JP4726324B2 - Groove shape of side plate of gear pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a side plate of a circumscribed gear pump, and more particularly to a groove shape of the side plate.
[0002]
[Prior art]
In the external gear pump, the external teeth of the driving gear and the driven gear mesh with each other, the driving gear rotates and the driven gear rotates, thereby discharging the fluid from the suction port and discharging it from the opening to the outside. The discharged fluid is pressurized in accordance with the external load. Both gears are sandwiched between two side plates on both sides. There are movable and fixed side plates. The movable side plate receives discharge pressure (so-called “back pressure”) on its back surface (so-called “pressure loading type” or “pressure balance type”), and thereby the sliding rotation of both gears in close contact with the side surfaces of both gears. Increases the performance and suppresses internal fluid leakage. In other words, the use of the movable side plate increases the volumetric efficiency and torque efficiency (so-called “total efficiency etc.” or “pump efficiency”) of the pump. Therefore, the movable side plate is often used for an intermediate pressure / high pressure pump. On the other hand, the fixed side plate is separately fixed in the pump casing or is constituted by the inner wall of the pump casing itself. Since the fixed side plate cannot suppress the internal leakage of fluid as much as the movable side plate, the fixed side plate is often used for a low pressure / medium pressure pump.
[0003]
By the way, in the circumscribed gear pump, a fluid confinement chamber surrounded by the tooth surfaces of both gears and both side plate surfaces is formed at the meshing portion of both gears. The fluid confinement chamber includes a driving gear side confinement chamber and a driven gear side confinement chamber. Then, considering the presence of a groove to be described later on the side plate and the presence of backlash (that is, “invalid meshing point”), the volume of the indoor fluid is reduced by gradually reducing the volume of the driving gear side confinement chamber with the rotation of both gears. On the other hand, in the driven gear side confining chamber, the volume of the driven gear side confining chamber gradually increases with the rotation of both gears, and the indoor fluid is reduced in pressure. If the groove on the side plate described later is inappropriate, aeration (bubble formation of air dissolved in the fluid accompanying rapid pressure reduction of the fluid), cavitation (fluid itself accompanying rapid pressure reduction of the fluid) ) And pitting (damage of tooth surfaces and the like caused by bursting of bubbles in the fluid due to sudden super high pressure of the fluid or vibration) occur. The ultra high pressure and the low pressure are generated in different chambers, change between the ultra high pressure and the low pressure, and repeat with the rotation of the gear pump. The gear pump moves to the casing side and then moves away, causing the gear pump to vibrate, thereby reducing the life of the gear pump and generating noise. That is, the pump performance is reduced.
[0004]
The groove of the side plate is provided on the gear side surface of the side plate, and includes a discharge port side groove (first groove) communicating with the discharge port and a suction port side groove (second groove) communicating with the suction port. And, the conventional groove is generally responsible for the function of suppressing the ultra-high pressure of the fluid in the chamber by communicating the confining chamber on the driving gear side with the discharge port, while the groove on the outlet side is on the driven gear side. Controls the low pressure of the fluid in the room by communicating the confinement chamber with the suction port. The occurrence of the inconvenience is suppressed by both functions. Of course, if both grooves communicate with each other directly or both grooves communicate with each other through the fluid confinement chamber, so-called “blow-through” occurs, and the volumetric efficiency decreases. Therefore, various groove shapes taking into consideration the meshing rate have been put into practical use.
[0005]
[Problems to be solved by the invention]
By the way, first of all, in order to suppress the above problems, it is indispensable to suppress the ultrahigh pressure as well as to prevent the above-mentioned blow-by. In addition, regarding the pressure reduction, when the side plate is a movable side plate, there is no particular problem. The reason is that, as described above, the movable side plate receives back pressure and is in close contact with the side surfaces of both gears to enhance the sliding rotation of both gears. That is, the existence of a low pressure that does not reduce the back pressure is preferable. Of course, no trouble occurs when the side plate is a fixed side plate.
