JP6724579B2 - Gear pump or gear motor - Google Patents

Description

The present invention relates to a gear pump or a gear motor including, for example, a drive gear and a driven gear.

Conventionally, in a gear pump, side plates are arranged on both sides of a gear housed in a casing. The high pressure area (constant) on the non-sliding surface side of the side plate is made slightly larger than the maximum area of the high pressure area on the sliding contact surface side so that the side plate is pressed against the gear side surface so as not to separate from the gear side surface.

Japanese Patent Laid-Open No. 2002-70754

In the gear pump, when the gear is driven, the high pressure and the low pressure are switched in three areas on the side of the sliding contact surface of the side plate. The three regions are a region near the low-pressure side end of the high-pressure introduction groove formed along the outer peripheral edge of each of the driving gear side and the driven gear side of the side plate, and a region near the meshing point of the driving gear and the driven gear. Refers to. However, the timing at which the low pressure portion switches to high pressure in the region on the drive gear side and the timing at which the high pressure portion switches to low pressure in the region on the meshing point side do not match, and the fluctuation range of the high pressure area in the three regions becomes large. In this case, the pressing force becomes excessive at the moment when the high-pressure area on the sliding contact surface side becomes small, and there is a problem of side plate wear or seizure.

Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a gear pump or a gear motor that can prevent the problems of side plate wear and seizure.

A gear pump or a gear motor according to a first aspect of the present invention includes a casing in which an internal space is formed,
A drive gear and a driven gear disposed in the internal space,
A side plate slidably contacting the end faces of the drive gear and the driven gear ,
The casing is
A suction passage, wherein the internal space and communicating and fluid is sucked at one end face,
And a discharge passage the inner space and the communicating and fluid is discharged at its other end face,
The driving gear and the driven gear is meshed with each other in the internal space, in contact with the inner peripheral surface of said internal space and partitioning the internal space into a high pressure region and low pressure region,
The side plate is
Two shaft holes through which the shafts of the drive gear and the driven gear respectively pass,
A suction side clearance groove and the arrangement to the discharge passage side by the discharge-side relief groove disposed in the suction passage side in between the two shaft hole,
And a high-pressure introduction groove communicating with the two shaft holes and said high pressure area extending along a circumferential direction at an end portion which is arranged on a line passing through the center in plan view,
When engagement point of the driving gear and the driven gear to match with the edge of the suction side clearance groove and the discharge side escape grooves, tooth surfaces of at least one of the high-pressure introduction groove side of the drive gear and the driven gear tip is characterized in that to match the low-pressure side end portion of the high-pressure introduction groove.

In this gear pump or gear motor, the drive gear and the driven gear rotate while meshing with each other. At this time, in the side plate of the gear pump, in the vicinity of the low-pressure side end of the high-pressure introduction groove, the high-pressure area usually decreases at a constant speed, but the low-pressure portion switches to high pressure at the moment when it reaches the minimum area, and the high-pressure area becomes It will be maximum. Further, in the vicinity of the meshing point, the high-pressure area usually increases at a constant speed, but the high-pressure portion switches to the low pressure at the moment when the maximum area increases, and the high-pressure area becomes the minimum. That is, the high-pressure area fluctuates periodically near the low-pressure side end of the high-pressure introduction groove and near the meshing point.
In the present invention, when the meshing points of the drive gear and the driven gear coincide with the edges of the suction side relief groove and the discharge side relief groove, the tip of the tooth surface on the high pressure introduction groove side of at least one of the drive gear and the driven gear has a high pressure. It coincides with the low pressure side end of the introduction groove. When the drive gear and the driven gear rotate from this state, the timing at which the low pressure portion switches to the high pressure near the low pressure side end of the high pressure introduction groove of at least one of the drive gear and the driven gear, and the high pressure portion switches to the low pressure near the meshing point. The timing matches. Therefore, the fluctuation range of the high pressure area on the sliding contact surface side of the side plate becomes small. As a result, even if the fluctuation range of the high pressure area becomes large, the pressing force that presses the side plate against the gear is prevented from becoming excessive at the moment when the high pressure area on the sliding contact surface side becomes small, and wear and seizure of the side plate are prevented. it can.

In a gear pump or gear motor according to the second invention, the side plates,
It has two of the high-pressure introduction groove extending along the circumferential direction in each of the two opposite ends centered arranged on a line passing through the axial hole in plan view,
When engagement point of the driving gear and the driven gear to match with the edge of the suction side clearance groove and the discharge side escape groove, the tip of each tooth surface of the drive gear and the driven gear of the high-pressure introduction groove It is characterized in that it coincides with the low-pressure side end.

