Throttling and pressure reducing structure for self-balancing multi-stage pump

Abstract

The utility model relates to the field of multi-stage pumps, in particular to a throttling pressure reduction structure for a self-balancing multi-stage pump, which comprises a first-stage water inlet section, a water outlet section and a second-stage water inlet section which are sequentially arranged along the length direction of a pump shaft, and a front throttling bush and a rear throttling bush are respectively fixed on the inner walls of the water outlet section and the second-stage water inlet section; a front throttling shaft sleeve and a rear throttling shaft sleeve corresponding to the front throttling bush and the rear throttling bush are fixed to the pump shaft respectively, outer spiral grooves with opposite spiral directions are formed in the outer wall of the front throttling shaft sleeve and the outer wall of the rear throttling shaft sleeve respectively, and the spiral direction of the outer spiral grooves of the front throttling shaft sleeve is the same as the rotating direction of the pump shaft. A plurality of groove parts are formed in the end faces of the sides, close to high-pressure fluid, of the front throttling bush and the rear throttling bush in the radial direction. According to the utility model, more effective throttling and pressure reducing effects can be achieved, and the sealing effect between pressure difference structures in the multistage pump is ensured.

Description

Technical Field

[0001] The present application relates to the field of multi-stage pumps, and in particular to a throttling and pressure reducing structure for a self-balancing multi-stage pump. Background Art

[0002] The self-balancing multi-stage pump adopts two sets of impellers with opposite directions symmetrically installed on the pump shaft inside the pump body. After the water is pressurized by the forward impeller group of the first-stage water inlet section, it is transported to the second-stage water inlet section through the connecting pipe from the first-stage outlet of the water outlet section, and then pressurized by the reverse impeller group in the second-stage water inlet section, and output from the second-stage outlet of the water outlet section. During the operation of the pump, due to the symmetrical layout of the forward and reverse impeller groups, the axial force on the pump shaft is self-balanced, and the residual axial force is borne by the angular bearing, so its reliability is effectively improved compared with the traditional multi-stage pump.

[0003] Since the suction port of the secondary water inlet section is in the high-pressure area after the primary pressurization, there is a pressure difference area between the secondary pressurization and the primary pressurization between the primary outlet and the secondary outlet of the water outlet section. As a mechanical structure that rotates at high speed, there must be a gap between the pump shaft and the housing of the above-mentioned components of the multi-stage pump. Under the action of the high pressure difference, the liquid will leak from the high-pressure area to the low-pressure area. The throttling and decompression structure commonly used is a combination of a throttling bushing and a throttling shaft sleeve. For example, CN208503028U discloses a well-sealed balanced multi-stage centrifugal pump, in which a front throttling bushing is fixed on the inner wall of the water outlet section, and a rear throttling bushing is provided on the inner wall of the rear water inlet section. A front throttling shaft sleeve and a rear throttling shaft sleeve are provided at corresponding positions of the pump shaft, and an annular groove is provided on the outer walls of the front throttling shaft sleeve and the rear throttling shaft sleeve, thereby extending the distance that the water in the high-pressure area flows through the gap between the throttling shaft sleeve and the throttling bushing to the low-pressure area, thereby reducing leakage. However, as the pump head increases, the throttling effect of this structure that simply increases the fluid flow distance will decrease, thereby affecting the efficiency of the multi-stage pump. Utility Model Content

[0004] In order to solve the above-mentioned deficiencies of the prior art, the present application provides a throttling and pressure reducing structure for a self-balancing multi-stage pump, which improves the sealing effect between the pressure difference structures in the multi-stage pump.

[0005] The technical solution of the utility model is: a throttling and decompression structure for a self-balancing multi-stage pump, comprising a primary water inlet section, a water outlet section and a secondary water inlet section which are sequentially arranged along the length direction of the pump shaft, a front throttling bushing and a rear throttling bushing are respectively fixed on the inner walls of the water outlet section and the secondary water inlet section, a front throttling sleeve and a rear throttling sleeve corresponding to the front throttling bushing and the rear throttling bushing are respectively fixed on the pump shaft, outer spiral grooves which are arranged in opposite spiral directions are respectively opened on the outer walls of the front throttling sleeve and the rear throttling sleeve, and the spiral direction of the outer spiral groove of the front throttling sleeve is the same as the rotation direction of the pump shaft, and a plurality of grooves are radially opened on the end surfaces of the front throttling sleeve and the rear throttling sleeve on one side close to the high-pressure fluid. The structural arrangement of the positive outer spiral groove on the front throttle sleeve and the reverse outer spiral groove on the rear throttle sleeve generates a spiral lift force in the opposite direction of the fluid flow direction for the fluid flowing through the gap between the throttle sleeve and the throttle bushing, thereby suppressing fluid leakage. The groove portions arranged at the end faces of the front throttle bushing and the rear throttle bushing radially cut the high-pressure fluid located on the outside of the bushing, increasing the friction with the fluid, thereby reducing the rotational force when the high-pressure fluid enters the gap, weakening the energy of the fluid, and further suppressing fluid leakage.

