CN115247633B

CN115247633B - Parallel pump

Info

Publication number: CN115247633B
Application number: CN202210422880.6A
Authority: CN
Inventors: 白井敦士; 佐藤崇明; 三马拓实
Original assignee: Kawasaki Jukogyo KK
Current assignee: Kawasaki Motors Ltd
Priority date: 2021-04-26
Filing date: 2022-04-21
Publication date: 2024-03-08
Anticipated expiration: 2042-04-21
Also published as: JP2022168418A; CN115247633A

Abstract

The parallel pump includes: a drive shaft to which a drive gear (6) is fixed; a driven shaft to which a driven gear (7) is fixed; and a gear chamber which accommodates the driving gear (6) and the driven gear (7) and stores oil. A groove (8) extending along the meshing area of the drive gear (6) and the driven gear (7) is formed on at least one of a pair of opposing surfaces of the gear chamber, which face each other through the drive gear (6) and the driven gear (7). The ends of the groove (8) on the rotation direction side of the driving gear (6) and the driven gear (7) are bifurcated along the rotation direction of the driving gear (6) and the driven gear (7).

Description

Parallel pump

Technical Field

The present invention relates to a parallel pump including a pair of piston pump mechanisms arranged in parallel with each other.

Background

Conventionally, a parallel pump including a pair of piston pump mechanisms arranged in parallel with each other has been known. For example, japanese patent application laid-open No. 2000-220566 discloses a parallel pump 100 as shown in fig. 5.

Specifically, in the parallel pump 100, the first piston pump mechanism 120 and the second piston pump mechanism 130 are arranged in parallel with each other in the housing 110. A pump chamber 111 accommodating the first and second piston pump mechanisms 120 and 130 is formed in the housing 110.

The first piston pump mechanism 120 is driven by a drive shaft 140 and the second piston pump mechanism 130 is driven by a driven shaft 150. One end of the drive shaft 140 is located outside the housing 110 and is coupled to a prime mover such as an engine or an electric motor.

A drive gear 160 is fixed to the drive shaft 140 between the one end and the first piston pump mechanism 120. A driven gear 170 engaged with the driving gear 160 is fixed to the driven shaft 150. A gear chamber 112 accommodating a driving gear 160 and a driven gear 170 is also formed in the housing 110.

In the parallel pump 100 of japanese patent application laid-open No. 2000-220566, the first piston pump mechanism 120 and the second piston pump mechanism 130 are variable capacity type of swash plate pump type. In each of the first piston pump mechanism 120 and the second piston pump mechanism 130, a part of the working oil is supplied between the shoe plate fixed to the swash plate and the shoe to be used as lubricating oil. The oil is stored in the pump chamber 111.

The oil stored in the pump chamber 111 is also supplied to the gear chamber 112, and is also stored in the gear chamber 112. Accordingly, in the gear chamber 112, the oil is stirred by the rotation of the driving gear 160 and the driven gear 170. In more detail, around the driving gear 160, oil flows in a rotation direction of the driving gear 160, and around the driven gear 170, oil flows in a rotation direction of the driven gear 170.

Further, in the parallel pump 100 of japanese patent application laid-open No. 2000-220566, linear grooves 180 (linear in fig. 5, orthogonal to the paper surface) extending along the meshing area of the drive gear 160 and the driven gear 170 are formed in the pair of opposing surfaces 113 and 114 of the gear chamber 112, which face each other with the drive gear 160 and the driven gear 170 interposed therebetween.

Disclosure of Invention

In the first half of the step of meshing the drive gear 160 and the driven gear 170, the teeth of the other gear enter the tooth space (tooth space) of the one gear, and the volume of the tooth space is reduced. Therefore, the oil in the tooth grooves overflows in the axial direction of the gear. In contrast, if the grooves 180 are present as described above, the oil overflowed from the tooth grooves flows into the grooves 180. Therefore, the compression work (so-called stirring loss) of the gears to compress the oil is reduced. On the other hand, in the latter half of the meshing process of the driving gear 160 and the driven gear 170, the tooth space increases in volume by pulling out the tooth of one gear from the tooth space of the other gear. Thus, oil is immersed from the grooves 180 into the tooth slots.