In this gear pump or gear motor, when the meshing points of the drive gear and the driven gear coincide with the edges of the suction side relief groove and the discharge side relief groove, the tips of the tooth surfaces of the drive gear and the driven gear respectively have high pressure introduction grooves. Coincides with the low pressure side end of. When the drive gear and the driven gear rotate from this state, the timing at which the low pressure portion switches to high pressure near the low pressure side end of the high pressure introduction groove on the driving gear side and the driven gear side, and the timing at which the high pressure portion switches to low pressure near the meshing point. And match. Therefore, the fluctuation range of the high pressure area on the sliding contact surface side of the side plate becomes smaller. As a result, even if the fluctuation range of the high pressure area becomes large, the pressing force that presses the side plate against the gear is prevented from becoming excessive at the moment when the high pressure area on the sliding contact surface side becomes small, and wear and seizure of the side plate are prevented. it can.

In the first invention, the drive gear and the driven gear rotate while meshing with each other. At this time, in the side plate of the gear pump, in the vicinity of the low-pressure side end of the high-pressure introduction groove, the high-pressure area usually decreases at a constant speed, but the low-pressure portion switches to high pressure at the moment when it reaches the minimum area, and the high-pressure area becomes It will be maximum. Further, in the vicinity of the meshing point, the high-pressure area usually increases at a constant speed, but the high-pressure portion switches to the low pressure at the moment when the maximum area increases, and the high-pressure area becomes the minimum. That is, the high-pressure area fluctuates periodically near the low-pressure side end of the high-pressure introduction groove and near the meshing point.
In the present invention, when the meshing points of the drive gear and the driven gear coincide with the edges of the suction side relief groove and the discharge side relief groove, the tip of the tooth surface on the high pressure introduction groove side of at least one of the drive gear and the driven gear has a high pressure. It coincides with the low pressure side end of the introduction groove. When the drive gear and the driven gear rotate from this state, the timing at which the low pressure portion switches to the high pressure near the low pressure side end of the high pressure introduction groove of at least one of the drive gear and the driven gear, and the high pressure portion switches to the low pressure near the meshing point. The timing matches. Therefore, the fluctuation range of the high pressure area on the sliding contact surface side of the side plate becomes small. As a result, even if the fluctuation range of the high pressure area becomes large, the pressing force that presses the side plate against the gear is prevented from becoming excessive at the moment when the high pressure area on the sliding contact surface side becomes small, and wear and seizure of the side plate are prevented. it can.

In the second aspect of the invention, when the meshing points of the drive gear and the driven gear coincide with the edges of the suction side relief groove and the discharge side relief groove, the tips of the tooth surfaces of the drive gear and the driven gear are at the low pressure of the high pressure introduction groove. Match the side edge. When the drive gear and the driven gear rotate from this state, the timing at which the low pressure portion switches to high pressure near the low pressure side end of the high pressure introduction groove on the driving gear side and the driven gear side, and the timing at which the high pressure portion switches to low pressure near the meshing point. And match. Therefore, the fluctuation range of the high pressure area on the sliding contact surface side of the side plate becomes smaller. As a result, even if the fluctuation range of the high pressure area becomes large, the pressing force that presses the side plate against the gear is prevented from becoming excessive at the moment when the high pressure area on the sliding contact surface side becomes small, and wear and seizure of the side plate are prevented. it can.

The figure explaining the whole gear pump composition concerning the embodiment of the present invention. Sectional drawing in the II-II line of FIG. The front view which looked at the side plate which concerns on 1st Embodiment of FIG. 1 from the sliding contact surface side. IV-IV sectional view taken on the line of FIG. FIG. 5 is a sectional view taken along line VV of FIG. 3. The front view which looked at the side plate inserted in the internal space from the sliding contact surface side. The elements on larger scale in the state where the low-pressure side end of the drive-side high-pressure introduction groove and the tooth surface of the drive gear match. The front view which rotated the gearwheel from FIG. The graph which shows the magnitude|size of the high pressure area which arises in the side plate which concerns on 1st Embodiment. The graph which shows the magnitude|size of the high pressure area which arises in the side plate which concerns on a comparative example. The front view which looked at the side plate which concerns on 2nd Embodiment from the sliding contact surface side. The graph which shows the magnitude|size of the high pressure area which arises in the side plate which concerns on 2nd Embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment>
As shown in FIG. 1, a gear pump 1 includes a drive gear 2 and a driven gear 3 that mesh with each other, drive gear shafts 4a and 4b and driven gear shafts 5a and 5b that support the drive gear 2 and the driven gear 3, respectively. The drive gear 2, the driven gear 3, the drive gear shafts 4a and 4b, and the casing 6 that houses the driven gear shafts 5a and 5b are provided. The gear pump 1 according to the present embodiment sucks a working fluid supplied from a tank that stores a working fluid (for example, working oil) to increase the pressure, and then discharges the working fluid to supply the working fluid to a hydraulic device.

