Hydraulic gear pump

Abstract

The utility model provides a hydraulic gear pump which comprises oppositely arranged pump bodies, main gears arranged in inner cavities of the pump bodies, a front end cover and a rear end cover which are arranged at the two ends of the pump bodies, and further comprises connecting plates arranged on the butt joint faces of the pump bodies, and the connecting plates connected between the pump bodies are fixedly connected in a sealed mode; the internal connection mode of the gear pump is that the involute spline shaft is connected with the main gears on the two sides, and the spline shaft can be designed to be small and compact and is light in weight under the condition of the same transmission load; the involute spline pair has an automatic centering function, the defect that a flat key and a cross joint cannot be self-centered is overcome, after the spline teeth of the spline pair are stressed, the inner spline and the outer spline can automatically coincide, tooth surfaces are in sliding fit to enter a contact state, in the torque transmission process, backlash in the tooth height normal direction is equal, most of the spline teeth can be in contact at the same time, and the service life of the spline pair is prolonged. Multiple teeth are used for bearing, so that the impact force is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of double-connected hydraulic gear pumps in hydraulic systems, and particularly relates to a hydraulic gear pump with the characteristics of compact structure, light weight and non-oil mixing in both directions. Background Art

[0002] The hydraulic gear pump is an important component of a hydraulic system. It has the characteristics of simple structure, small volume, light weight and insensitivity to oil pollution, and is widely used in hydraulic systems in the fields of light industry, agricultural machinery, construction machinery and the like. In recent years, the hydraulic system has been gradually developing in the direction of rapid response, intelligence and safety, which requires that the hydraulic gear pump has the characteristics of high pressure resistance and impact resistance, as well as compact structure and reliable sealing.

[0003] The gear pump is generally arranged at the PTO port of the engine. Because the working media of the front pump and the rear pump are different, the seals between levels need to have high reliability. At the same time, an oil level gauge is provided at the proximal end of the axial tail of the gear pump, so the installation space is limited. Therefore, the gear pump is required to be able to adapt to different media, have a compact structure, be light in weight and have the characteristic of non-oil mixing in both directions. The traditional internal connection method of the gear pump mostly uses the structure combined with "flat key and cross joint" or "spline sleeve and positioning sleeve". Refer to Figure 1 , Figure 1 In the traditional gear pump shown in, the structure of combining the spline sleeve 5 and the positioning sleeve 6 is adopted. Because the meshing length of the spline pair is short, when the system load pressure increases, it is necessary to increase the axial length of the spline sleeve 5 and the positioning sleeve 6, thus increasing the total axial length of the gear pump. Therefore, the traditional internal connection method of the gear pump cannot adapt to the occasions with high load and heavy-duty transmission requirements of the hydraulic system. At the same time, the traditional sealing design idea of the gear pump is to use a single rotating skeleton oil seal for sealing, which has the problem of low sealing reliability. At the same time, the pump bodies of the gear pump are axially connected by using a multi-stage split connecting plate. When the number of connecting plates is large, it will cause the total axial dimension of the gear pump to be long and heavy. Summary of the Utility Model

[0004] The utility model provides a hydraulic gear pump, which can meet the torque transmission requirements under different load conditions. When the system load pressure increases, only the meshing length of the spline pair of the spline shaft needs to be increased, and there is no need to increase the total axial length of the gear pump. At the same time, the utility model can also reduce the number of connecting plates and thin the thickness of the connecting plates, and further reduce the self-weight of the gear pump under the condition of meeting the system working conditions.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] A hydraulic gear pump includes pump bodies arranged oppositely, a main gear arranged in the inner cavity of the pump body, and a front end cover and a rear end cover arranged at both ends of the pump body, and further includes:

[0007] A connecting plate is arranged on the butt joint surface of the pump body, and the connecting plates between the connected pump bodies are hermetically fixed together.

[0008] A spline shaft penetrates through the connecting plates of the connected pump bodies, and both ends of the spline shaft are respectively connected to the main gears in the two side pump bodies; and

[0009] A positioning pin is arranged along the circumferential direction of the pump body, and both ends of the positioning pin penetrate through the connecting plates of the connected pump bodies and extend into the interior of the pump body.