[0006] The two ends of the groove portion extend radially and are respectively connected to the inner and outer sides of the front throttle bushing / rear throttle bushing. The groove portion is designed as a through groove to maximize the cutting area of ​​the groove portion and the high-pressure fluid.

[0007] An annular boss is formed on the fixing position between the front throttling bushing and the water outlet section, and on the fixing position between the rear throttling bushing and the secondary water inlet section. The annular boss is fixedly connected to the inner wall of the water outlet section / secondary water inlet section via bolts, and the groove portion is respectively arranged on the annular boss of the front throttling bushing and on the end face of the rear throttling bushing away from the annular boss.

[0008] The inner side of the secondary water inlet section is divided into a high-pressure water inlet chamber and a balance chamber through a partition in a direction away from the water outlet section. The rear throttling bushing is fixed on the inner wall of the partition, and the balance chamber is connected to the water inlet chamber of the primary water inlet section through a balance pipe. The balance pipe balances the high-pressure fluid seeping from the suction port of the secondary water inlet section, thereby relieving a part of the axial residual stress, avoiding the high-pressure fluid from squeezing the mechanical seal at the connection between the secondary water inlet section and the pump shaft, and ensuring the effect and service life of the mechanical seal.

[0009] Inner spiral grooves are provided on the inner walls of the front throttle bushing and the rear throttle bushing, and the spiral direction of the inner spiral groove is opposite to the spiral direction of the corresponding outer spiral groove.

[0010] The tooth bottom of the inner spiral groove is arranged correspondingly to the tooth top of the outer spiral groove, and a labyrinth-shaped flow channel gap is formed between the inner spiral groove and the outer spiral groove. Due to the existence of the labyrinth-shaped flow channel gap, the turning points of the water flow increase after entering the gap, the contact area between the water flow and the bushing and the shaft sleeve increases, and its own kinetic energy is further lost, and the pressure is also reduced, thereby suppressing the leakage of the fluid.

[0011] The length of the front throttle bushing is greater than the length of the rear throttle sleeve.

[0012] The beneficial effects of the utility model are as follows: by respectively arranging a positive external spiral groove and a reverse external spiral groove on the front throttle sleeve and the rear throttle sleeve, a spiral lift opposite to the flow direction of the fluid is generated for the fluid flowing through the gap between the throttle sleeve and the throttle bushing, thereby offsetting the kinetic energy of the fluid; at the same time, groove portions are arranged at the end faces of the front throttle bushing and the rear throttle bushing, thereby radially cutting the high-pressure fluid located on the outside of the bushing, increasing the friction with the fluid, reducing the rotational force when the high-pressure fluid enters the gap, weakening the energy of the fluid, thereby inhibiting fluid leakage, and ensuring the sealing effect between the pressure difference structures in the multi-stage pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional schematic diagram of the utility model applied to a multi-stage pump;

[0014] Figure 2 It is a side view of the utility model applied to a multi-stage pump;

[0015] Figure 3 yes Figure 1 A partial enlarged view of middle A;

[0016] Figure 4 yes Figure 1 A partial enlarged view of B in the middle;

[0017] Figure 5 It is a structural schematic diagram of the front throttle bushing in the utility model;

[0018] Figure 6 It is a structural schematic diagram of the middle and rear throttling bushing of the utility model.

[0019] Reference numerals:

[0020] 1. First-stage water inlet section; 2. Water outlet section; 201. Last-stage counter-impeller chamber; 202. Last-stage impeller chamber; 3. Second-stage water inlet section; 301. Partition; 302. Balance chamber; 303. High-pressure water inlet chamber; 4. Pump shaft; 5. Mechanical seal; 6. Front throttle bushing; 7. Front throttle sleeve; 8. Rear throttle bushing; 9. Rear throttle sleeve; 10. Balance pipe; 11. Connecting pipe; 12. External spiral groove; 13. Internal spiral groove; 14. Groove portion; 15. Annular boss. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0023] In the present application, the self-balancing multi-stage pump is composed of a primary water inlet section 1, a water outlet section 2 and a secondary water inlet section 3 to form a pump body structure. The installation method of the impeller group, mechanical seal 5, angular bearing and other structures in the pump body is the same as the prior art and will not be repeated here.

