Trapped oil-free gear pump

Abstract

The invention relates to the technical field of gear pumps, and discloses an oil-trapping-free gear pump which comprises a shell, a driving gear and a driven gear which are meshed with each other are arranged in the shell, gear tooth ends of the driving gear and the driven gear are turned by set lengths to form first sections, non-turned parts are second sections, and the sections on the driving gear and the driven gear are the same in position. The first section and the second section are symmetrical about the middle position at the end part of the gear tooth; the overlapping coefficient of the first segment on the gear teeth of the driving gear and the driven gear is equal to 1, and the overlapping coefficient of the second segment is greater than 1, so that the gear teeth of the first segment do not enter a meshing state when the gear teeth of the second segment enter the meshing state; the oil trapping phenomenon is effectively solved, gear teeth are turned more conveniently, and only one part of the upper section and one part of the lower section need to be turned off; and the use of a side plate is eliminated, and a side plate structure with an unloading groove does not need to be mounted, so that the manufacturing cost of the gear pump is saved, and the overall axial volume of the gear pump is smaller.

Description

Technical Field

[0001] The invention relates to the technical field of gear pumps, in particular to an oil-free gear pump. Background Art

[0002] A gear pump is a positive displacement pump that delivers liquid by rotating a pair of meshing gears in the pump body. The two gears of the gear pump are constantly meshing and disengaging to form a continuous liquid delivery process. During the operation of the gear pump, since the overlap coefficient of the gears is designed to be greater than 1, to ensure the continuous oil supply of the gear pump, two pairs of teeth will be meshed at the same time. During this period, part of the oil will be trapped in the closed oil chamber formed by the two pairs of gears. This closed oil chamber is neither connected to the suction chamber nor to the pressure chamber. When the gear pump is running, the volume of the closed oil chamber will first decrease and then increase. When the volume decreases, the oil is compressed, and when the volume increases, a partial vacuum is formed. The compression of the oil will cause the pressure to increase, which may cause the bubbles in the oil to collapse, generating vibration and noise. This pressure shock and cavitation caused by the change in closed volume is called oil trapping.

[0003] In order to solve the oil trapping problem of gear pumps, current gear pumps use side plates to add unloading grooves to avoid structural oil trapping, but the direction of the liquid jet will impact the material of the side plate. At the same time, the addition of the side plate increases the axial volume of the gear pump. The use of dual-module processing and tooth surface processing unloading grooves can also solve the oil trapping problem, but the dual-module processing of gears requires adjusting the module of gear processing, and it is difficult to process the unloading grooves on the tooth surface, and the overall processing difficulty is relatively high. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a gear pump without oil entrapment, which effectively solves the oil entrapment problem. The gear turning process is more convenient, and only a part of the upper and lower sections need to be turned off, which reduces the processing difficulty. At the same time, the use of side plates is eliminated, and there is no need to install a side plate structure with a relief groove, which saves the manufacturing cost of the gear pump. Since there is no need to install a side plate, the overall axial volume of the gear pump is smaller.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A gear pump without oil trapping comprises a housing, wherein a driving gear and a driven gear meshing with each other are arranged in the housing, the gear tooth ends of the driving gear and the driven gear are turned to a set length to form a first segment, and the unturned portion is a second segment, the segment positions on the driving gear and the driven gear are the same, and the first segment and the second segment are symmetrical about the middle position at the gear tooth ends; the overlapping coefficient of the first segment on the gear teeth of the driving gear and the driven gear is equal to 1, and the overlapping coefficient of the second segment is greater than 1, so that when the gear teeth of the second segment enter the meshing state, the gear teeth of the first segment do not enter the meshing state.

[0007] As a further implementation, an auxiliary ring for sealing and supporting is installed between the driving gear and the driven gear and the inner wall of the shell, the outer side of the auxiliary ring is in close contact with the inner wall of the shell, and the inner side is in close contact with the end of the first segment of the gear tooth end.

[0008] As a further implementation, a limiting structure is provided on the inner wall of the shell for limiting the auxiliary ring so that the auxiliary ring is relatively fixed to the inner wall of the shell.

[0009] As a further implementation, the first segment is a planar structure with a uniform width.

[0010] As a further implementation manner, a width of the auxiliary ring is adapted to a turning length of the first segment.

[0011] As a further implementation, a groove is provided on the side edge of the auxiliary ring to achieve pressure equalization.

[0012] As a further implementation, the gear tooth end is divided into three groups of segments, wherein the second segment is arranged in the middle of the gear tooth, and both ends of the second segment are the first segments.

[0013] As a further implementation manner, the length of the second segment is twice the length of the first segment.