[0010] Preferably, the spline shaft is made of high hardenability carburizing steel and is subjected to carburizing and quenching treatment, and the spline shaft is arranged inside the main shaft and the main gear.

[0011] Preferably, a main shaft for installing the main gear is arranged inside the pump body, one end of the main shaft close to the connecting plate extends into the connecting plate of the pump body where the main shaft is located, and both ends of the spline shaft are respectively connected to the end parts of the main shafts in the two side pump bodies.

[0012] Preferably, external splines are arranged at both ends of the spline shaft, and internal splines matching the external splines are arranged at the end parts of the main shaft close to the connecting plate.

[0013] Preferably, an installation groove is formed at one end of the connecting plate away from the pump body, and a first skeleton oil seal is arranged between the shaft side of the main shaft placed in the installation groove and the inner wall of the installation groove.

[0014] Preferably, the front end cover and the rear end cover are fixedly connected to the pump body by screws.

[0015] Preferably, the main shaft on the side of the front end cover penetrates through the front end cover, and a second skeleton oil seal is arranged between the shaft side of the main shaft and the inner wall of the front end cover.

[0016] From the above technical solutions, the present utility model has the following beneficial effects:

[0017] 1. In the present utility model, the internal connection mode of the gear pump adopts an involute spline shaft to connect with the two side main gears. Under the condition of the same transmitted load, the spline shaft can be designed to be small and compact, and has a light weight; the involute spline pair has the function of automatic centering, making up for the disadvantages that the flat key and the cross joint cannot self-center. After the key teeth of the spline pair are stressed, the internal spline and the external spline can automatically coincide, and the tooth surfaces slide into the contact state. During the process of transmitting torque, the normal side clearance along the tooth height is equal, enabling most key teeth to be in contact at the same time, bearing through multiple teeth, and reducing the impact force.

[0018] 2. In the present utility model, a connecting plate is provided on the docking surface of the pump body. The ends of the two main shafts are placed in the installation grooves, and the sealing of the main shafts is achieved through the first skeleton oil seal. The gear pump of the present utility model only needs to use two connecting plates to arrange two first skeleton oil seals, achieving a two-way sealing arrangement, ensuring that the gear pump does not have oil leakage in both directions, and having the advantage of high reliability. Brief Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of a traditional gear pump;

[0020] Figure 2 is a schematic structural diagram of the hydraulic gear pump provided by the present utility model.

[0021] In the figure: 1, connecting plate one; 2, connecting plate two; 3, connecting plate three; 4, skeleton oil seal; 5, spline sleeve; 6, positioning sleeve; 7, front cover; 8, rear cover; 9-1, front main gear; 9-2, rear main gear; 10, pump body; 110, main shaft; 120, screw; 20, main gear; 30, front end cover; 40, rear end cover; 50, connecting plate; 60, spline shaft; 70, positioning pin; 80, first skeleton oil seal; 90, second skeleton oil seal. Detailed Embodiment

[0022] The following is a detailed description of a preferred embodiment of the present utility model with reference to the drawings.

[0023] The structural schematic diagram of the traditional gear pump is as Figure 1 shown. In the figure, reference numerals 1, 2, and 3 are all connecting plates. For the convenience of distinction, reference numeral 1 can be named connecting plate one, reference numeral 2 can be named connecting plate two, reference numeral 3 can be named connecting plate three, reference numeral 4 is the skeleton oil seal, reference numeral 5 is the spline sleeve, reference numeral 6 is the positioning sleeve, reference numeral 7 is the front cover, reference numeral 8 is the rear cover, reference numeral 9-1 is the front main gear, and reference numeral 9-2 is the rear main gear.