The casing 6 includes a main body 7 having an internal space 10 having a substantially 8-shaped cross section, a mounting 8 screwed to one end surface of the main body 7, and a cover 9 screwed to the other end surface of the main body 7. have. In the gear pump 1, the internal space 10 formed inside the main body 7 is closed by the mounting 8 and the cover 9. The casing 6 has bearing members 11 and 12 and bearing members 111 and 112 that support the drive gear 2 and the driven gear 3 that are inserted into the internal space 10.

As shown in FIGS. 1 and 2, each of the drive gear 2 and the driven gear 3 is configured as a spur gear and is inserted into an internal space 10 formed inside the casing 6. In the internal space 10, the drive gear shafts 4a and 4b are respectively extended from both end faces of the drive gear 2 in the axial direction, and the driven gear shafts 5a and 5b are respectively extended from both end faces of the driven gear 3 in the axial direction. Is set up. The drive gear shaft 4a is inserted through an insertion hole 8a formed in the mounting 8, and a drive means (not shown) is connected to the end of the drive gear shaft 4a.

In the gear pump 1, the drive gear 2 and the driven gear 3 are housed in the internal space 10 in a state of being meshed with each other, and the tooth tips thereof are in sliding contact with the inner peripheral surface of the internal space 10. As a result, the drive gear 2 and the driven gear 3 rotate while meshing with each other in the internal space of the casing 6. When the drive gear 2 and the driven gear 3 rotate, they abut on the inner peripheral surface of the inner space of the casing 6 to partition the inner space 10 into a low pressure region and a high pressure region.

1, the casing 6 supports a bearing member 11 that supports a drive gear shaft 4a that extends leftward from the drive gear 2 and a drive gear shaft 4b that extends rightward from the drive gear 2 in FIG. Bearing member 12 that operates. The bearing member 11 has a bearing 11a which is a bearing of the drive gear shaft 4a, and the bearing member 12 has a bearing 12a which is a bearing of the drive gear shaft 4b. Similarly, the casing 6 includes a bearing member 111 that supports the driven gear shaft 5a extending leftward from the driven gear 3 and a driven gear shaft extending rightward from the driven gear 3 in FIG. Bearing member 112 supporting 5b. The bearing member 111 has a bearing 111a which is a bearing of the driven gear shaft 5a, and the bearing member 112 has a bearing 112a which is a bearing of the driven gear shaft 5b.

Therefore, the bearing member 11 rotatably supports the drive gear shaft 4a by inserting the drive gear shaft 4a into the bearing 11a, and the bearing member 12 has the drive gear shaft 4b inserted into the bearing 12a. The drive gear shaft 4b is rotatably supported. Similarly, the bearing member 111 rotatably supports the driven gear shaft 5a by inserting the driven gear shaft 5a into the bearing 111a, and the bearing member 112 has the driven gear shaft 5b inserted into the bearing 112a. The driven gear shaft 5b is rotatably supported by.

Two side plates 20a and 20b are arranged on both sides of the drive gear 2 and the driven gear 3. Therefore, the two side plates 20a and 20b are arranged between the end surfaces of the drive gear 2 and the driven gear 3 and the bearing members 11 and 111 and the bearing members 12 and 112, respectively. Is in sliding contact with. The area of the high-pressure portion on the non-sliding contact surface side of the side plates 20a, 20b is slightly larger than the area of the high-pressure portion on the sliding contact surface side, and the sliding contact surface is pressed against the side surfaces of the drive gear 2 and the driven gear 3 to form a gap. Is designed to be as narrow as possible.

Grooves are formed on the end faces of the bearing members 11, 111 facing the side plate 20a, and elastic gaskets 11b are provided inside the groove. The gasket 11b divides the gap between the bearing members 11 and 111 and the side plate 20a into a low pressure region and a high pressure region. Similarly, a groove portion is formed on an end surface of each of the bearing members 12 and 112 facing the side plate 20b, and an elastic gasket 12b is provided inside each groove portion. The gasket 12b divides the gap between the bearing members 12 and 112 and the side plate 20b into a low pressure region and a high pressure region.

In the gear pump 1, as shown in FIG. 2, the main body 7 is provided with a suction passage 7a at one end surface thereof which communicates with a low pressure region of the internal space 10. A discharge passage 7b that communicates with a high pressure region of the internal space 10 is formed on the other end surface facing the suction passage 7a. The suction passage 7a and the discharge passage 7b are provided such that their centers are located at the centers between the rotation shafts of the drive gear 2 and the driven gear 3.