[0006]
Incidentally, backlash also occurs at adjacent points between the driving gear side confinement chamber and the driven gear side confinement chamber. Therefore, in a gear pump having a grooved side plate, the ultra-high pressure generated in the driving gear side confinement chamber and the low pressure generated in the driven gear side confinement chamber are alleviated by communicating both chambers via backlash. Is done. However, when the gear pump rotates at a high speed, the flow rate per unit time flowing through a narrow backlash (proportional to the product of the opening area of the backlash and the square root of the differential pressure across the backlash) cannot keep up with the rotational speed of the gear pump, so-called oil There is a tendency for locks to occur, limiting the pressure relief through backlash. For this reason, in the circumscribed gear pump, as described above, first of all, it is essential to suppress the super high pressure by the groove shape.
[0007]
However, according to the above-mentioned conventional various groove shapes, it is the actual state that does not have the groove shape that is characteristic of the present invention whose details will be described later (for example, Japanese Examined Patent Publication No. 63-45513).
[0008]
In view of the above prior art, an object of the present invention is to provide an improved groove shape. More specifically, “no blow-through” is, of course, a groove in the side plate of the gear pump that can achieve at least one, for example, noise can be better suppressed, overall efficiency can be improved better, and assembly errors are less likely to occur. The shape is provided.
[0009]
[Means for solving the problems and effects]
In order to achieve the above object, the groove shape of the side plate of the gear pump according to the present invention is as follows. First, the first groove communicated with the discharge port and the second groove communicated with the suction port of the driving gear and the driven gear. A side plate is provided on the side surface side, and the driven gear rotates by meshing between the external teeth of both gears, so that the driven gear rotates, so that the fluid from the suction port can be discharged and discharged from the port to the outside. In the external gear pump in which a fluid confinement chamber composed of a driving gear side confining chamber and a driven gear side confining chamber is formed in the meshing portion of the teeth, surrounded by the tooth surfaces of both gears and both side plates.
The first and second grooves are shaped to be simultaneously isolated from the fluid confinement chamber at the end of meshing of the meshing teeth on the far side of both gears,
The first groove has a shape that is isolated from the driven gear side confining chamber when the driven gear rotates by a predetermined angle from the minimum volume of the driven gear side confining chamber, and
The second groove is characterized in that it has a shape communicating with the driving gear side confinement chamber almost simultaneously with the start of rotation of the driving gear from the minimum capacity of the driving gear side confinement chamber.
[0010]
According to the first configuration,
(1) Since the first and second grooves are shaped to be simultaneously isolated from the fluid confinement chamber at the end of meshing of the meshing teeth on the far side of both gears, and the second groove is in the confinement chamber on the driving gear side. Since the shape is communicated with the drive gear side confinement chamber almost simultaneously with the start of rotation of the drive gear from the minimum capacity, the ratio of the drive gear side containment chamber due to the rotation of the drive gear is small, so the drive gear side containment chamber The ultra high pressure at the minimum volume can be suppressed.
(2) Since the first groove is shaped to be isolated from the driven gear side confining chamber when the driven gear rotates by a predetermined angle from the minimum volume of the driven gear side confining chamber, the following driven gear side Unnecessary pressure reduction accompanying a gradual increase in the volume of the confinement chamber can be prevented.
(3) That is, the effects of the above (1) and (2) are synergistic, and inconveniences such as aeration, cavitation and pitching hardly occur, noise is greatly reduced, and the service life of the gear pump can be extended. Of course, no blow-through phenomenon occurs.
(4) Since the second groove is shaped to communicate with the driving gear side confining chamber almost simultaneously with the start of rotation of the driving gear from the minimum capacity of the driving gear side confining chamber, the driving gear can be further slightly When rotating, the ultra high pressure at the minimum volume of the drive gear side confinement chamber is released into the second groove.
(5) According to the above configuration, the first and second grooves are axisymmetric with respect to the meshing action line of the gear pump and are asymmetric with respect to the pitch point. Therefore, the operator can visually recognize the difference between the side plates, and therefore, it is difficult to cause an assembly error such as assembling the left and right side plates at the time of assembly, so that the pump efficiency is not lowered or broken.
[0011]
Secondly, in the first groove shape, the shape of the second groove communicated with the driving gear side confining chamber almost simultaneously with the start of rotation of the driving gear from the minimum capacity of the driving gear side confining chamber. While the gear rotates by a predetermined angle, the width in the direction between the two gears may be smaller than the width of the driving gear side confining chamber when the driving gear side confining chamber is at the minimum volume.