[0014] As a further implementation, the gear tooth end is divided into three groups of segments, wherein the first segment is arranged in the middle of the gear tooth, and the two ends of the first segment are the second segments.

[0015] As a further implementation, the length of the first segment is one third of the length of the gear tooth.

[0016] The beneficial effects of the present invention are as follows:

[0017] 1. The present invention forms three groups of segments by turning the end of the gear teeth, namely the second segment and the first segment. The overlap coefficient of the first segment on the gear teeth of the driving gear and the driven gear is equal to 1, and the overlap coefficient of the second segment is greater than 1, which effectively solves the oil trapping phenomenon. The gear turning process is more convenient, and only a part of the upper and lower segments need to be turned off, which reduces the processing difficulty. At the same time, the use of the side plate is eliminated, and there is no need to install the side plate structure with the unloading groove, which saves the manufacturing cost of the gear pump. Since there is no need to install the side plate, the overall axial volume of the gear pump is smaller.

[0018] 2. The present invention adds an auxiliary ring between the outer side of the first segment and the inner wall of the shell, which fills the gap between the first segment and the inner wall of the shell and plays a supporting and sealing role; a groove is set on the side of the auxiliary ring to play a role of pressure equalization.

[0019] 3. The present invention provides a limiting structure in the housing to fix the relative position of the auxiliary ring and the inner wall of the housing, thereby preventing the auxiliary ring from changing arbitrarily when the gear pump is working. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Figure 1 2 is a schematic structural diagram of a non-oil trapped gear pump according to an embodiment of the present invention;

[0022] Figure 2 is a front view of the cooperation between the driving gear and the driven gear in the embodiment of the present invention;

[0023] Figure 3 yes Figure 2 Middle AA structure section view;

[0024] Figure 4 is an axonometric diagram of the cooperation between the driving gear and the driven gear in an embodiment of the present invention;

[0025] Figure 5 is a schematic diagram of the axonometric structure of a housing in an embodiment of the present invention;

[0026] Figure 6 is a schematic structural diagram of a cover plate in an embodiment of the present invention;

[0027] Figure 7 Schematic diagram of the structure of the auxiliary ring in the embodiment of the present invention.

[0028] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0029] Wherein: 1. housing, 2. driving gear, 3. driven gear, 4. auxiliary ring, 5. second segment, 6. first segment, 7. cover plate, 8. limiting structure, 11. inner wall of housing, 41. groove. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] Glossary:

[0032] Oil trapping phenomenon: During the working process of the gear pump, due to the design of the overlap coefficient of the gear being greater than 1, a part of the oil is trapped in the closed oil chamber formed by the two pairs of gears during the period when the two pairs of gear teeth are meshing at the same time. The volume of this closed oil chamber will change with the rotation of the gears. When the volume decreases, the oil is squeezed, which may lead to increased pressure and temperature; when the volume increases, a local vacuum may be formed, resulting in cavitation, which causes vibration and noise.

[0033] Unloading groove: A structural feature used to alleviate oil entrapment by allowing the trapped oil chamber to communicate with the high pressure chamber or the low pressure chamber, thereby reducing the fluctuations in trapped oil pressure and the associated negative effects.

[0034] Cavitation: Also known as cavitation, it refers to the rapid precipitation of gas or vapor in a liquid and the formation of bubbles when the local pressure in the liquid drops to the saturated vapor pressure of the liquid or lower. These bubbles then collapse rapidly when the liquid pressure is restored. This process is accompanied by a violent release of energy, which may cause a local temperature increase and a sharp change in pressure in the liquid.

[0035] Embodiment 1

[0036] In a typical embodiment of the present invention, reference is made to Figure 1-Figure 7 As shown, an oil-free gear pump includes a housing 1, a driving gear 2, a driven gear 3, an auxiliary ring 4 and a cover plate 7. Two gear grooves are provided in the housing 1, which are used to install the driving gear 2 and the driven gear 3 respectively. The auxiliary ring is installed between the gear and the inner wall 11 of the housing, and has the functions of supporting, sealing and pressure balancing.

[0037] The driving gear and the driven gear mesh with each other inside the housing. The driving gear and the driven gear are located between the oil inlet and outlet passages of the housing. After the driving gear 2 and the driven gear 3 are installed on the housing, the cover plate 7 can be installed. The cover plate 7 is provided with shaft grooves that cooperate with the two gears. In this embodiment, two cover plates 7 are provided, which are located on both sides of the gear.

[0038] like Figure 1 and Figure 5 As shown, the two gear grooves are arranged in a circular shape with openings in opposite directions, and the inner diameter is adapted to the outer diameter of the gear. In order to solve the oil trapping phenomenon, the gear tooth ends of the driving gear 2 and the driven gear 3 are turned to a set length to form a first segment 6, and the unturned part is the second segment 5.