In this way, in the parallel pump 100 of japanese patent application laid-open No. 2000-220566, since the compression work of the gears is reduced, the efficiency of the parallel pump 100 (the ratio of the work performed with respect to the pump applying work from the prime mover) is improved. However, for parallel pumps, further efficiency improvements are desired.

Accordingly, an object of the present invention is to provide a parallel pump capable of improving efficiency as compared with the conventional pump.

As a result of intensive studies to solve the above-described problems, the inventors of the present invention have found that, when a linear groove is formed in at least one of a pair of opposing surfaces of a gear chamber facing each other through a driving gear and a driven gear as in the prior art, oil flows only linearly along the groove shape in the groove, and therefore, it is necessary to accelerate the oil that has entered a tooth space in the circumferential direction of the gear in the latter half of the meshing process. The present invention has been completed from such a viewpoint.

That is, the parallel pump of the present invention is characterized by comprising: a drive shaft to which a drive gear is fixed; a driven shaft to which a driven gear meshed with the drive gear is fixed; and a gear chamber that accommodates the drive gear and the driven gear and stores oil, wherein a groove that extends along a meshing area between the drive gear and the driven gear is formed in at least one of a pair of opposing surfaces of the gear chamber that face each other with the drive gear and the driven gear interposed therebetween, and an end portion of the groove on a side of a rotation direction of the drive gear and the driven gear is bifurcated along the rotation direction of the drive gear and the driven gear.

According to the above configuration, the end portions on the rotation direction side of the driving gear and the driven gear formed in the grooves of the facing surfaces of the gear chamber are bifurcated along the rotation direction of the driving gear and the driven gear, and therefore the flow of oil in the grooves is also bifurcated. Therefore, in the latter half of the engagement process, oil having a circumferential velocity can be made to infiltrate from the grooves into the tooth grooves. This can reduce acceleration work and can improve the efficiency of the parallel pump as compared with the conventional pump.

According to the present invention, a parallel pump capable of improving efficiency as compared with the conventional pump is provided.

Drawings

FIG. 1 is a cross-sectional view of a parallel pump according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1;

FIG. 3 is a perspective view of a portion of the housing body;

fig. 4 is an enlarged view of the meshing area of the drive gear and the driven gear;

fig. 5 is a cross-sectional view of a conventional parallel pump.

Detailed Description

Fig. 1 shows a parallel pump 1 according to an embodiment of the invention. The parallel pump 1 includes a housing 2, and a first piston pump mechanism 3A and a second piston pump mechanism 3B arranged in parallel with each other in the housing 2. For example, the arrangement direction of the first piston pump mechanism 3A and the second piston pump mechanism 3B is a horizontal direction.

The first piston pump mechanism 3A is driven by a drive shaft 4 and the second piston pump mechanism 3B is driven by a driven shaft 5. The drive shaft 4 and the driven shaft 5 are parallel to each other. Hereinafter, for convenience of explanation, one of the drive shaft 4 and the driven shaft 5 in the axial direction (left side in fig. 1) is referred to as a front side, and the other (right side in fig. 1) is referred to as a rear side.

The housing 2 includes a housing main body 22, and a front cover 21 and a rear cover 23 attached to the housing main body 22. The case main body 22 includes a cylindrical peripheral wall 24 extending in the front-rear direction and a partition wall 25 provided at a front position within the peripheral wall 24. The front cover 21 covers a front side space facing the front surface of the partition wall 25, and the rear cover 23 covers a rear side space facing the rear surface of the partition wall 25.

A pump chamber 11 is formed between the partition wall 25 and the rear cover 23, and a gear chamber 12 is formed between the partition wall 25 and the front cover 21. The first piston pump mechanism 3A and the second piston pump mechanism 3B are accommodated in the pump chamber 11.