[0012]
According to the second configuration, since the ultra-high pressure at the minimum volume of the drive gear side confining chamber is gently opened into the second groove, it is possible to prevent the generation of an opening sound (noise).
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. FIG. 1 shows the meshing portion of both gears G1 and G2 in the external gear pump in which the driving gear G1 rotates clockwise Y1 and the driven gear G2 meshing with the driving gear G1 rotates counterclockwise Y2.
[0014]
In FIG. 1, Po is a pitch point, L1 is a line passing through the pitch point Po to a rotation shaft (not shown) of both gears G1, G2, (hereinafter, “inter-axis line L1”), L2 is an action line, and L3 is a gear G2. , L4 is a pitch circle common tangent (hereinafter “common tangent L4”), g10 and g20 are meshed at the ends of both gears G1 and G2. Matching external teeth (hereinafter “teeth g10, g20”), g11, g22 are external teeth meshing after both gears G1, G2 (hereinafter “teeth g11, g22”), R1 is a driving gear side confinement chamber, R2 is driven Gear side confinement chamber, K is a meshing point, Ko is a meshing invalid point where backlash exists, Ks is a meshing start point (see FIG. 1 (b)), and Ke is a meshing end point (see FIG. 1 (d)). Show. Note that all of the above element names are the detailed description of FIG. 1 and are unnecessary in the description of the present embodiment below, while there are other elements than those described above in the description of the present embodiment. Necessary elements other than the above are added as needed together with their reference numerals.
[0015]
The side plate grooves according to the present embodiment refer to the discharge port side groove M1 and the suction port side groove M2 in FIG. Since the side plate is the paper surface itself, the discharge port is located on the left side in the figure, and the suction port is located on the right side in the figure, so that it is not shown. The groove M1 is formed on the side plate surface along the continuous lines M11 to M15 and communicates with the discharge port. On the other hand, the groove M2 is formed on the side plate surface along the continuous lines M21 to M25 and communicates with the suction port. Details are as follows.
For convenience of explanation, V1 is the volume of the driving gear side confining chamber R1, V1min is the minimum volume, V1max is the maximum volume, V2 is the volume of the driven gear side confining chamber R2, V2min is the minimum volume, and V2max is The maximum volume, R is the fluid confinement chamber, V is the total volume of the fluid confinement chamber R (V = V1 + V2), Vmin is its minimum total volume (Vmin> V1min + V2min), and Vmax is the maximum total volume. And
[0016]
In FIG. 1, (a) shows a state where the tooth g10 meshes with the tooth 20 at the meshing point K, and the center of the tip of the tooth g10 is located on the inter-axis line L1. In this state, the volume V2 of the chamber R2 is the minimum V2min. The groove M2 is completely isolated from the chambers R1 and R2 because the continuous lines M21 to M25 are far away from the chambers R1 and R2 toward the suction port. On the other hand, the groove M1 communicates with the chamber R1 because the tooth g11 has not yet meshed with the tooth 22 (ineffective meshing point Ko on the left side of the figure) and the line segment M14 is located in the chamber R1. Since the line segment M12 is located in the chamber R2, it communicates with the chamber R2. That is, the groove M1 discharges both chambers R1 and R2 to communicate with the discharge port.
[0017]
(B) is a state in which the gears G1, G2 have been rotated by approximately 3 ° from the state (a). In this embodiment, the closer tooth g11 starts to mesh with the tooth 22 at the point Ks in this state. That is, the point Ks is a meshing start point. Accordingly, the chamber R1 does not occur correctly in the state (a), but occurs for the first time in the state (b). That is, in this state, the volume V1 of the chamber R1 is the maximum V1max, while the volume V2 of the chamber R2 is gradually increased slightly than the minimum volume V2min in the state (a). Here, the groove M2 remains isolated from the chambers R1, R2, while the groove M1 remains in communication with the chamber R1 because its line segment M14 remains in the chamber R1. However, in this embodiment, the groove M1 has its line segment M12 in contact with the chamber R2 in this state, and in this state, the groove M1 is isolated from the chamber R2. That is, only the groove M1 discharges the chamber R1 and communicates with the outlet.