[0024] To achieve the purpose of the present utility model, the embodiments of the present utility model adopt the following technical solutions: Refer to Figure 2, A hydraulic gear pump, comprising a pump body 10 arranged oppositely, a main gear 20 arranged in the inner cavity of the pump body, a front end cover 30 and a rear end cover 40 arranged at both ends of the pump body, further comprising a connecting plate 50, a spline shaft 60 and a positioning pin 70. The connecting plate is arranged on the butt joint surface of the pump body 10, and the connecting plates between the connected pump bodies are hermetically fixed. The spline shaft penetrates through the connecting plates of the connected pump bodies 10, and both ends of the spline shaft are respectively connected with the main gears 20 in the pump bodies on both sides. The positioning pin is arranged along the circumferential direction of the pump body, and both ends of the positioning pin penetrate through the connecting plates 50 of the connected pump bodies 10 and extend into the pump body. The internal connection mode of the present utility model uses an involute spline shaft to connect with the main gears on both sides. Under the condition of the same transmitted load, the spline shaft can be designed to be small and compact, and has a light weight; the involute spline pair has the function of automatic centering, making up for the disadvantage that the flat key and the cross joint cannot self-center. After the key teeth of the spline pair are stressed, the internal spline and the external spline can automatically coincide, and the tooth surfaces slide into the contact state. During the process of transmitting torque, the normal side clearance along the tooth height is equal, enabling most key teeth to be in contact simultaneously, and bearing through multiple teeth to reduce the impact force;

[0025] In the traditional structure of the spline sleeve cooperating with the positioning sleeve, because the engagement length of the spline pair is short, when the system load pressure increases, it is necessary to increase the axial length of the spline sleeve and the positioning sleeve, thereby increasing the total axial length of the gear pump. The internal connection mode of the present utility model can meet the torque transmission requirements under different load conditions. When the system load pressure increases, only the engagement length of the spline pair of the spline shaft needs to be increased, and there is no need to increase the total axial length of the gear pump.

[0026] Furthermore, the positioning pin 70 adopts a rigid long pin, which is not only convenient for installation, but also improves the accuracy and stability of product positioning.

[0027] Furthermore, the front end cover and the rear end cover of the traditional gear pump use gray cast iron material, and the outer surface of the parts needs to be sprayed with paint and dried, with a long process and being not environmentally friendly. The front end cover 30, the rear end cover 40 and other components of the gear pump of the present utility model all use cast aluminum alloy material, which not only reduces the process flow, but also reduces the self-weight of the gear pump; meanwhile, the front end cover 30 and the rear end cover 40 are fixedly connected with the pump body 10 through screws 120.

[0028] Furthermore, in this embodiment, the axial length of the main gear in the pump body can be further shortened to reduce the influence of heat treatment deformation and machining deformation on the volumetric efficiency of the gear pump.

[0029] As the preferred technical solution of this embodiment, the spline shaft 60 adopts high hardenability carburizing steel and is subjected to carburizing and quenching treatment to improve the comprehensive mechanical properties of the spline shaft; the spline shaft 60 is arranged inside the main shaft 110 and the main gear 20, greatly saving the axial installation space and also reducing the number of installation parts.

[0030] As a preferred technical solution of this embodiment, in order to facilitate the installation of the main gear 20 inside the pump body 10, a main shaft 110 is provided inside the pump body 10. The presence of the main shaft facilitates the rotation of the main gear inside the pump body. Further, one end of the main shaft close to the connecting plate 50 extends into the connecting plate inside the pump body where the main shaft is located. At the same time, both ends of the spline shaft 60 are respectively connected to the end parts of the main shafts inside the pump bodies on both sides. It should be noted that for each pump body on one side, the main shaft inside it penetrates the connecting plate on this side but does not penetrate the connecting plate on the adjacent side. In this way, there is a gap between the main shafts on both sides, and the spline shaft connects the main shafts on both sides through the above-mentioned gap.

[0031] Further, external splines are provided at both ends of the spline shaft 60, and internal splines matching the external splines are provided at the end part of the main shaft 110 close to the connecting plate. During use, the external splines on the spline shaft can automatically coincide with the internal splines on the main shaft and enter the contact state through sliding engagement of the tooth surfaces.

