and the support shaft. Is what you do.

In the present invention, the one-way clutch does not transmit the reverse rotation to the drive gear even if the power supply wiring of the motor is made in the wrong polarity and the support shaft is rotated reversely.
The support shaft idles in the center hole of the drive gear. Therefore, since the driving gear does not reversely rotate, the reversal between the high pressure region and the low pressure region in the gear pump can be prevented, and as a result, an abnormal load is not applied to the oil seal partitioning the inside and outside of the gear pump. As a result, it is possible to use, for example, a small and simple structure having an X-shaped cross section as the oil seal. This makes it possible to provide a small and inexpensive electric gear pump.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic sectional view showing the internal configuration of the electric gear pump according to one embodiment of the present invention. Referring to FIG. 1, the electric gear pump 1 is configured as an integrated unit by combining an electric motor 2 and a pump 3, and a rotating shaft 4 of the electric motor 2 and a rotating shaft 5 of the pump share a common shaft 6. It consists of.

The electric motor 2 has a motor housing 7. The motor housing 7 has a first housing 8 formed of a bottomed cylinder that concentrically surrounds the rotating shaft 4, and an end wall that closes an open portion of the first housing 8. 9 is included. Although not shown, a rotor integrally rotating with the rotating shaft 4 and a stator supported by the first housing 8 and surrounding the rotor are arranged in the motor housing 7. On the other hand, the pump 3 includes a pump housing 10. The pump housing 10 includes a second housing 11 formed of a bottomed cylinder and the end wall 9. 31 is the second
A screw for fixing the housing 11 to the end wall 9.

A drive gear 13 and a driven gear 14 as a rotor meshing with each other are housed in a cavity 12 having an oval cross section defined in the pump housing 10, and the side surfaces 13a and 14a of these gears 13 and 14 are in contact with each other. Between the end wall 9, a side plate 15 made of, for example, an aluminum alloy is fitted. Side plate 15
Are formed with an insertion hole 16 that penetrates a later-described intermediate diameter portion 6b of the shaft 6, and a support hole 18 that rotatably supports a support shaft 17 of the driven gear 14. The support shaft 17 is driven gear 14
Is formed integrally or separately. As a separate coupling method, for example, a structure in which coupling is performed using splines, serrations, keys, deformed cross sections, or the like, or a method in which a shaft is fixed and a driven gear is rotatably supported is used. As an example of the latter, the driven gear is rotatably supported by being inserted into a shaft in a state where a bearing is attached to a hollow inner diameter portion of the driven gear. In the end wall portion 11a of the second housing 11, support holes 21 for supporting a shaft end 6e of the shaft 6 and a support shaft 17, which will be described later, via corresponding slide bearings 19 and 20, respectively.
22 are formed.

Between the back surface 15b of the gear side surface 15a of the side plate 15 and the surface 9a of the end wall 9 opposed thereto, a substantially three-shaped seal 30 as a side seal is provided.
The seal 30 partitions the inside of the cavity 12 into a high-pressure area H and a low-pressure area L (see FIG. 4). The shaft 6 has a large-diameter portion 6a rotatably supported by the motor housing 7 via first and second rolling bearings 24 and 25, and an end wall 9 connected to the large-diameter portion 6a.
A middle diameter portion 6b penetrating through the insertion hole 26 into the pump housing 10, and a constricted portion 6c continuous with the middle diameter portion 6b.
A small-diameter connecting portion 6d as a support shaft for the rotary shaft 5 of the pump and the driving gear 13, and a shaft end portion 6 continuous with the connecting portion 6d.
e in sequence.

Referring to FIGS. 2 and 5, a one-way clutch 42 is provided between an outer peripheral surface of connecting portion 6d as a support shaft and an inner peripheral surface of connecting hole 38 as a center hole of drive gear 13. Is interposed. The one-way clutch 42 connects the connecting portion 6d and the drive gear 13 so as to be integrally rotatable only when the connecting portion 6d of the rotating shaft 5 included in the shaft 6 is normally rotated by the motor 2. The structure of the one-way clutch 42 includes, for example, the inner peripheral surface 4 of the connection hole 38 of the drive gear 13.
3, a wedge-shaped housing recess 4 that narrows in the forward rotation direction of the motor 2 (the direction indicated by the white arrow in FIG. 5).
4, there is a structure in which the cylindrical roller 45 is accommodated in the accommodation concave portion 44 and an urging member 46 for urging the cylindrical roller 45 toward the narrow side of the accommodation concave portion 44 is provided. The bottom of the accommodation recess 44 serves as a cam surface 47 for pressing the cylindrical roller 45 against the outer peripheral surface of the connecting portion 6d.