The drive shaft 4 and the driven shaft 5 each penetrate the partition wall 25. The drive shaft 4 also penetrates the front cover 21. One end of the drive shaft 4 located outside the housing 2 is coupled to a prime mover such as an engine or an electric motor. At least one of the drive shaft 4 and the driven shaft 5 may penetrate the rear cover 23.

The drive shaft 4 is rotatably supported by a bearing 41 held by the partition wall 25 and a bearing 42 held by the rear cover 23. The driven shaft 5 is rotatably supported by a bearing 51 held by the partition wall 25 and a bearing 52 held by the rear cover 23.

In the present embodiment, the first piston pump mechanism 3A and the second piston pump mechanism 3B are of a swash plate pump type variable capacity type. The first piston pump mechanism 3A and the second piston pump mechanism 3B have the same configuration as each other. Hereinafter, a structure of the first piston pump mechanism 3A will be described as a representative.

However, the first piston pump mechanism 3A and the second piston pump mechanism 3B may be of a variable displacement type of a tilt-axis pump type. Alternatively, the first piston pump mechanism 3A and the second piston pump mechanism 3B may be fixed capacity type.

The first piston pump mechanism 3A includes a valve plate 31, a cylinder block 32, a plurality of pistons 33, a swash plate 36, and a support table 37. The valve plate 31 is mounted to the rear cover 23. Although not shown, the valve plate 31 is provided with an arc-shaped suction port and discharge port, and the rear cover 23 is provided with a suction path communicating with the suction port and a discharge path communicating with the discharge port.

The cylinder block 32 is fixed to the drive shaft 4, and slides with the valve plate 31 by rotating together with the drive shaft 4. The cylinder block 32 is provided with a plurality of cylinder bores opening in a direction opposite to the valve plate 31 around the drive shaft 4. The pistons 33 are inserted into the cylinder bores, respectively. Although not shown, a cylinder port is provided in the cylinder block 32 from the bottom of each cylinder bore to the valve plate 31.

A shoe 34 is attached to the head of each piston 33. In the present embodiment, the shoe 34 slides on an annular shoe plate 35 fixed to the swash plate 36. However, the shoe plate 35 may be omitted and the shoe 34 may be slid on the swash plate 36. The shoe 34 is pressed by a pressing member, not shown, to maintain a contact state with the shoe plate 35.

Although not shown, an oil passage is formed in the piston 33 and the shoe 34 from the rear end surface of the piston 33 to the shoe plate 35. Therefore, a part of the hydraulic oil sucked into the cylinder bore through the suction port and the cylinder port is supplied between the shoe plate 35 and the shoe 34, and is used as the lubricating oil. The oil is stored in the pump chamber 11.

The swash plate 36 is supported by a support base 37 attached to the partition wall 25 from the opposite side to the pistons 33. The swash plate 36 is swingably supported on a support table 37 about a swing axis extending in the arrangement direction of the first piston pump mechanism 3A and the second piston pump mechanism 3B.

The driving gear 6 and the driven gear 7 which are engaged with each other are accommodated in the gear chamber 12. The driving gear 6 is fixed to the driving shaft 4, and the driven gear 7 is fixed to the driven shaft 5. The tooth profile shape (number of teeth, pitch of teeth, depth of teeth, etc.) of the driving gear 6 is the same as the tooth profile shape of the driven gear 7.

The oil stored in the pump chamber 11 is also supplied to the gear chamber 12 via through holes, not shown, provided in the partition wall 25 and the bearings 41 and 51, and is also stored in the gear chamber 12. Accordingly, in the gear chamber 12, the oil is stirred as the driving gear 6 and the driven gear 7 rotate. More specifically, around the drive gear 6, the oil flows in the rotation direction of the drive gear 6, and around the driven gear 7, the oil flows in the rotation direction of the driven gear 7.

The gear chamber 12 has a pair of opposed faces 13, 14 opposed to each other via the drive gear 6 and the driven gear 7. The facing surface 13 is a rear surface of the front cover 21, and the facing surface 14 is a front surface of the partition wall 25. In addition, the gear chamber 12 has a peripheral surface 15 surrounding the driving gear 6 and the driven gear 7.