[0018]
(C) is a state in which the two gears G1, G2 have been advanced and rotated by approximately 7 ° from the state (b). In this state, the volume V2 is further increased more than the state (b), while the volume V1 is further gradually decreased to be substantially equal to each other (V2≈V1) (depending on the specifications of the gear pump, Some have different close engagement ratios and disengagement engagement ratios, and in such a gear pump, “V2 ≠ V1”). In this state, the total volume V of the fluid confinement chamber R becomes the minimum Vmin (as described above, Vmin> V1min + V2min). Here, the isolation or communication state of the grooves M1, M2 with respect to the chambers R1, R2 is the same as the state (b) as shown in the figure, but the volume chambers V1, V2 of the chambers R1, R2 are in the state (b). Is different.
[0019]
(D) shows a state in which both gears G1 and G2 have been rotated by approximately 7 ° from the state (c). In this embodiment, the far-away tooth g10 is separated from the tooth 20 at the point Ke in this state. That is, the point Ke is a meshing end point. Therefore, the volume V2 of the chamber R2 is the maximum V2max in this state. On the other hand, the volume V1 of the chamber R1 is gradually reduced from the volume V1 in the state (c). Here, in the groove M2, the line segment M22 passes over the meshing end point Ke and comes into contact with the chamber R2 at this point Ke, and the groove M1 has a line segment M14 on the meshing point K between the tooth g11 and the tooth 22. And is in contact with the chamber R1. The continuous lines M11 to M13, M15, M21, and M23 to M25 of both grooves M1 and M2 are not located in the chambers R1 and R2. Therefore, only in this state, the grooves M1 and M2 are both isolated from the chambers R1 and R2.
[0020]
(E) shows a state in which both gears G1, G2 have been rotated by approximately 3 ° from the state (d). In this state, the volume V1 of the chamber R1 is the minimum V1min. Here, the groove M2 has already connected the chamber R2 to the suction port, but the chamber R1 is isolated from the grooves M1 and M2. However, in this state, the chamber R2 is in contact with the line segment M14. Accordingly, when both the gears G1 and G2 are further advanced, the chamber R1 starts to communicate with the suction port via the groove M2.
[0021]
In summary, the groove M1 is isolated from the chamber R2 when the volume V2 of the chamber R2 is advanced by a predetermined angle from the state (a) when the volume V2 of the chamber R2 is minimum V2 min. On the other hand, the groove M2 starts to communicate with the chamber R1 when the driving gear G2 rotates even a little from the state (e) when the volume V1 of the chamber R1 is the minimum V1min. Both grooves M1 and M2 are isolated from both chambers R1 and R2 only when the far-away tooth g10 is located at the engagement end point Ke with the tooth g20. Therefore, the grooves M1 and M2 are non-axisymmetric with respect to the common tangent line L4 and are asymmetric with respect to the pitch point Po.
[0022]
Next, the operational effects of this embodiment are shown in FIG. In order to better understand the function and effect, FIG. 2 shows a comparative example having a groove shape based on the general technical idea already described in the section of “Prior Art”, and FIG. 4 shows the function and effect. Here, for comparison between the two, FIGS. 2 (a) to 2 (e), which are comparative examples, in terms of the advance angle of the two gears G1 and G2, are shown in FIG. 1 (a) to FIG. Correspondingly, FIGS. 4A to 4C, which are comparative examples, correspond to FIGS. 3A to 3C of this embodiment in the order shown.
[0023]
First, a comparative example of FIG. 2 will be briefly described. The groove Ma (corresponding to the groove M1) is isolated from the chamber R2 when the volume V2 of the chamber R2 is in the state (a) when the volume V2 is the minimum V2 min. On the other hand, the groove Mb (corresponding to the groove M2) starts to communicate with the chamber R1 when the driving gear G2 rotates even a little from the state (e) when the volume V1 of the chamber R1 is the minimum V1 min, as in the present embodiment. Both grooves Ma and Mb are isolated from the chambers R1 and R2 only when the total volume V of the chamber R is the minimum value Vmin (c). Accordingly, the grooves Ma and Mb are non-axisymmetric with respect to the common tangent line L4, but are substantially point symmetric with respect to the pitch point Po.