At the time of forward rotation of the motor, the cylindrical roller 45 moves to the narrow side of the wedge-shaped receiving recess 44, and is strongly clamped between the cam surface 47 and the outer peripheral surface of the connecting portion 6d.
d to the drive gear 13. On the other hand, when the motor rotates in the reverse direction, the cylindrical rollers 45 move toward the wide side of the wedge-shaped accommodation recess 44, so that the holding of the cylindrical rollers 45 is released. As a result, the connecting portion 6d idles in the connecting hole 38. The first rolling bearing 24 is held by a holding portion 32 formed on the end wall 8a of the first housing 8. Insertion hole 26 in end wall 9
Has a large diameter portion 27, a middle diameter portion 28, and a small diameter portion 29 in this order. The large diameter portion 27 holds the second rolling bearing 25. Medium diameter portion 28 of insertion hole 26 and medium diameter portion 6b of shaft 6
An oil seal 23 that seals between them is interposed between the two. A gap is provided between the small diameter portion 29 of the insertion hole 26 and the middle diameter portion 6b of the shaft 6.

Next, in FIG. 2, which is a cross-sectional view taken along the line II-II of FIG. 1, the directions of rotation of the drive gear 13 and the driven gear 14 interlocked therewith are indicated by arrows.
A suction chamber 33 is formed on the rotation direction side and a discharge chamber 34 is formed on the opposite rotation direction side on both sides of the meshing positions of 3, 3. These suction chambers 33
The discharge chamber 34 is connected to a suction destination and a discharge destination (not shown) outside the pump housing 10 via a suction port 35 and a discharge port 36 that open at corresponding positions of the first housing 11. In FIG. 2, hatching of the cross section is partially omitted.

Next, in FIG. 3, which is a sectional view taken along the line III--III in FIG. 1, a relief groove extending from the meshing position of the two gears 13 and 14 to the suction chamber 33 side is formed on the gear side surface 15a of the side plate 15. 63 and a relief groove 64 extending toward the discharge chamber 36 are formed. These escape grooves 63,
Numeral 64 is for preventing the occurrence of so-called confinement in which fluid is confined in a closed area formed by the side plate 15 and each meshing gear tooth at the meshing position of the two gears 13 and 14. 65 is an insertion hole 16 and a support hole 18
And the suction chamber 33 communicate with each other.

On the other hand, in FIG.
The seal 30 is accommodated in a substantially groove-shaped accommodation groove 37 on the back surface (non-gear-side surface) 15b of the side plate 15 and the side plate 15 and the end wall 9 facing each other with the seal 30 as a boundary. Is partitioned into a low-pressure area L communicating with the suction chamber 33 side and a high-pressure area H communicating with the discharge chamber 34 side. In the rear surface 15b, the insertion hole 16 and the support hole 18 and the suction chamber 33 in the low pressure region L are provided.
A pair of communication grooves 66 are formed to communicate with the sides.

According to the present embodiment, even if the power supply wiring of the electric motor 2 is made in the wrong polarity, and the connecting portion 6d as the support shaft is rotated in the reverse direction, the one-way clutch 42 works. The connecting portion 6d idles in the connecting hole 38. Therefore, reversal of the high pressure region and the low pressure region in the pump can be prevented, and no abnormal load is applied to the oil seal 23 that partitions the inside and outside of the pump. As a result, it is possible to use, for example, a small and simple structure having an X-shaped cross section as the oil seal 23. This makes it possible to provide a small and inexpensive electric gear pump.

The present invention is not limited to the above-described embodiment. For example, another known configuration using a sprag or the like as the one-way clutch may be used. Also,
Side plates may be used on both sides of a pair of gears,
Further, the side plate may be abolished at all. Alternatively, the support shaft and the motor shaft may be formed separately and connected to each other by, for example, an Oldham coupling or another coupling.
In addition, various changes can be made within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electric gear pump according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, with hatching partially omitted.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view of a one-way clutch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric gear pump 2 Electric motor 3 Pump 4, 5 Rotating shaft 6 Shaft 6d Connection part (rotating shaft, support shaft) 12 Cavity 13 Drive gear 14 Follower gear 15 Side plate 23 Oil seal 30 Seal of approximately 3 shape (side seal) ) 38 connecting hole 42 one-way clutch 44 accommodation recess 45 cylindrical roller 46 urging member 47 cam surface L low pressure area H high pressure area

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H041 AA02 BB02 CC19 DD01 DD07 DD10 DD21 3H044 AA02 BB02 CC18 DD01 DD06 DD09 DD18 DD19

Claims (1)

[Claims] An electric gear pump having a driving gear and a driven gear that mesh with each other, wherein the driving gear is driven by a motor via a supporting shaft, wherein the supporting shaft is inserted into a center hole of the driving gear, and An electric gear pump comprising a one-way clutch interposed between a center hole and a spindle to allow transmission of only forward rotation of a motor.