As shown in fig. 2, the peripheral surface 15 has a first cylindrical surface 15a having a diameter slightly larger than the tip circle 61 (see fig. 4) of the drive gear 6 and a second cylindrical surface 15b having a diameter slightly larger than the tip circle 71 (see fig. 4) of the driven gear 7. That is, the peripheral surface 15 protrudes between the driving gear 6 and the driven gear 7 toward the meshing area thereof. Here, as shown in fig. 4, the "meshing area" refers to an area surrounded by the addendum circle 61 of the drive gear 6 and the addendum circle 71 of the driven gear 7 (a biconvex-lens-shaped area between the upstream-side intersection point a and the downstream-side intersection point B of the addendum circles 61, 71).

In the present embodiment, as shown in fig. 1 and 3, grooves 8 extending along the meshing area of the drive gear 6 and the driven gear 7 are formed in the facing surfaces 13 and 14 of the gear chamber 12, respectively.

The grooves 8 are Y-shaped, and the ends of the grooves 8 on the rotation direction side of the driving gear 6 and the driven gear 7 are bifurcated in the rotation direction of the driving gear 6 and the driven gear 7. More specifically, as shown in fig. 4, each groove 8 includes a straight line portion 81, a first branch portion 82, and a second branch portion 83.

The linear portion 81 extends in a direction orthogonal to the arrangement direction of the driving gear 6 and the driven gear 7 (a direction connecting the central axis 40 (see fig. 2) of the driving shaft 4 and the central axis 50 (see fig. 2) of the driven shaft 5). The linear portion 81 has an upstream end located on the opposite side of the rotation direction of the driving gear 6 and the driven gear 7, and a downstream end located on the rotation direction side of the driving gear 6 and the driven gear 7.

The first branch portion 82 extends from the downstream end of the straight portion 81 in the rotation direction of the drive gear 6, and the second branch portion 83 extends from the downstream end of the straight portion 81 in the rotation direction of the driven gear 7.

In the present embodiment, the upstream end of the straight portion 81 is pointed toward the opposite side of the rotation direction of the driving gear 6 and the driven gear 7. In other words, the upstream end of the straight portion 81 is bent in a V-shape at the center so as to form an isosceles triangle. The angle of the bending is, for example, 60 to 120 degrees.

In the present embodiment, the tip end (center point) of the upstream end of the straight portion 81 coincides with the upstream-side intersection point a of the addendum circles 61 and 71. However, the tip end of the upstream end of the straight portion 81 does not necessarily have to coincide with the upstream-side intersection point a of the addendum circles 61 and 71, and may be located on the side of the upstream-side intersection point a in the rotational direction of the driving gear 6 and the driven gear 7, or may be located on the opposite side of the upstream-side intersection point a in the rotational direction of the driving gear 6 and the driven gear 7.

The width W of the straight portion 81 is preferably larger than the minimum distance between the root circle 62 of the driving gear 6 and the root circle 72 of the driven gear 7. For example, the width W of the linear portion 81 is 1.05 to 1.3 times the minimum distance between the root circle 62 of the driving gear 6 and the root circle 72 of the driven gear 7.

A branching point C (a central point of the downstream end of the straight line portion 81) between the first branching portion 82 and the second branching portion 83 in the groove 8 is located on the opposite side of the rotation direction of the drive gear 6 and the driven gear 7 with respect to the downstream side intersection point B of the addendum circles 61, 71. Therefore, the first branch portion 82 and the second branch portion 83 accurately overlap with the engagement region.

The length α of each of the first branch portion 82 and the second branch portion 83 is, for example, about 1/2 of the pitch P on the addendum circles 61 and 71 of the drive gear 6 and the driven gear 7. The tip end of the first branch portion 82 is a straight line orthogonal to the rotation direction of the drive gear 6, and the tip end of the second branch portion 83 is a straight line orthogonal to the rotation direction of the driven gear 7.