[0032] Further, an installation groove is formed at one end of the connecting plate 50 away from the pump body 10. A first skeleton oil seal 80 is provided between the shaft side of the main shaft 110 placed in the installation groove and the inner wall of the installation groove. In this way, when the mounting plates on both sides of the pump body are butted, the installation grooves on them are arranged oppositely. The end parts of the main shafts on both sides are placed in the installation grooves, and the main shaft is sealed through the first skeleton oil seal. It should be noted that only two connecting plates are required for the gear pump in this embodiment to arrange two first skeleton oil seals, realizing the arrangement of double-sided sealing, ensuring that the gear pump does not have oil leakage in both directions, and having the advantage of high reliability.

[0033] At the same time, three connecting plates are required inside the traditional gear pump, which will cause the gear pump to have a long axial dimension and heavy weight. At the same time, only one skeleton oil seal can be arranged inside, resulting in the problem of low sealing reliability. Compared with the internal connection structure of the traditional gear pump that requires three connecting plates, the number of connecting plates in this embodiment is reduced, and at the same time, the thickness of the connecting plate is also reduced. Under the condition of meeting the system working conditions, the thickness and weight of a single connecting plate are both reduced, further reducing the self-weight of the gear pump.

[0034] As a preferred technical solution of this embodiment, the main shaft 110 on the side of the front end cover 30 penetrates the front end cover, and a second skeleton oil seal 90 is provided between the shaft side of the main shaft and the inner wall of the front end cover. Among them, the number of the second skeleton oil seals is two. By arranging two skeleton oil seals inside the front end cover and choosing to press-fit them in a positive and negative manner, it can not only prevent the external leakage of the hydraulic oil inside the gear pump, but also prevent the internal leakage of external grease and other media, further improving the sealing reliability of the gear pump.

[0035] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A hydraulic gear pump, comprising a pump body (10) arranged opposite to each other, a main gear (20) arranged in the inner cavity of the pump body, and a front cover (30) and a rear cover (40) arranged at both ends of the pump body, characterized in that: Also includes: A connecting plate (50), the connecting plate being arranged on the butt joint surface of the pump body (10) and the connecting plate connecting the pump bodies is sealed and fixedly connected; A spline shaft (60), the spline shaft passing through a connecting plate of a connected pump body (10), and the two ends of the spline shaft are respectively connected to the main gears (20) in the pump bodies at both sides; and A positioning pin (70) is arranged along the circumference of the pump body, and both ends of the positioning pin penetrate through a connecting plate (50) connected to the pump body (10) and extend into the interior of the pump body.

2. The hydraulic gear pump according to claim 1, characterized in that: The spline shaft (60) is made of high-hardenability carburizing steel and is carburized and quenched. The spline shaft (60) is arranged inside the main shaft (110) and the main gear (20).

3. The hydraulic gear pump according to claim 1, characterized in that: A main shaft (110) for mounting a main gear (20) is provided inside the pump body (10), and one end of the main shaft close to the connecting plate (50) extends to the inside of the connecting plate of the pump body where the main shaft is located, and both ends of the spline shaft (60) are respectively connected to the ends of the main shaft in the pump bodies on both sides.

4. The hydraulic gear pump according to claim 3, characterized in that: External splines are provided at both ends of the spline shaft (60), and internal splines matching the external splines are provided at the end of the main shaft (110) close to the connecting plate.

5. The hydraulic gear pump according to claim 3, characterized in that: An installation groove is formed at one end of the connecting plate (50) away from the pump body (10), and a first skeleton oil seal (80) is provided between the shaft side of the main shaft (110) placed in the installation groove and the inner wall of the installation groove.

6. The hydraulic gear pump according to claim 1, characterized in that: The front end cover (30) and the rear end cover (40) are fixedly connected to the pump body (10) by means of screws (120).

7. The hydraulic gear pump according to claim 1, characterized in that: The main shaft (110) on the front end cover (30) side is arranged to penetrate the front end cover, and a second skeleton oil seal (90) is arranged between the main shaft side and the inner wall of the front end cover.

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