[0024]
FIG. 3 based on the present embodiment and FIG. 4, which is a comparative example, are conceptual diagrams assuming that there is almost no backlash for the sake of easy explanation (thus, they are not actually measured values). The difference in effect between the example and the prior art is shown better. In other words, the practical suitability of this embodiment at the time of high-speed rotation of the gear pump that cannot expect much pressure relaxation action via backlash is better shown. Each horizontal axis indicates the advance angle (that is, “rotation”) of both gears G1, G2, and each advance point (a) to (e) is shown in FIG. 1 of the present embodiment and FIG. Corresponding to (e) in this figure order. The vertical axis shows the total fluid confinement volume V (= V1 + V2) in (A), (B) shows the fluid pressure PR2 in the chamber R2, and (C) shows the fluid pressure PR1 in the chamber R1.
[0025]
That is, each hatched portion in FIGS. 3A and 4A indicates a “completely confined area”. The white portion indicates a complete communication area.
[0026]
[1] The lower volume V1 (in the chamber R1 side) of the shaded portion indicates the advance point (d) to (e) in FIG. 3A and the advance point (c) in FIG. ~ (E) shorter than the region. For this reason, the ultrahigh pressure PR1max-A generated at the advance point (e) in FIG. 3C is significantly lower than the ultrahigh pressure PR1max-B generated at the advance point (e) in FIG. Become.
[0027]
However, if left as it is (that is, in this embodiment as well, as in the comparative example, “the groove Ma is isolated from the chamber R2 when the volume V2 of the chamber R2 is in the state (a) when the volume V2 of the chamber R2 is minimum”). Since the advance angle points (a) to (d) in FIG. 3 (A) are longer than the advance angle points (a) to (c) in FIG. 4 (A), the advance in FIG. The low pressure PR2 generated at the corner point (d) becomes the low pressure PR2min-a1 indicated by the dotted line in FIG. 4, and is significantly lower than the low pressure PR2min-b generated at the advance point (c) in FIG.
[0028]
[2] However, in the present embodiment, as described above, “the groove M1 enters the chamber R2 when the volume V2 of the chamber R2 is advanced by a predetermined angle from the state (a) when the volume V2 of the chamber R2 is minimum V2 min. Therefore, as shown in the solid line in FIG. 3B, the low pressure PR2 becomes the low pressure PR2min-a, and a significant decrease can be suppressed. .
[0029]
[3] That is, according to the above [1] and [2], an ultrahigh pressure PR1max-A lower than that of the comparative example and a somewhat lower pressure than that of the comparative example are generated. Moreover, as already described, the low pressure does not affect the pump performance such as noise and life so much. Of course, since the backlash is actually generated even when the gear pump rotates at a high speed, the pressure relaxation action through the backlash can be expected to be relatively larger than that of the prior art. That is, according to the present embodiment, inconveniences such as aeration, cavitation and pitching are unlikely to occur, and noise is greatly reduced. Here, the noise is the vibration of the entire gear pump, so the service life of the gear pump is extended.
[0030]
[4] Further, as described above, the grooves M1 and M2 of this embodiment are non-axisymmetric with respect to the common tangent line L4 and are asymmetric with respect to the pitch point Po. Therefore, the right and left side plates are mixed at the time of assembly, and the pump efficiency is not lowered or damaged. On the other hand, in the comparative example, the grooves Ma and Mb are axisymmetric with respect to the common tangent line L4, but are substantially point symmetric with respect to the pitch point Po. Accordingly, it is often the case that the right and left side plates are mixed at the time of assembly to cause a decrease in pump efficiency and pump performance or to cause damage.
[0031]
That is, the above-mentioned operational effects [1] to [3] are basically obtained by the present embodiment in which the first and second grooves M1 and M2 are engaged with the meshing teeth g10-g20 on the far side of both the gears G1 and G2. The shape is such that it is simultaneously isolated from the fluid confinement chamber R at the time point Ke (first condition). Further, the first groove M1 has a predetermined angle (the driven gear G2 has a predetermined angle (from the minimum volume V2min of the driven gear side confinement chamber R2). It is shaped so as to be isolated from the driven gear side confining chamber R2 when it is rotated by the amount corresponding to the length of the line segment M13 (second condition), and the second groove M2 has a minimum volume of the driving gear side confining chamber R1. This is obtained because the shape (third condition) communicated with the drive gear side confinement chamber R1 is satisfied almost simultaneously with the start of rotation of the drive gear G1 from V1min.