The inner side edge of the first branch portion 82 is parallel to the tip circle 61 of the drive gear 6, and is located at a position approximately a distance β from the tip circle 61 radially inward. The outer side edge of the first branch portion 82 is parallel to the root circle 62 of the drive gear 6, and is located at a position approximately a distance γ from the root circle 62 to the radially inner side. For example, the distances β and γ are about 1/8 of the minimum distance between the root circle 62 of the drive gear 6 and the root circle 72 of the driven gear 7.

Similarly, the inner side edge of the second branch portion 83 is parallel to the addendum circle 71 of the driven gear 7, and is located at a position approximately a distance β from the addendum circle 71 radially inward. The outer side edge of the second branch portion 83 is parallel to the root circle 72 of the driven gear 7, and is located at a position approximately a distance γ from the root circle 72 to the radially inner side. For example, the distances β and γ are about 1/8 of the minimum distance between the root circle 62 of the drive gear 6 and the root circle 72 of the driven gear 7.

As shown in fig. 3, the depth of the groove 8 gradually increases toward the rotation direction of the driving gear 6 and the driven gear 7 at the upstream end portion of the straight portion 81. Further, the depth of the groove 8 becomes gradually shallower from the downstream side end portion of the straight portion 81 to the first branch portion 82 toward the rotation direction of the drive gear 6, and becomes gradually shallower from the downstream side end portion of the straight portion 81 to the second branch portion 83 toward the rotation direction of the driven gear 7. In other words, the bottom of the groove 8 is inclined so as to be shallower from the center toward both sides. For example, both of the inclination angles of the inclined portions of the bottoms of the grooves 8 are about 15 degrees.

Next, the operation of the groove 8 will be described. In the first half of the step of meshing the drive gear 6 and the driven gear 7, the teeth of the other gear enter the tooth space of the one gear, and the volume of the tooth space is reduced. Therefore, the oil in the tooth grooves overflows in the axial direction of the gear, and the oil overflowed from the tooth grooves flows into the grooves 8. Therefore, the compression work (so-called stirring loss) of the gears to compress the oil is reduced. On the other hand, in the latter half of the meshing process of the drive gear 6 and the driven gear 7, the tooth space increases in volume by pulling out the tooth of one gear from the tooth space of the other gear. Thus, oil is immersed from the grooves 8 into the tooth grooves.

In the present embodiment, the end portions of the groove 8 on the rotation direction side of the driving gear 6 and the driven gear 7 are bifurcated along the rotation direction of the driving gear 6 and the driven gear 7, and thus the flow of oil in the groove 8 is also bifurcated. Therefore, in the latter half of the engagement process, oil having a circumferential velocity can be immersed from the groove 8 into the tooth groove. This can reduce acceleration work and can improve the efficiency of the parallel pump 1 compared with the conventional pump.

In the present embodiment, the tips of the first branch portion 82 and the second branch portion are linear, and therefore, the oil in the groove 8 can be guided toward the tooth groove by the blocking effect of the tips.

In the present embodiment, the bottom of the groove 8 is inclined so as to be shallower from the center toward both sides, so that the depth of the groove 8 can be changed in accordance with the change in the volume of the tooth groove.

(modification)

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, the groove 8 is not necessarily formed on both of the opposing surfaces 13 and 14 of the gear chamber 12, and may be formed on only one of the opposing surfaces 13 and 14.

The upstream end of the linear portion 81 of the groove 8 may be linear and parallel to the arrangement direction of the driving gear 6 and the driven gear 7. However, if the upstream end of the straight portion 81 is pointed toward the opposite side to the rotation direction of the driving gear 6 and the driven gear 7 as in the above-described embodiment, the oil having the circumferential velocity flowing along with the rotation of the driving gear 6 and the driven gear 7 can be smoothly introduced into the groove 8.

