A sleeve for improving the low speed and heavy load operation of a gear pump

Abstract

The application belongs to the technical field of hydraulic components and systems, and discloses a shaft sleeve for reducing the minimum stable working rotating speed of a gear pump, which comprises a driving wheel shaft sleeve and a driven wheel shaft sleeve, a static pressure bearing and a dynamic pressure bearing; the static pressure bearing is installed inside the connecting body and comprises a static pressure pipeline and a plurality of static pressure oil holes which are uniformly distributed on the inner wall of the shaft sleeve; the static pressure oil holes and the static pressure pipeline are connected in the horizontal direction, and the inlet of the static pressure pipeline is communicated with the outlet of the external gear pump; the dynamic pressure bearing comprises a plurality of dynamic pressure oil grooves which are arranged on the inner wall of the shaft sleeve from top to bottom and are parallel and spaced from each other, and the top end of the dynamic pressure oil groove is communicated with the outlet of the external gear pump. The dynamic pressure bearing and the static pressure bearing are introduced into the shaft sleeve at the same time, a stable load oil film is formed at the low rotating speed stage, dry friction and early wear are effectively avoided, and the bearing supporting capacity can be further enhanced by using the dynamic pressure effect at the heavy load stage.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic components and systems technology, and more specifically, relates to a bushing for improving the low-speed and heavy-load operation of a gear pump. Background Technology

[0002] Gear pumps are a type of positive displacement hydraulic pump widely used in hydraulic systems. They rely on the periodic change of the closed working volume formed between the pump body and meshing gears during rotation to achieve the intake and discharge of liquid, thereby completing the liquid transportation and pressurization. A gear pump typically consists of a pair of meshing gears, a gear shaft, a pump body, end covers, flanges, and bearings. These pumps are compact, simple to manufacture, low in cost, operate smoothly and reliably, provide continuous flow output, and are highly adaptable to working media, making them widely used in hydraulic systems in industry, transportation, and aviation.

[0003] However, gear pumps also have some significant technical drawbacks, such as high internal leakage rates, large operating noise and pressure pulsation, severe oil trapping, and vibration and efficiency reduction due to uneven load distribution. Among these, wear on gears and bearings is one of the main causes of performance degradation and failure. Statistics show that radial sliding bearing failures account for approximately 45% of the overall gear pump failure rate, making it a key factor affecting its reliability and lifespan. During low-speed or load-bearing startup, due to insufficient relative shaft speed, the hydrodynamic oil film has not yet been established or is unstable, resulting in a significant decrease in lubrication performance. This easily leads to direct contact between the journal and bushing, causing boundary friction, localized overheating, accelerated wear, and even premature bearing failure. Under high pressure or variable load conditions, these problems are particularly pronounced and are a major factor limiting the low-speed operation capability and reliability of gear pumps.

[0004] In contrast, hydrostatic lubricated sliding bearings introduce oil directly into the bearing clearance through an external high-pressure oil supply system, establishing a stable oil film even without relative motion. This makes them suitable for low-speed, heavy-load, or frequent start-stop conditions. However, hydrostatic bearings have a complex structure, requiring an independent oil supply system and throttling device. This makes system integration difficult and costly, limiting their application in compact gear pumps.

[0005] Both of the above lubrication methods have their advantages. Static pressure provides initial support during the low-speed or startup phase of the gear pump, while hydrodynamic pressure takes over the load-bearing capacity as the speed increases, achieving full-condition coverage of lubrication performance. If a hybrid hydrodynamic-static lubrication structure can be rationally integrated into the gear pump bushing, it can not only significantly improve the problem of insufficient lubrication at low speeds, but also effectively enhance the starting capability and operational stability of the gear pump under complex conditions such as heavy loads and frequent start-stop cycles, which is of great significance for improving its service life and system reliability. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a bushing for improving the low-speed and heavy-load operation of gear pumps, thereby solving the technical problems of insufficient lubrication and easy bearing wear under low-speed and heavy-load conditions. This invention introduces high-pressure oil into the bearing clearance of the gear pump to form a hydrostatic support, providing stable load-bearing capacity during startup and low-speed phases, avoiding dry friction and premature wear. During rated speed operation, as the gear shaft rotates, the hydrodynamic effect gradually increases, further enhancing the oil film load-bearing capacity and system stability. This method eliminates the need for an external independent oil supply device, and the bushing structure is highly integrated, making it suitable for the stable operation of gear pumps under complex conditions such as low speed, heavy load, and frequent start-stop. It can significantly improve low-speed load-bearing capacity, reduce the minimum stable speed, improve lubrication, extend bearing life, and enhance the overall operating efficiency and reliability of the machine.