Therefore, in the gear pump 1, the pipe from the tank that stores the working fluid is connected to the suction passage 7a of the casing 6. A pipe leading to the hydraulic device is connected to the discharge passage 7b. When the drive gear shaft 4a of the drive gear 2 is rotated by a drive means (not shown), the driven gear 3 meshed with the drive gear 2 is rotated, whereby the inner peripheral surface of the internal space 10 and the drive gear 2 and the driven gear 3 are rotated. The working fluid in the space surrounded by the tooth surfaces is transferred to the discharge passage 7b side by the rotation of the gears, and the discharge passage 7b side is the high pressure side and the suction passage 7a side is the low pressure with the meshing point of the drive gear 2 and the driven gear 3 as a boundary. Be on the side.

When the working fluid is transferred to the discharge passage 7b side and the suction passage 7a side becomes negative pressure, the working fluid in the tank is sucked into the internal space 10 on the low pressure side through the pipe and the suction passage 7a. Then, the working fluid in the space surrounded by the inner peripheral surface of the internal space 10 and the tooth surfaces of the drive gear 2 and the driven gear 3 is transferred to the discharge passage 7b side by the rotation of the gear, is pressurized to a high pressure, and is discharged to the discharge passage 7b. And to the hydraulic equipment via piping.

Next, the side plates 20a and 20b according to the present invention will be described in detail. As shown in FIG. 3, the side plates 20a and 20b are 8-shaped plate-shaped members having two shaft holes 21 formed therein. The side plate 20a is fitted in the internal space 10 and is arranged between the drive gear 2 and the driven gear 3 and the bearing member 11 and the bearing member 111. The side plate 20b is fitted into the internal space 10 and is arranged between the drive gear 2 and the driven gear 3 and the bearing member 12 and the bearing member 112. Since the side plate 20a has the same shape as the side plate 20b, the same reference numerals are given to the same elements and the description thereof will be omitted.

The side plate 20b contacts the end faces of the drive gear 2 and the driven gear 3 in a state where the drive gear shaft 4a and the driven gear shaft 5a are inserted into the two shaft holes 21. Therefore, when the drive gear 2 and the driven gear 3 are rotated, the sliding contact surface 22 on the front side in FIG. 3 makes sliding contact with the end surfaces of the drive gear 2 and the driven gear 3. The surface of the side plate 20b opposite to the sliding contact surface 22 is a non-sliding contact surface 23 (see FIG. 4). In the state where the side plate 20b is inserted into the internal space 10, the non-sliding contact surface 23 faces the bearing member 12 and the bearing member 112 with a slight gap.

The side plate 20b includes a suction side relief groove 26 arranged on the suction passage 7a side between the two shaft holes 21, a discharge side relief groove 27 arranged on the discharge passage 7b side, and a drive gear shaft 4a side of the side plate 20b. And a driven-side high-pressure introduction groove 29 extending along the circumferential direction of the side plate 20b on the driven gear shaft 5a side. The suction side relief groove 26, the discharge side relief groove 27, the drive side high pressure introduction groove 28, and the driven side high pressure introduction groove 29 are provided on the sliding contact surface 22 of the side plate 20b.

The suction side escape groove 26 and the discharge side escape groove 27 are formed in the central portion of the side plate 20b in the longitudinal direction (the direction in which the line L1 extends in FIG. 3). The suction side relief groove 26 and the discharge side relief groove 27 have a groove shape (see FIG. 4) that is recessed from the outer side to the inner side of the side plate 20b.

The suction side clearance groove 26 and the discharge side clearance groove 27 are defined by an upper edge 31, a lower edge 32, an inner edge 33 (33a, 33b), and a bottom surface 34. The upper edge 31, the lower edge 32, and the inner edge 33 extend orthogonally to the sliding contact surface 22 in the thickness direction of the side plate 20b. The upper edge 31 is located on the drive gear 2 side, and the lower edge 32 is located on the driven gear 3 side. The inner edge 33 connects the inner edge of the upper edge 31 and the inner edge of the lower edge 32. The bottom surface 34 extends parallel to the sliding contact surface 22 and is continuous with the upper edge 31, the lower edge 32, and the inner edge 33.

In the assembled state of the gear pump 1, the suction side escape groove 26 communicates with the suction passage 7a (low pressure region) to have a low pressure. In the same state, the discharge side escape groove 27 communicates with the discharge passage 7b (high pressure region) and has a high pressure. When the gear pump 1 is assembled and driven as described later, the meshing point B between the drive gear 2 and the driven gear 3 coincides with the inner edge 33a on the suction side clearance groove 26 side, and the meshing point C is at the discharge side clearance groove 27. It is configured to match the inner edge 33b on the side (see FIG. 6). Further, when the gear pump 1 is driven, the area E located between the suction side relief groove 26 and the discharge side relief groove 27, that is, the vicinity of the meshing point of the drive gear 2 and the driven gear 3 is instantly changed from the high pressure state. After the entire surface is switched to the low pressure, the high-pressure area in the E region is expanded at a constant speed and the entire surface becomes the high pressure repeatedly.