[0024] refer to Figure 1-Figure 3 The present application provides a throttling and decompression structure for a self-balancing multi-stage pump, wherein a front throttling bushing 6 and a rear throttling bushing 8 are respectively fixed on the inner walls of a water outlet section 2 and a secondary water inlet section 3, and a front throttling sleeve 7 and a rear throttling sleeve 9 corresponding to the front throttling sleeve 6 and the rear throttling sleeve 8 are respectively fixed on a pump shaft 4, and outer walls of the front throttling sleeve 7 and the rear throttling sleeve 9 are respectively provided with outer spiral grooves 12 arranged in opposite spiral directions, and the spiral direction of the outer spiral groove 12 of the front throttling sleeve 7 is the same as the rotation direction of the pump shaft 4, and the structural arrangement of the positive outer spiral groove 12 on the front throttling sleeve 7 and the reverse outer spiral groove 12 on the rear throttling sleeve 9 generates a spiral lift force opposite to the flow direction of the fluid flowing through the gap between the throttling sleeve and the throttling sleeve, that is, Figure 3 As shown, the fluid pressure of the secondary pressurization in the last-stage reverse impeller chamber 201 on the right side of the water outlet section 2 is higher than the fluid pressure of the primary pressurization in the last-stage impeller chamber 202 on the left side of the water outlet section 2. At this time, the leakage direction of the fluid is from right to left. Since the spiral direction of the outer spiral groove 12 on the front throttling sleeve 7 is the same as the direction of the pump shaft 4, the spiral lift generated by it is consistent with the water flow direction formed by the positive impeller group, that is, from left to right, thereby suppressing the fluid leakage between the water outlet section 2 and the pump shaft 4; similarly, Figure 4 As shown, the fluid leakage direction at the suction port of the secondary water inlet section 3 is from left to right, and the spiral direction of the outer spiral groove 12 on the rear throttling sleeve 9 is opposite to the direction of the pump shaft 4. The spiral lift generated is consistent with the water flow direction formed by the counter-impeller group, that is, from right to left, thereby suppressing the fluid leakage between the secondary water inlet section 3 and the pump shaft 4.

[0025] Further, such as Figure 5 and Figure 6As shown, a plurality of grooves 14 are radially provided on the end faces of the front throttling bushing 6 and the rear throttling bushing 8 on one side close to the high-pressure fluid. In this embodiment, an annular boss 15 is formed on the fixed position of the front throttling bushing 6 and the water outlet section 2, and the fixed position of the rear throttling bushing 8 and the secondary water inlet section 3. The annular boss 15 is fixedly connected to the inner wall of the water outlet section 2 / secondary water inlet section 3 by bolts. The grooves 14 are respectively provided on the annular boss 15 of the front throttling bushing 6 and the end face of the rear throttling bushing 8 away from the annular boss 15. By providing the grooves 14 on the end faces of the front throttling bushing 6 and the rear throttling bushing 8, the high-pressure fluid located outside the bushing is radially cut, the friction area and friction force with the fluid are increased, thereby reducing the rotational force when the high-pressure fluid enters the gap, weakening the energy of the fluid, and further inhibiting fluid leakage.

[0026] In order to maximize the cutting area between the groove 14 and the high-pressure fluid, the two ends of the groove 14 extend radially and are respectively connected to the inner and outer sides of the front throttle bushing 6 / rear throttle bushing 8. At this time, since the area of ​​the groove 14 of the front throttle sleeve 7 is significantly larger than the area of ​​the groove 14 of the rear throttle sleeve 9, the throttling and decompression effect of the higher pressure at the water outlet section 2 can be met without changing other structures of the existing throttle sleeve. Further preferably, the length of the front throttle bushing 6 is greater than the length of the rear throttle sleeve 9.

[0027] like Figure 1 and Figure 2 As shown, the inner side of the secondary water inlet section 3 is divided into a high-pressure water inlet chamber 303 and a balance chamber 302 through a partition 301 along a direction away from the water outlet section 2. The rear throttling bushing 8 is fixed on the inner wall of the partition 301. The balance chamber 302 is connected with the water inlet chamber of the primary water inlet section 1 through a balance pipe 10. The high-pressure water inlet chamber 303 is connected with the last-stage impeller chamber 202 on the left side of the water outlet section 2 through a connecting pipe 11. By setting the balance pipe 10, the high-pressure fluid seeping out from the suction port of the secondary water inlet section 3 can be balanced, thereby relieving a part of the axial residual stress, avoiding the high-pressure fluid from squeezing the mechanical seal 5 at the connection between the secondary water inlet section 3 and the pump shaft 4, and ensuring the effect and service life of the mechanical seal 5.