[0007] To achieve the above objectives, according to one aspect of the present invention, a bushing for reducing the minimum stable operating speed of a gear pump is provided, the bushing comprising a driving wheel bushing, a driven wheel bushing, a hydrostatic support, and a hydrodynamic support;

[0008] The driving wheel bushing and the driven wheel bushing are connected by a connecting body and are symmetrically arranged about the connecting body; the hydrostatic support is installed inside the connecting body; the hydrostatic support includes a hydrostatic pipeline and a plurality of hydrostatic oil holes; the hydrostatic oil holes are connected to the hydrostatic pipeline; the hydrostatic pipeline is located inside the connecting body, and the hydrostatic oil holes are evenly distributed on the inner walls of the driving wheel bushing and the driven wheel bushing; the inlet of the hydrostatic pipeline is connected to the shaft hole of the gear pump;

[0009] The hydrodynamic support includes a plurality of hydrodynamic oil grooves; the hydrodynamic oil grooves are located on the inner wall surfaces of the driving wheel bushing and the driven wheel bushing, and each hydrodynamic oil groove is arranged in parallel intervals with each other.

[0010] Preferably, the hydrostatic oil hole opened on the inner wall of the drive wheel bushing is called the drive wheel hydrostatic oil hole, and the hydrostatic oil hole opened on the inner wall of the driven wheel bushing is called the driven wheel hydrostatic oil hole; the drive wheel hydrostatic oil hole and the driven wheel hydrostatic oil hole are both located on the side close to the connecting body, and are symmetrically arranged with respect to the connecting body.

[0011] Preferably, the static pressure pipeline includes a straight static pressure pipeline, an E-type static pressure pipeline bend, and several rows of horizontal static pressure pipelines arranged parallel to each other vertically; the E-type static pressure pipeline bend includes a main pipeline and several branch pipelines; one end of each branch pipeline is connected to the main pipeline, and the branch pipelines are arranged parallel to each other at intervals; the straight static pressure pipeline is connected to the main pipeline, and the end of each branch pipeline away from the main pipeline is connected to the middle of the horizontal static pressure pipeline; the two ends of the horizontal static pressure pipeline are respectively connected to the static pressure oil hole of the driving wheel and the static pressure oil hole of the driven wheel.

[0012] Preferably, the dynamic pressure oil groove includes 3 to 5 driving wheel dynamic pressure oil grooves and 3 to 5 driven wheel dynamic pressure oil grooves; adjacent driving wheel dynamic pressure oil grooves are arranged at 90° intervals on the inner wall surface of the driving wheel bushing, and adjacent driven wheel dynamic pressure oil grooves are arranged at 90° intervals on the inner wall surface of the driven wheel bushing.

[0013] Preferably, the top end face of the connecting body is provided with a first unloading groove, and the end faces of the top inner circumference of the driving wheel bushing and the driven wheel bushing are both provided with annular grooves. The bottom of the annular groove is connected to the top of the dynamic pressure oil groove. The annular groove and the first unloading groove are connected by a horizontal diversion groove, which is used to introduce the oil in the gear pump into the annular groove and the dynamic pressure oil groove.

[0014] Preferably, the top end face of the connector is further provided with a second unloading groove that is symmetrical to the first unloading groove.

[0015] Preferably, a sealing groove is formed on the bottom end face of the bushing, and a sealing element is filled in the sealing groove. The inner ring of the sealing element forms a low-pressure balance zone with the bottom of the bushing and the bottom end cap of the bushing, and a high-pressure balance zone is formed between the outer ring of the sealing element and the bottom of the bushing and the bottom end cap of the bushing. The high-pressure balance zone is connected to the high-pressure oil chamber of the gear pump through a high-pressure flow hole, and the low-pressure balance zone is connected to the low-pressure oil chamber of an external gear pump through a low-pressure flow hole.

[0016] Preferably, both the top outer circumferential end face edges of the driving wheel bushing and the driven wheel bushing are provided with flow grooves.

[0017] Preferably, the drive wheel bushing is sleeved on the drive shaft of the gear pump, so that the inner wall of the drive wheel bushing is indirectly in contact with the drive shaft through the oil flowing through the drive wheel dynamic pressure oil groove and the drive wheel static pressure oil hole; the driven wheel bushing is sleeved on the driven shaft of the gear pump, so that the inner wall of the driven wheel bushing is indirectly in contact with the driven shaft through the oil flowing through the driven wheel dynamic pressure oil groove and the driven wheel static pressure oil hole.