[0039] like Figure 3 and Figure 4 As shown, the gear tooth end of each gear is turned from both sides to the middle position to set the length, so that the gear tooth end has two height sections, namely a lower first section 6 and a higher second section 5.

[0040] It can be understood that the segment positions on the driving gear 2 and the driven gear 3 are the same, and the first segment 6 and the second segment 5 are symmetrical about the middle position at the ends of the gear teeth. After the driving gear 2 and the driven gear 3 are installed, the overlapping coefficient of the first segment on the gear teeth of the driving gear 2 and the driven gear 3 is equal to 1, and the overlapping coefficient of the second segment 5 is greater than 1, so that when the gear teeth of the second segment 5 enter the meshing state, the gear teeth of the first segment 6 do not enter the meshing state. Therefore, when the gear pump is working, when the second segment 5 starts to mesh, the oil at the second segment 5 flows out from the first segments 6 on both sides. When the two groups of first segments 6 enter the meshing, the three segments have all left the oil trapped area, thereby effectively avoiding the occurrence of oil trapped.

[0041] It can be understood that the first segment of the present embodiment is a planar structure with a uniform width and a rectangular shape, which is convenient for turning, has high processing efficiency and a simple processing process.

[0042] Since the first segment 6 is machined on the end of the gear teeth on the driving gear 2 and the driven gear 3, there is a gap between the first segment 6 on the end of the gear teeth and the inner wall 11 of the shell. In order to effectively support the gears and ensure the sealing, an auxiliary ring 4 for sealing and support is installed between the driving gear 2 and the driven gear 3 and the inner wall 11 of the shell. The outer side surface of the auxiliary ring 4 is in close contact with the inner wall 11 of the shell, and the inner side surface is in contact with the end of the first segment 6 on the end of the gear teeth.

[0043] It can be understood that the width of the auxiliary ring 4 is adapted to the turning length of the first segment 6 so as to fully make up for the gap between the first segment 6 and the inner wall 11 of the housing.

[0044] In order to prevent the auxiliary ring 4 from changing its position during the operation of the gear pump, it is necessary to fix the position of the auxiliary ring 4 after it is installed on the inner wall 11 of the housing.

[0045] Specifically, a limiting structure 8 is provided at the inner wall 11 of the shell, which is used to limit the auxiliary ring 4 so that the auxiliary ring 4 is relatively fixed to the inner wall 11 of the shell. Figure 1 As shown, the shape of the auxiliary ring 4 is adapted to the shape of the inner wall 11 of the shell, and both are open circular structures. Limit blocks are set at the steps of the inner wall of the shell at the oil inlet and outlet channels. The limit blocks protrude toward the inside of the shell and are used to abut the end of the auxiliary ring 4. The thickness of the limit block is smaller than that of the auxiliary ring 4, ensuring that the limit block will not affect the normal rotation of the gear.

[0046] In another example, a card slot is provided on the inner wall 11 of the shell, and an opening is provided on the auxiliary ring 4. After the auxiliary ring 4 is installed, the position of the opening is set corresponding to the position of the card slot, and a positioning pin is passed through the opening and stuck in the card slot to achieve relative fixation between the auxiliary ring 4 and the inner wall 11 of the shell.

[0047] like Figure 1 and Figure 7As shown, a groove 41 is provided in the middle of the side edge of the auxiliary ring 4, and the grooves 41 on the two auxiliary rings 4 are arranged on the side away from each other, and are symmetrically arranged to achieve pressure equalization.

[0048] The gear end of this embodiment is divided into three groups of segments, wherein the second segment 5 is located in the middle of the gear, and the two ends of the second segment 5 are the first segment 6, making gear processing more convenient, and only a part of the upper and lower segments need to be turned off, which reduces the processing difficulty. At the same time, the use of the side plate is eliminated, and there is no need to install the side plate structure with the unloading groove, which saves the manufacturing cost of the gear pump. At the same time, since there is no need to install the side plate, the overall axial volume of the gear pump is smaller.

[0049] In order to ensure the transmission efficiency of the gear pump, the length of the second segment is twice the length of the first segment, and the second segment mainly plays the role of a unloading groove.

[0050] In another preferred example, the ends of the gear teeth of the driving gear 2 and the driven gear 3 are divided into three groups of segments, wherein the first segment 6 is located in the middle of the gear teeth, the two ends of the first segment 6 are the second segments 5, and the length of the first segment is one third of the length of the gear teeth, so the lengths of a group of first segments 6 and a group of second segments 5 are equal.