The drive-side high-pressure introduction groove 28 and the driven-side high-pressure introduction groove 29 extend at ends (both ends in the longitudinal direction of the side plate 20b) arranged on the line L1 passing through the centers A of the two shaft holes 21 in plan view. ing. The drive-side high-pressure introduction groove 28 and the driven-side high-pressure introduction groove 29 are groove shapes (see FIG. 5) provided on the outer peripheral edge of the side plate 20b.

More specifically, the driving-side high-pressure introduction groove 28 and the driven-side high-pressure introduction groove 29 start from a high-pressure side end 37 communicating with the discharge-side escape groove 27 and have a high-pressure side end 37 around the center A of the shaft hole 21. And extends to the low-pressure side end portion 38 provided at a position forming a predetermined angle θ1. The value of the angle θ1 is not particularly limited. The high-pressure side end portion 37 here refers to an end portion of the drive-side high-pressure introduction groove 28 near the discharge passage 7b in the assembled state of the gear pump 1. On the other hand, the low-pressure side end portion 38 refers to the end portion of the drive-side high-pressure introduction groove 28 located on the opposite side of the high-pressure side end portion 37. The same applies to the high pressure side end portion 37 and the low pressure side end portion 38 of the driven side high pressure introduction groove 29.

The drive-side high-pressure introducing groove 28 and the driven-side high-pressure introducing groove 29 communicate with the discharge passage 7b in the assembled state of the gear pump 1 and have a high pressure. When the gear pump 1 is driven, the D region adjacent to the drive-side high-pressure introducing groove 28, that is, the vicinity of the low-pressure side end portion 38 of the drive-side high-pressure introducing groove 28 is instantly switched from the low-pressure state to the high-pressure side. The high pressure area in the region is reduced at a constant rate, and the entire surface becomes low pressure repeatedly. Similarly, the F region adjacent to the driven-side high-pressure introduction groove 29, that is, the vicinity of the low-pressure side end portion 38 of the driven-side high-pressure introduction groove 29 is instantly switched from the low-pressure state to the high-pressure side, and the high-pressure area in the F-region is constant. It decreases at the speed of and it becomes low pressure all over again.

Next, the rotating operation of the gear pump 1 will be described.

As shown in FIG. 6, when the drive gear 2 is rotated clockwise, the driven gear 3 is rotated counterclockwise. Due to the rotation of the drive gear 2 and the driven gear 3, oil (working fluid) is transferred from the suction passage 7a to the discharge passage 7b side, and the discharge passage 7b side has a high pressure at the mesh point B of the drive gear 2 and the driven gear 3 as a boundary. In the region, the suction passage 7a side becomes a low pressure region. When the mesh point B coincides with the inner edge 33a, the mesh point C coincides with the inner edge 33b. At this time, the tooth surfaces of the teeth 41 of the drive gear 2 coincide with the low-pressure side end portion 38 of the drive-side high-pressure introduction groove 28. However, in the present embodiment, when the meshing point B coincides with the inner edge 33a and the meshing point C coincides with the inner edge 33b, none of the tooth surfaces of the driven gear 3 has the low pressure side end portion of the driven side high pressure introduction groove 29. No match with 38.

The fact that the tooth surface forming the tooth 41 of the drive gear 2 coincides with the low pressure side end portion 38 of the drive side high pressure introducing groove 28 means that, as shown in FIG. This means that the tip 42a of the tooth surface 42 on the area side, in other words, the boundary between the tooth surface 42 on the low pressure area side and the tooth tip 43 coincides with the low pressure side end portion 38.

When the tooth surface of the drive gear 2 coincides with the low-pressure side end portion 38 of the drive-side high-pressure introduction groove 28, the tooth 41 of the drive gear 2 is moved from the tooth 41 of the drive gear 2 to the tooth groove 44 on the discharge passage 7b side via the drive-side high-pressure introduction groove 28. High pressure oil is introduced. At this time, as shown in the state 1 of FIG. 9, the high pressure area of the D region of the side plate 20b becomes zero. Further, since the high pressure oil is filled in the tooth space between the meshing point B and the meshing point C, the high pressure area in the E region of the closed portion becomes the maximum value b. The closed portion refers to a region between the inner edge 33a and the inner edge 33b. Each tooth groove 45 on the suction passage 7a side of the tooth 41 is maintained at a low pressure.

When the tooth surface of the drive gear 2 coincides with the low-pressure side end portion 38 of the drive-side high-pressure introduction groove 28, in the driven gear 3, via the driven-side high-pressure introduction groove 29, from the tooth 48 of the driven gear 2 to the discharge passage 7b side. High-pressure oil is introduced into each tooth space 49 of the. Each tooth groove on the suction passage 7a side of the tooth 48 is maintained at a low pressure.