[0018] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0019] 1. The bushing of the present invention introduces both dynamic and static pressure supports in the bushing, enabling the gear pump to form a stable bearing oil film at low speed or during the start-up phase, effectively avoiding dry friction and early wear. During the rated speed operation phase, the dynamic pressure effect can be used to further enhance the bearing support capacity. At the same time, this structure does not require an additional external oil supply system, has a high degree of system integration, and is simple and reliable in structure.

[0020] 2. This invention defines the specific structure of the static pressure support and the dynamic pressure support. Through the synergistic effect of the static pressure support and the dynamic pressure support, the eccentric movement of the gear shaft can be effectively reduced, the axial force and radial force inside the gear pump can be balanced, vibration and noise can be reduced, and the stability and service life of the pump body can be further improved.

[0021] 3. The flow channel provided by the present invention can extend the high-pressure area in the gear pump to the low-pressure side, further expanding the coverage of the high-pressure area and improving the sealing state between the gear pump tooth clearance volume and the gear pump casing, thereby significantly suppressing radial leakage of the gear pump. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the bushing of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of the upper end face of the bushing of the present invention.

[0024] Figure 3 This is a schematic diagram of the structure of the lower end face of the bushing of the present invention.

[0025] Figure 4 This is a cross-sectional schematic diagram of the bushing static pressure pipeline of the present invention.

[0026] Figure 5 This is an overall schematic diagram of the bushing static pressure pipeline of the present invention.

[0027] Figure 6 This is a schematic diagram illustrating the working principle of the bushing of the present invention.

[0028] Figure 7 This is a schematic diagram of the bushing of the present invention being combined with the gear pump.

[0029] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1—static pressure oil hole; 2—static pressure pipeline; 3—dynamic pressure oil groove; 4—second unloading groove; 5—flow groove; 6—annular groove; 7—drainage groove; 8—first unloading groove; 9—sealing ring groove; 10—gear pump; 11—shaft sleeve; 12—drive shaft; 13—driven shaft; 14—shaft hole; 1-1—static pressure oil hole of drive wheel; 1-2—static pressure oil hole of driven wheel; 2-1—straight pipe of static pressure pipeline; 2-2—E-type static pressure pipeline bend; 2-3—horizontal pipe of static pressure pipeline; 3-1—dynamic pressure oil groove of drive wheel; 3-2—dynamic pressure oil groove of driven wheel; 11-1—drive wheel shaft sleeve; 11-2—driven wheel shaft sleeve; 11-3—connecting body. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Example 1

[0032] This invention provides a bushing 11 for improving the low-speed and heavy-load operation of a gear pump, such as... Figure 1 , Figure 4 and Figure 5 As shown, the bushing 11 is a symmetrical, integrated design. The driving wheel bushing 11-1 and the driven wheel bushing 11-2 are connected by a connector 11-3. Both the driving wheel bushing 11-1 and the driven wheel bushing 11-2 have an array of 15 hydrostatic oil holes 1 and 3 dynamic oil grooves 3 on their inner walls. Within the same bushing, adjacent dynamic oil grooves 3 are arranged parallel and spaced 90° apart. The 15 hydrostatic oil holes 1 are all located on the inner wall of the bushing closest to the connector 11-3, i.e., on the side with the smaller clearance in the gear eccentricity direction of the gear pump 10. Under different speeds and loads, the gear eccentricity direction will vary, and the array of hydrostatic oil holes 1 covers the eccentricity direction of the gear pump 10 under various operating conditions, providing hydrostatic support for the gear shaft of the gear pump 10.

[0033] The hydrostatic oil hole 1 and the hydrostatic pipeline 2 together form a hydrostatic support. Under conditions such as low speed, heavy load, and load start-up of the gear pump 10, its gears will experience significant eccentricity. The bearing wall on the side with smaller clearance will be subjected to greater pressure, especially in the middle of the bearing height. At this time, after the high-pressure oil from the outlet passes through the flow channel, a pressure field is formed in the hydrostatic oil hole 1 and its surrounding area, generating a fluid reaction force to support the load and forming a liquid film of a certain thickness between the support surfaces, improving lubrication conditions, such as… Figure 6 As shown, a stable initial hydrostatic oil film can be established between the journal and the bushing 11, providing effective support force, preventing direct metal-to-metal contact, and reducing bearing wear.