[0032]
Next, the example of the aspect based on the said Example is illustrated with the effect.
[0033]
The “communication shape” in the third condition in the above embodiment is further “the width in the direction between the gears G1 and G2 (the width in the vertical direction in the drawing) while the driving gear G1 rotates by a predetermined angle, It is desirable to make it smaller than the width of the driving gear side confining chamber R1 when the driving gear side confining chamber R1 has a minimum volume V1min.
[0034]
The third condition “the second groove M2 in the above embodiment is communicated with the driving gear side confinement chamber R1 almost simultaneously with the start of rotation of the driving gear G1 from the minimum volume V1min of the driving gear side confinement chamber R1. "Is the same shape as this part in the comparative example. In this case, depending on the specifications of the gear pump, if the advance point (e) in FIG. 4C is borrowed and described, the minimum volume as shown on the advance side from the advance point (e) is shown. It is also conceivable that the ultrahigh pressure PR1max-B at V1min is suddenly opened in the groove M2 and the open sound (noise) is continuously generated. That is, the vibration of the pump.
However, as in the above-described embodiment, “while the driving gear G1 rotates by a predetermined angle, the driving gear side confining chamber R1 has a width in the direction between the gears G1 and G2 and the minimum capacity V1min of the driving gear side confining chamber R1. 3), the super high pressure PR1max-B with the minimum volume V1min is gradually opened into the groove M2, as shown on the advance side from the advance point (e) in FIG. Therefore, the generation of open sound (noise) can be prevented.
[Brief description of the drawings]
FIG. 1 is a partially enlarged view of a meshing portion of an embodiment.
FIG. 2 is a partially enlarged view of a meshing portion of a comparative example.
FIG. 3 is a characteristic graph showing the effects of the embodiment.
FIG. 4 is a characteristic graph of effects of a comparative example.
[Explanation of symbols]
G1: driving gear, G2: driven gear, g10, g20, 11, g22: external teeth, K: meshing point, Ko: meshing invalid point, Ks: meshing start point, Ke: meshing end point, L1: axis line L2: action line, L4: common tangent, M1: first groove (discharge port side groove), M2: second groove (suction port side groove), Po: pitch point, R1: driving gear side confining chamber, R2: driven Gear side fluid confinement chamber, R: Fluid confinement chamber, V: Fluid confinement total volume, V1: Drive gear side confinement volume, V2: Drive gear side confinement volume, Vmin: Fluid confinement minimum total volume, V1min : Minimum confining volume on the driving gear side, V2min: Minimum confining volume on the driven gear side.

Claims (1)

A side plate having a first groove (M1) communicating with the discharge port and a second groove (M2) communicating with the suction port on the side of the driving gear (G1) and the driven gear (G2) is provided. G1, G2) external teeth (g10, g11, g20, 22) meshing (g10-g20, g11-g22) causes the driving gear (G1) to rotate and the driven gear (G2) to rotate. It is possible to discharge the fluid from the discharge port to the outside, and the meshing part (g10-g20, g11-g22) of the external teeth (g10, g11, g20, 22) In the external gear pump in which a fluid confinement chamber (R) consisting of a driving gear side confinement chamber (R1) and a driven gear side confinement chamber (R2) surrounded by each tooth surface and both side plates is generated.
The first and second grooves (M1, M2) are simultaneously isolated from the fluid confinement chamber (R) at the end of meshing of the meshing teeth (g10-g20) on the far side of both gears (G1, G2). Shape, and
The first groove (M1) is isolated from the driven gear side confinement chamber (R2) when the driven gear (G2) rotates by a predetermined angle from the minimum volume (V2min) of the driven gear side confinement chamber (R2). A shape to be made, and
The second groove (M2) is communicated with the drive gear side confinement chamber (R1) almost simultaneously with the start of rotation of the drive gear (G1) from the minimum volume (V1min) of the drive gear side containment chamber (R1). The groove shape of the side plate of the gear pump, characterized by

Images