As shown in FIG. 8, when the drive gear 2 and the driven gear 3 are further rotated, high-pressure oil is newly introduced into the tooth groove 45 adjacent to the tooth 41 via the driving-side high-pressure introduction groove 28, and 45 switches from low pressure to high pressure. This switching is performed in the tooth groove of the drive gear 2 that overlaps with the D area. As the tooth groove 45 is switched from the low pressure to the high pressure, as shown in FIG. 9, the high pressure area of the D region of the side plate 20b instantly rises from 0 to the maximum value a, and then in proportion to the rotation angle of the drive gear 2. The value drops to half the maximum value a (see state 1 to state 2 in FIG. 9).

At the same time, since the meshing point C moves along the line of action L3, the tooth groove on the suction passage 7a side from the meshing point C communicates with the suction passage 7a and switches from high pressure to low pressure. This switching is performed by the tooth groove of the drive gear 2 and the driven gear 3 which overlaps with the E region. When the tooth groove on the suction passage 7a side from the meshing point C is switched from high pressure to low pressure, the high pressure area in the E region instantly drops from the maximum value b to 0 and then reaches the maximum value in proportion to the rotation angle of the drive gear 2. It rises to half the value of b.

From the above, the total of the high-voltage areas generated on the sliding contact surface 22 side of the side plate 20b immediately before the switching in the state 2 is smaller by a than the total of the high-voltage areas generated on the sliding contact surface 22 side of the side plate 20b immediately after the switching. That is, the variation width of the total value of the high-pressure areas generated on the side of the sliding contact surface 22 of the side plate 20b is smaller than that in the comparative example described later. This is because the timing when the high-pressure area of the D region of the side plate 20b increases and the timing of the high-pressure area of the E region of the side plate 20b decrease according to the rotation angle of the gear (see state 1 in FIG. 9). Is achieved in.

As the high pressure area on the non-sliding contact surface side shown on the vertical axis of the graph in FIG. 9, the value of the minimum high pressure area for pressing the side plate 20b against the drive gear 2 and the driven gear 3 is shown. However, in order to surely press the side plate 20b, it is preferable that the high pressure area on the non-sliding contact surface 23 side is larger than the value indicated by the dotted line in FIG. The same applies to the graphs shown in FIGS. 10 and 12.

As a comparative example, in FIG. 10, when one meshing point of the drive gear and the driven gear coincides with one inner edge and the other meshing point coincides with the other inner edge, the tooth surface of the drive gear has a high pressure on the drive side. The high pressure area generated in the side plate of the gear pump that does not coincide with the low pressure side end of the introduction groove is shown. In this gear pump, the timing at which the high-pressure area of the side plate on the drive gear side increases and the timing at which the high-pressure area of the closed portion of the side plate decreases according to the rotation angle of the gear do not match (see state 3). Therefore, in state 4, the total of the high-voltage areas generated on the sliding contact surface side of the side plate immediately before switching in state 3 is smaller than the high-voltage areas generated on the sliding contact surface side of the side plate immediately after switching in state 3 by a+(b/2). Therefore, at the moment when the fluctuation range becomes larger than the fluctuation range of the high-pressure area of the present invention and the high-pressure area on the sliding contact surface side becomes small, the pressing force for pressing the side plate against the gear becomes excessive and abrasion or seizure of the side plate occurs.

[Characteristics of the gear pump 1 of the present embodiment]
The gear pump 1 of the first embodiment has the following features.

In the gear pump 1 or the gear motor, the drive gear 2 and the driven gear 3 rotate while meshing with each other on the side plate 20b of the gear pump 1. At this time, in the vicinity of the low-pressure side end portion 38 of the drive-side high-pressure introduction groove 28, the high-pressure area normally decreases at a constant speed, but the low-pressure portion switches to high pressure at the moment when it reaches the minimum area, and the high-pressure area becomes maximum. become. Further, in the vicinity of the meshing points B and C, the high pressure area normally increases at a constant speed, but at the moment when the maximum area is increased, the high pressure portion switches to low pressure, and the high pressure area becomes the minimum. That is, in the vicinity of the low-pressure side end portion 38 of the drive-side high-pressure introduction groove 28 and in the vicinity of the meshing points B and C, the high-pressure area fluctuates periodically.