[0034] like Figure 5 As shown, there are five rows of hydrostatic oil holes 1, connected to both ends of the horizontal hydrostatic pipes 2-3 in the hydrostatic pipeline 2. The inlet of the straight hydrostatic pipe 2-1 in the hydrostatic pipeline 2 is located in the middle, with no bends, resulting in minimal pressure loss. Therefore, the middle row of hydrostatic oil holes 1 provides the best support, corresponding to the area with the highest pressure concentration on the bearing. The remaining four rows of horizontal hydrostatic pipes 2-3 correspond to the E-type hydrostatic pipe bends 2-2. Due to the bends, these bends cause some oil pressure loss. This part of the pipeline acts as a damping orifice, causing the pressure inside the hydrostatic oil holes 1 to increase or decrease within a certain range with the load. When the load increases, the gap at the support surface decreases, and the hydraulic resistance increases, causing the pressure inside the hydrostatic oil holes 1 to increase, and the support force to increase accordingly, achieving a new balance between the load force and the support force. The same applies when the load decreases. Therefore, the hydrostatic oil holes 1 provide adaptive support.

[0035] The dynamic pressure oil groove 3 is located in the lubricating oil film area between the bushing 11 and the shaft of the gear pump, and is connected to the outlet of the gear pump 10 through the annular groove 6 and the drainage groove 7. Under normal operating conditions, due to the pressure imbalance within the gear pump 10, the gear shaft becomes eccentric, and the relative motion forms a converging wedge-shaped gap. The fluid in the dynamic pressure oil groove 3 is compressed in the wedge-shaped channel, generating additional dynamic lubrication pressure to enhance the oil film bearing capacity. Figure 6 As shown.

[0036] Through the above structural arrangement, the static pressure oil hole 1 and the dynamic pressure oil groove 3 work together to continuously provide stable oil film support during the transition from static to low speed of the gear pump 10, which significantly improves the operating reliability of the bearing under low speed and high load conditions, and effectively reduces starting wear, vibration and noise.

[0037] The bushing 11 features a two-body symmetrical design to facilitate the machining of complex flow channels and damping holes. For example... Figure 4 As shown, a sealing groove 9 is formed on the lower end face of the bushing 11, which is filled with a seal. After the gear pump 10 is assembled, the inner ring of the seal forms a low-pressure balance zone with the bushing 11 and the bushing end cover, while the outer ring forms a high-pressure balance zone with the bushing and the bushing end cover. When the gear pump 10 is running, the oil in the low-pressure oil chamber of the gear pump 10 flows into the low-pressure balance zone, while the oil in the high-pressure oil chamber flows into the high-pressure balance zone. Since the contact surface between the bushing 11 and the gear is at low pressure, the combined force formed by the two balance zones pushes the bushing towards the gear, which can effectively balance the axial force generated by the gear during the operation of the gear pump 10, reduce the axial leakage of the gear pump 10, alleviate the gear wear phenomenon, and improve the pump efficiency.

[0038] like Figure 7 As shown, the outer edge shape of the bushing 11 matches the inner wall of the shaft hole of the gear pump 10. When the gear pump 10 is in normal operation, the side of the bushing 11 fits tightly against the inner wall of the shaft hole, forming a closed pre-pressurized oil chamber between the gear and the pump body. This oil chamber allows the tooth tip clearance area near the outlet side to maintain a high pressure level close to the outlet cavity, effectively improving the sealing effect in this area. At the same time, the high-pressure area is extended to the low-pressure side through the high-pressure flow channel 5, further expanding the high-pressure coverage area and improving the sealing state between the tooth clearance volume and the pump casing, thereby significantly suppressing radial leakage and improving the volumetric efficiency and overall performance of the gear pump 10.

[0039] During operation, after the gear pump 10 starts, oil flows in from the inlet, quickly filling the pump body and continuously discharging from the outlet. Part of the oil near the outlet enters and fills the static pressure oil hole 1 through the static pressure pipe 2, while the other part enters the annular groove 6 along the guide groove 7, and then enters the dynamic pressure oil groove 3. Under conditions such as low speed, heavy load, or load-bearing start-up of the gear pump, the drive shaft 12 or driven shaft 13 may become eccentric within the bushing 11 (e.g., ...). Figure 6 As shown in the figure, the present invention introduces oil at the position between the bushing 11 and the driving shaft and the driven shaft, thereby avoiding direct contact between the shaft and the bushing, thus reducing friction and noise.