[0028] like Figure 3 and Figure 4As shown, inner spiral grooves 13 are provided on the inner walls of the front throttling bushing 6 and the rear throttling bushing 8, and the spiral direction of the inner spiral groove 13 is opposite to the spiral direction of the corresponding outer spiral groove 12. Specifically, the tooth bottom of the inner spiral groove 13 is corresponding to the tooth top of the outer spiral groove 12, and a labyrinth-like flow channel gap is formed between the inner spiral groove 13 and the outer spiral groove 12. In order to avoid interference between the throttling bushing and the throttling sleeve during installation, a gap height of 10-15 threads is provided between the tooth top of the inner spiral groove 13 and the tooth top of the outer spiral groove 12. Due to the existence of the labyrinth-like chute gap, the number of inflection points increases after the water flow enters the gap, and at the same time, the infiltrated fluid is converged, the contact area between the water flow and the bushing and the sleeve increases, and its own kinetic energy is further lost, and the pressure is also reduced, thereby further suppressing the leakage of the fluid.

[0029] The throttling and decompression structure of the present application is installed between the outlet section 2 and the secondary water inlet section of the self-balancing multi-stage pump and the pump shaft 4. Through the combined effect of the spiral lift of the outer spiral groove 12, the radial resistance of the groove portion 14 and the beam force of the labyrinth flow channel gap, it plays a more effective throttling and decompression role compared to the single structure in the prior art, ensures the sealing effect between the pressure difference structures in the multi-stage pump, and thus can be better applied in high-lift multi-stage pumps.

[0030] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A throttling and decompression structure for a self-balancing multi-stage pump, comprising a primary water inlet section, a water outlet section and a secondary water inlet section sequentially arranged along the length direction of the pump shaft, a front throttling bushing and a rear throttling bushing are respectively fixed on the inner walls of the water outlet section and the secondary water inlet section, and a front throttling sleeve and a rear throttling sleeve corresponding to the front throttling sleeve and the rear throttling sleeve are respectively fixed on the pump shaft, characterized in that: The outer walls of the front throttle sleeve and the rear throttle sleeve are respectively provided with external spiral grooves arranged in opposite spiral directions, and the spiral direction of the external spiral groove of the front throttle sleeve is the same as the rotation direction of the pump shaft. The front throttle sleeve and the rear throttle sleeve are radially provided with a plurality of grooves on the end surfaces on one side close to the high-pressure fluid.

2. The throttling and decompression structure for a self-balancing multi-stage pump according to claim 1, characterized in that: The two ends of the groove portion extend radially and are respectively connected to the inner and outer sides of the front throttle bushing / the rear throttle bushing.

3. The throttling and decompression structure for a self-balancing multi-stage pump according to claim 2, characterized in that: An annular boss is formed on the fixing position between the front throttling bushing and the water outlet section, and on the fixing position between the rear throttling bushing and the secondary water inlet section. The annular boss is fixedly connected to the inner wall of the water outlet section / secondary water inlet section via bolts, and the groove portion is respectively arranged on the annular boss of the front throttling bushing and on the end face of the rear throttling bushing away from the annular boss.

4. The throttling and decompression structure for a self-balancing multi-stage pump according to any one of claims 1 to 3, characterized in that: The inner side of the secondary water inlet section is divided into a high-pressure water inlet chamber and a balance chamber through a partition along a direction away from the water outlet section. The rear throttling bushing is fixed on the inner wall of the partition. The balance chamber is connected with the water inlet chamber of the primary water inlet section through a balance pipe.

5. The throttling and decompression structure for a self-balancing multi-stage pump according to any one of claims 1 to 3, characterized in that: Inner spiral grooves are provided on the inner walls of the front throttle bushing and the rear throttle bushing, and the spiral direction of the inner spiral groove is opposite to the spiral direction of the corresponding outer spiral groove.

6. The throttling and decompression structure for a self-balancing multi-stage pump according to claim 5, characterized in that: The tooth bottom of the inner spiral groove and the tooth top of the outer spiral groove are arranged correspondingly, and a labyrinth-shaped flow channel gap is formed between the inner spiral groove and the outer spiral groove.

7. The throttling and decompression structure for a self-balancing multi-stage pump according to any one of claims 1 to 3, characterized in that: The length of the front throttle bushing is greater than the length of the rear throttle sleeve.

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