In the present invention, when the meshing point B of the drive gear 2 and the driven gear 3 coincides with the inner edge 33a, and the meshing point C coincides with the inner edge 33b, the tooth surface of the drive gear 2 has the drive-side high-pressure introduction groove 28. It coincides with the low pressure side end 38. When the drive gear 2 and the driven gear 3 rotate from this state, the timing at which the low pressure portion switches to high pressure in the vicinity of the low pressure side end portion 38 of the drive side high pressure introduction groove 28 of the drive gear 2 and the high pressure portion in the vicinity of the meshing point become low pressure. The timing of switching is the same. As a result, the fluctuation range of the total value of the high-pressure areas generated on the sliding contact surface 22 side of the side plate 20b becomes small. Therefore, if the fluctuation range of the high-pressure area becomes large, it is prevented that the pressing force that presses the side plate 20b against the gear becomes excessive at the moment when the high-pressure area on the sliding contact surface 22 side becomes small, and the side plate 20b is not worn or seized. Can be prevented.

<Second Embodiment>
Next, the gear pump 1 of 2nd Embodiment which concerns on this invention is demonstrated. Since the configuration other than the side plates 60a and 60b is the same as that of the first embodiment, the same elements are designated by the same reference numerals and the description thereof will be omitted. The side plates 60a and 60b will be described in detail with reference to FIG. The same elements as those of the side plates 20a and 20b of the first embodiment are designated by the same reference numerals and description thereof will be omitted.

In the side plates 20a and 20b of the first embodiment, when the meshing point B coincides with the inner edge 33a and the meshing point C coincides with the inner edge 33b, none of the tooth surfaces of the driven gear 3 is the driven-side high pressure introduction groove 29. Does not match the low pressure side end 38 of On the other hand, in the side plates 60a and 60b of the second embodiment, when the meshing point B coincides with the inner edge 33a and the meshing point C coincides with the inner edge 33b, the tooth surfaces forming the teeth 41 of the drive gear 2 are changed. The low pressure side end portion 38 of the drive side high pressure introduction groove 28 coincides, and the tooth surface forming the teeth 48 of the driven gear 3 coincides with the low pressure side end portion 62 of the driven side high pressure introduction groove 29.

The fact that the tooth surface forming the tooth 48 of the driven gear 3 coincides with the low pressure side end portion 62 of the driven side high pressure introduction groove 29 means that of the tooth surface 63 forming the tooth 48 of the driven gear 3 on the low pressure region side. This means that the tip 63a coincides with the low pressure side end 62.

In the state shown in FIG. 11, high-pressure oil is introduced from the teeth 41 of the drive gear 2 into the tooth grooves 44 on the discharge passage 7b side via the drive-side high-pressure introduction groove 28, and the tooth grooves on the suction passage 7a side from the teeth 41 are introduced. 45 is maintained at a low pressure. Further, high-pressure oil is introduced from the teeth 48 of the driven gear 3 through the driven-side high-pressure introduction grooves 29 on the discharge passage 7b side, and each of the tooth grooves 65 on the suction passage 7a side of the teeth 48 is maintained at a low pressure. Has been done. High-pressure oil is introduced from the mesh point B to the discharge passage 7b side, and the suction passage 7a side from the mesh point B is maintained at a low pressure.

When the drive gear 2 and the driven gear 3 are rotated from this state, high pressure oil is newly introduced into the tooth groove 45 adjacent to the tooth 41, and the tooth groove 45 is switched from low pressure to high pressure. This switching is performed by the tooth groove 45 of the drive gear 2 that overlaps with the D region. As the tooth groove 45 is switched from low pressure to high pressure, as shown in state 5 to state 6 of FIG. 12, the high pressure area of the D region of the side plate 60b instantly rises from 0 to the maximum value a, and then the drive gear 2 The value drops to half the maximum value a in proportion to the rotation angle.

Similar to the drive gear 2 side, high pressure oil is newly introduced into the tooth groove 65 adjacent to the tooth 48 on the driven gear 3 side, and the tooth groove 65 is switched from low pressure to high pressure. This switching is performed by the tooth groove 65 of the driven gear 3 which overlaps with the F region. As the tooth groove 65 is switched from low pressure to high pressure, as shown in state 5 to state 6 of FIG. 12, the high pressure area of the F region of the side plate 60b instantly rises from 0 to the maximum value a, and then the drive gear 2 The value drops to half the maximum value a in proportion to the rotation angle.

At the same time, since the meshing point B moves, the tooth groove on the suction passage 7a side from the meshing point C communicates with the suction passage 7a and switches from high pressure to low pressure. This switching is performed by the tooth groove of the drive gear 2 and the driven gear 3 which overlaps with the E region. When the tooth groove on the suction passage 7a side from the meshing point C is switched from high pressure to low pressure, the high pressure area in the E region instantly drops from the maximum value b to 0 and then reaches the maximum value in proportion to the rotation angle of the drive gear 2. It rises to half the value of b.