(summary)

The parallel pump of the present invention is characterized by comprising: a drive shaft to which a drive gear is fixed; a driven shaft to which a driven gear meshed with the drive gear is fixed; and a gear chamber that accommodates the drive gear and the driven gear and stores oil, wherein a groove that extends along a meshing area between the drive gear and the driven gear is formed in at least one of a pair of opposing surfaces of the gear chamber that face each other with the drive gear and the driven gear interposed therebetween, and an end portion of the groove on a side of a rotation direction of the drive gear and the driven gear is bifurcated along the rotation direction of the drive gear and the driven gear.

The groove may include, for example: a straight portion having an upstream end and a downstream end extending in a direction orthogonal to an arrangement direction of the driving gear and the driven gear; a first branch portion extending from a downstream end of the straight portion in a rotation direction of the drive gear; and a second branch portion extending from a downstream end of the straight portion in a rotation direction of the driven gear.

The upstream end of the straight portion may be sharpened toward the opposite side of the rotation direction of the driving gear and the driven gear. According to this structure, the oil having the circumferential velocity flowing with the rotation of the driving gear and the driven gear can be smoothly introduced into the groove.

The tip end of the first branch portion may be a straight line orthogonal to the rotation direction of the drive gear, and the tip end of the second branch portion may be a straight line orthogonal to the rotation direction of the driven gear. According to this structure, the oil in the groove can be guided toward the tooth groove by the blocking effect of the tips of the first branch portion and the second branch portion.

The branching point between the first branching portion and the second branching portion in the groove may be located on the opposite side of the rotation direction of the drive gear and the driven gear with respect to a downstream side intersection point of the addendum circle of the drive gear and the addendum circle of the driven gear. According to this structure, the first branch portion and the second branch portion accurately overlap with the engagement region.

The depth of the groove may be increased in the direction of rotation of the drive gear and the driven gear at an upstream end portion of the straight portion, and may be decreased in the direction of rotation of the drive gear from a downstream end portion of the straight portion to the first branch portion, and may be decreased in the direction of rotation of the driven gear from a downstream end portion of the straight portion to the second branch portion. According to this structure, the depth of the slot can be changed in accordance with the change in volume of the slot.

Claims

1. A parallel pump, comprising:

a drive shaft to which a drive gear is fixed;

a driven shaft to which a driven gear meshed with the drive gear is fixed; and

a gear chamber which accommodates the driving gear and the driven gear and stores oil,

a groove extending along a meshing area of the drive gear and the driven gear is formed in at least one of a pair of opposing surfaces of the gear chamber opposing each other through the drive gear and the driven gear,

the ends of the grooves on the rotation direction side of the driving gear and the driven gear are bifurcated along the rotation direction of the driving gear and the driven gear,

the groove includes: a straight portion having an upstream end and a downstream end extending in a direction orthogonal to an arrangement direction of the driving gear and the driven gear; a first branch portion extending from a downstream end of the straight portion in a rotation direction of the drive gear; and a second branch portion extending from a downstream end of the straight portion in a rotation direction of the driven gear.

2. A parallel pump according to claim 1, wherein,

the upstream end of the straight portion is sharpened toward the opposite side of the rotational direction of the drive gear and the driven gear.

3. A parallel pump according to claim 1 or 2, wherein,

the tip end of the first branch portion is a straight line orthogonal to the rotation direction of the drive gear, and the tip end of the second branch portion is a straight line orthogonal to the rotation direction of the driven gear.

4. A parallel pump according to claim 1 or 2, wherein,

a branching point between the first branching portion and the second branching portion in the groove is located on the opposite side of the rotation direction of the drive gear and the driven gear with respect to a downstream side intersection point of the addendum circle of the drive gear and the addendum circle of the driven gear.

5. A parallel pump according to claim 1 or 2, wherein,

the depth of the groove is increased toward the rotation direction of the drive gear and the driven gear at the upstream end of the straight portion, is decreased toward the rotation direction of the drive gear from the downstream end of the straight portion to the first branch portion, and is decreased toward the rotation direction of the driven gear from the downstream end of the straight portion to the second branch portion.