[0040] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bushing for reducing the minimum stable operating speed of a gear pump, characterized in that, The bushing (11) includes a driving wheel bushing (11-1), a driven wheel bushing (11-2), a hydrostatic support, and a hydrodynamic support; The driving wheel bushing (11-1) and the driven wheel bushing (11-2) are connected by a connecting body (11-3) and are symmetrically arranged about the connecting body (11-3); the hydrostatic support is installed inside the connecting body (11-3); the hydrostatic support includes a hydrostatic pipeline (2) and several hydrostatic oil holes (1); the hydrostatic oil holes (1) are connected to the hydrostatic pipeline (2); the hydrostatic pipeline (2) is located inside the connecting body (11-3), and the hydrostatic oil holes (1) are evenly distributed on the inner walls of the driving wheel bushing (11-1) and the driven wheel bushing (11-2); the inlet of the hydrostatic pipeline (2) is connected to the shaft hole (14) of the gear pump (10); The hydrodynamic support includes a plurality of hydrodynamic oil grooves (3); the hydrodynamic oil grooves (3) are located on the inner wall surfaces of the driving wheel bushing (11-1) and the driven wheel bushing (11-2), and each hydrodynamic oil groove (3) is arranged in parallel intervals with each other; The hydrostatic oil hole on the inner wall of the drive wheel bushing (11-1) is designated as the drive wheel hydrostatic oil hole (1-1), and the hydrostatic oil hole on the inner wall of the driven wheel bushing (11-2) is designated as the driven wheel hydrostatic oil hole (1-2). Both the drive wheel hydrostatic oil hole (1-1) and the driven wheel hydrostatic oil hole (1-2) are located on the side closer to the connecting body and are symmetrically arranged about the connecting body (11-3). The dynamic pressure oil groove (3) includes 3 to 5 driving wheel dynamic pressure oil grooves (3-1) and 3 to 5 driven wheel dynamic pressure oil grooves (3-2); adjacent driving wheel dynamic pressure oil grooves (3-1) are arranged at 90° intervals on the inner wall surface of the driving wheel bushing (11-1), and adjacent driven wheel dynamic pressure oil grooves (3-2) are arranged at 90° intervals on the inner wall surface of the driven wheel bushing (11-2); The drive wheel bushing (11-1) is fitted onto the drive shaft (12) of the gear pump (10), so that the inner wall of the drive wheel bushing (11-1) is indirectly in contact with the drive shaft (12) through the oil flowing through the drive wheel dynamic pressure oil groove (3-1) and the drive wheel static pressure oil hole (1-1); the driven wheel bushing (11-2) is fitted onto the driven shaft (13) of the gear pump (10), so that the inner wall of the driven wheel bushing is indirectly in contact with the driven shaft (13) through the oil flowing through the driven wheel dynamic pressure oil groove (3-2) and the driven wheel static pressure oil hole (1-2).

2. A bushing for reducing the minimum stable operating speed of a gear pump according to claim 1, characterized in that, The static pressure pipeline (2) includes a static pressure pipeline straight pipe (2-1), an E-type static pressure pipeline bend (2-2), and several rows of static pressure pipeline horizontal pipes (2-3) arranged parallel to each other vertically; the E-type static pressure pipeline bend (2-2) includes a main pipeline and several branch pipelines; one end of each branch pipeline is connected to the main pipeline, and each branch pipeline is arranged parallel to each other at intervals; The straight pipe (2-1) of the static pressure pipeline is connected to the main pipeline, and the end of each branch pipeline away from the main pipeline is connected to the middle of the horizontal pipe (2-3) of the static pressure pipeline; the two ends of the horizontal pipe (2-3) of the static pressure pipeline are respectively connected to the static pressure oil hole (1-1) of the driving wheel and the static pressure oil hole (1-2) of the driven wheel.

3. A bushing for reducing the minimum stable operating speed of a gear pump according to claim 1, characterized in that, The top end face of the connecting body (11-3) is provided with a first unloading groove (8). The top inner circumference end faces of the driving wheel bushing (11-1) and the driven wheel bushing (11-2) are both provided with annular grooves (6). The bottom of the annular groove (6) is connected to the top of the dynamic pressure oil tank (3). The annular groove (6) and the first unloading groove (8) are connected by a horizontal diversion groove (7). The diversion groove (7) is used to introduce the oil in the gear pump (10) into the annular groove (6) and the dynamic pressure oil tank (3).

4. A bushing for reducing the minimum stable operating speed of a gear pump according to claim 3, characterized in that, The top end face of the connector (11-3) is also provided with a second unloading groove (4) that is symmetrical to the first unloading groove (8).

5. A bushing for reducing the minimum stable operating speed of a gear pump according to claim 3 or 4, characterized in that, The bottom end face of the bushing (11) is provided with a sealing ring groove (9), and the sealing ring groove (9) is filled with a sealing element.

6. A bushing for reducing the minimum stable operating speed of a gear pump according to claim 5, characterized in that, Both the top outer circumferential end face edges of the driving wheel bushing (11-1) and the driven wheel bushing (11-2) are provided with flow grooves (5).

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