[0051] It should be noted that, in other examples, the specific length parameters of the first segment and the second segment are not limited to the above two parameter standards, and can be determined according to the overall parameters of the gear pump to achieve the optimal working efficiency of the gear pump.

[0052] In this example, due to the middle position of the lower first segment 6, when installing the auxiliary ring 4, it is necessary to first use a rolling device to roll the auxiliary ring into a ring shape, and then clamp it on the first segment 6 on the outside of the gear tooth end as a set of integral structures. After that, the integral structure is installed in the gear groove of the inner wall 11 of the shell. The gear pump of this structural form can also solve the oil trapping problem. When processing this structure, a part of the middle position of the gear tooth end can be turned to obtain the desired structure.

[0053] As for the positioning form of the auxiliary ring 4, a limit block form or a form of matching a slot and a positioning pin may be considered, and the specific selection can be made according to needs.

[0054] In order to achieve the pressure equalization effect, grooves are provided in the middle of the two side edges of the auxiliary ring 4, and the structure of a single auxiliary ring 4 is symmetrical to ensure the pressure equalization effect.

[0055] Since the auxiliary ring 4 of this structural form needs to be fitted on the outer side of the first segment 6 and then installed into the shell as a whole during installation, an additional rolling step is required. Therefore, a structural form in which the second segment 5 is opened in the middle of the gear teeth is preferred.

[0056] For the structure in the middle of the gear teeth, when installing, first install the auxiliary ring 4 on the same side of the first group, then install the two gears, and finally install the auxiliary ring 4 on the other side, and finally install the cover plate 7 on the open side.

[0057] When the overlap coefficient of the gear pump is greater than 1, oil trapping can effectively prevent vibration, but it will cause oil trapping. On the contrary, when the overlap coefficient of the gear pump is less than 1, oil trapping can cause vibration, but it will not cause oil trapping. Therefore, the gear is segmented, and a part of the upper and lower sections is turned off, so that the top circle of the upper and lower sections is reduced, and the overlap coefficient of this part is also reduced accordingly. Therefore, the middle section (second section 5) can prevent vibration, and the upper and lower sections can avoid oil trapping. Turning only requires a little more processing on the upper and lower sections when processing the top circle, and the processing process is simple.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An oil-free gear pump, characterized in that: The invention comprises a housing (1), wherein a driving gear (2) and a driven gear (3) meshing with each other are arranged in the housing (1), the gear teeth ends of the driving gear (2) and the driven gear (3) are turned to a set length to form a first segment (6), and the unturned portion is a second segment (5), the segments on the driving gear (2) and the driven gear (3) are in the same position, and the first segment (6) and the second segment (5) are symmetrical about the middle position at the gear teeth ends; the overlap coefficient of the first segment (6) on the gear teeth of the driving gear (2) and the driven gear (3) is equal to 1, and the overlap coefficient of the second segment (5) is greater than 1, so that when the gear teeth of the second segment (5) enter a meshing state, the gear teeth of the first segment (6) do not enter a meshing state.

2. The oil-free gear pump according to claim 1, characterized in that: An auxiliary ring (4) for sealing and supporting is installed between the driving gear (2) and the driven gear (3) and the inner wall (11) of the housing. The outer side surface of the auxiliary ring (4) is in close contact with the inner wall (11) of the housing, and the inner side surface is in close contact with the end of the first segment (5) of the gear tooth end.

3. The oil-free gear pump according to claim 2, characterized in that: A limiting structure (8) is provided on the inner wall of the shell, which is used to limit the auxiliary ring (4) so ​​that the auxiliary ring (4) and the inner wall (11) of the shell are relatively fixed.

4. The oil-free gear pump according to claim 1, characterized in that: The first segment (6) is a planar structure with a uniform width.

5. The oil-free gear pump according to claim 4, characterized in that: The width of the auxiliary ring (4) is adapted to the turning length of the first segment (6).

6. The oil-free gear pump according to claim 5, characterized in that: A groove (41) is provided on the side edge of the auxiliary ring (4) for achieving pressure equalization.

7. The oil-free gear pump according to claim 1, characterized in that: The end of the gear tooth is divided into three groups of segments, wherein the second segment (5) is arranged in the middle of the gear tooth, and the two ends of the second segment (5) are the first segments (6).

8. The oil-free gear pump according to claim 7, characterized in that: The length of the second segment (5) is twice the length of the first segment (6).

9. The oil-free gear pump according to claim 1, characterized in that: The end of the gear tooth is divided into three groups of segments, wherein the first segment (6) is arranged in the middle of the gear tooth, and the two ends of the first segment (6) are the second segments (5).

10. The oil-free gear pump according to claim 9, characterized in that: The length of the first segment (6) is one third of the length of the gear tooth.

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