From the above, in state 5, the sum of the high-pressure areas generated on the sliding contact surface 22 side of the side plate 60b immediately before the switching is smaller than the high-pressure areas generated on the sliding contact surface 22 side of the side plate 60b immediately after the switching by c=2a-b. Become. Since b is larger than a, the value c is smaller than the value a in the first embodiment. That is, the fluctuation range of the total value of the high pressure areas generated on the sliding contact surface 22 side of the side plate 60b becomes smaller. This is because the high pressure area of the D region of the side plate 60b increases, the high pressure area of the F region increases, and the high pressure area of the E region of the side plate 60b decreases according to the rotation angle of the gear. This is achieved by matching (see state 5 in FIG. 12).

[Characteristics of the gear pump 1 of the present embodiment]
The gear pump 1 including the side plates 60 (60a, 60b) of the second embodiment has the following features.

In this gear pump 1 or gear motor, when the meshing point B coincides with the inner edge 33a and the meshing point C coincides with the inner edge 33b, the tooth surface forming the tooth 41 of the drive gear 2 is the drive-side high-pressure introducing groove. 28 and the tooth surface of the tooth 48 of the driven gear 3 coincides with the low pressure side end portion 62 of the driven side high pressure introduction groove 29. When the drive gear 2 and the driven gear 3 rotate from this state, the low pressure portion switches to high pressure in the vicinity of the low pressure side end portion 38 of the drive side high pressure introduction groove 28 and in the vicinity of the low pressure side end portion 62 of the driven side high pressure introduction groove 29. , And the timing at which the high-voltage portion switches to low pressure in the vicinity of the meshing point matches. Therefore, the fluctuation range of the high pressure area on the sliding contact surface 22 side of the side plate 60 becomes smaller. With this, when the fluctuation range of the high-pressure area becomes large, it is prevented that the pressing force for pressing the side plate 60 against the gear is excessive at the moment when the high-pressure area on the sliding contact surface 22 side becomes small, and the side plate 60 is not worn or damaged. Burn-in can be prevented.

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configurations are not limited to these embodiments. The scope of the present invention is shown not only by the above description of the embodiments but also by the claims, and further includes meanings equivalent to the claims and all modifications within the scope.

In the above-described embodiment, the low-pressure side end portion 38 of the drive-side high-pressure introduction groove 28 is provided in the case where the tooth surface matches the low-pressure side end portion of the high-pressure introduction groove on either the drive gear 2 side or the driven gear 3 side. It coincided with the tooth surface tip 42a of the tooth 41. However, the invention is not limited to this, and the low pressure side end portion 38 of the driven side high pressure introduction groove 29 may coincide with the tooth surface tip of the tooth 48.

1 gear pump 2 drive gear 3 driven gear 6 casing 7a suction passage 7b discharge passage 10 internal space 20 (20a, 20b) side plate 21 shaft hole 26 suction side relief groove 27 discharge side relief groove 28 drive side high pressure introduction groove 29 driven side high pressure Introduction groove 33 (33a, 33b) Inner edge 38 Low-pressure side end 60 (60a, 60b) Side plate (second embodiment)
62 Low Pressure Side End (Second Embodiment)

Claims (2)

A casing with an internal space formed,
A drive gear and a driven gear disposed in the internal space,
A side plate slidably contacting the end faces of the drive gear and the driven gear ,
The casing is
A suction passage, wherein the internal space and communicating and fluid is sucked at one end face,
And a discharge passage the inner space and the communicating and fluid is discharged at its other end face,
The driving gear and the driven gear is meshed with each other in the internal space, in contact with the inner peripheral surface of said internal space and partitioning the internal space into a high pressure region and low pressure region,
The side plate is
Two shaft holes through which the shafts of the drive gear and the driven gear respectively pass,
A suction side clearance groove and the arrangement to the discharge passage side by the discharge-side relief groove disposed in the suction passage side in between the two shaft hole,
And a high-pressure introduction groove communicating with the two shaft holes and said high pressure area extending along a circumferential direction at an end portion which is arranged on a line passing through the center in plan view,
When engagement point of the driving gear and the driven gear to match with the edge of the suction side clearance groove and the discharge side escape grooves, tooth surfaces of at least one of the high-pressure introduction groove side of the drive gear and the driven gear A gear pump or a gear motor, wherein a tip of the gear pump is aligned with a low-pressure side end of the high-pressure introduction groove. The side plate is
It has two of the high-pressure introduction groove extending along the circumferential direction in each of the two opposite ends centered arranged on a line passing through the axial hole in plan view,
When engagement point of the driving gear and the driven gear to match with the edge of the suction side clearance groove and the discharge side escape groove, the tip of each tooth surface of the drive gear and the driven gear of the high-pressure introduction groove The gear pump or the gear motor according to claim 1, wherein the gear pump and the gear motor coincide with the low-pressure side end.

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