Background
The centrifugal pump is a general hydraulic machine with a wide application range, and is widely applied to water supply and drainage, agricultural engineering, industrial engineering, aerospace and navigation engineering, energy engineering, vehicle engineering and the like.
With the rapid development of modern science and technology, the application range of the pump is rapidly expanded, and the performance requirements of modern engineering technology on the pump are higher and higher. According to the 2007 report of international academic conference of fluid machinery and engineering: the electricity consumption of various pumps in China accounts for 20% of the total electricity consumption of the whole country every year, and the oil consumption accounts for about 50% of the total oil consumption of the whole country. The technical level of the centrifugal pump in China at present has no gap from the comprehensive technical level in comparison with the technology of a centrifugal pump at abroad through decades of development.
The sealing failure of the shaft sealing device in the operation of domestic and domestic centrifugal water pumps is the main reason influencing the safe and economic operation of the water pumps, the maintenance cost of the centrifugal pumps is 70 percent for processing the sealing failure, the sealing performance of the shaft sealing device of the water pumps is an important index for evaluating the quality of the pumps, the mechanical efficiency and the volumetric efficiency of the water pumps are directly influenced, and the leakage generated by the sealing gaps between the pump shaft and the pump shell at the suction side and the discharge side is the root cause of the accident. The common shaft seal modes of the centrifugal pump comprise a packing seal and a mechanical seal, and the mechanical seal has poor adaptability to media, higher cost and maintenance cost and less use. Most commonly, the packing seal is used, and referring to fig. 1, in the conventional multistage centrifugal pump 100 using the packing seal, the suction section 110 and the left packing gland 120 cooperate to form a space for accommodating the packing 130, the packing box body 150 and the right packing gland 160 are disposed at the end of the water outlet section 140, and the packing box body 150 and the right packing gland 160 cooperate to form a space for accommodating the packing 130, so as to realize the seal of the multistage centrifugal pump. Due to the defects of the packing seal and the problem of poor adaptability to the water pump, the failure rate is high in use, and the safe and economic operation of the water pump is finally directly influenced.
The packing seal causes the following technical problems due to continuous friction: the method comprises the following steps of 1, affecting the efficiency of a water pump, wherein the roughness is increased along with the abrasion of a shaft sleeve of a first pump and a second pump of the water pump, the mechanical efficiency of the water pump is reduced along with the increase of the friction force, the mechanical efficiency of a new pump is affected by a packing seal at the initial stage by 2%, and the abrasion of the shaft sleeve reaches more than 5% in the later stage (introduced in the text of 'good and poor packing seal of a centrifugal pump', the packing seal needs 10% -15% of shaft power to overcome the friction force between the shaft sleeve and the packing to achieve sealing). The friction heating often causes the accidents of filler smoking, which causes potential safety hazards to the underground coal mine and chemical field. 2. Because the filler and the shaft sleeve rub to form a gap, the compensation of the filler is poor, the leakage is increased, the vacuum degree of a water suction port of the water pump is reduced, the light water pump generates cavitation erosion, an impeller and a guide wing of the water pump are quickly damaged, and the heavy water pump does not feed water, a rotor and a pump shell rub together in a dry way, so that the locking accident of a water pump shaft occurs; 3. in the remote automatic control of the water pump, the clearance between the filler and the pump shaft sleeve caused by abrasion in the previous operation cannot be automatically eliminated, the vacuumizing remote control of the water pump in the pump shell cannot be realized before the next operation, and the water pump cannot be started. If the underground main drainage pump of the coal mine cannot realize the remote starting of the ground dispatching room of the water pump due to the reason; 4. the maintenance cost is big, often changes the filler, the axle sleeve.
Disclosure of Invention
In view of the above, it is desirable to provide a centrifugal water pump with reduced seal friction.
The utility model provides a centrifugal water pump, including bearing frame, impeller, the pump shaft, pump case and pressure seal assembly, the bearing frame bears the pump shaft, the impeller is installed on the pump shaft, the pump shaft is worn out from the both ends of pump case, the impeller is located the pump case, the pressure seal assembly cover is established on the pump shaft and pressure seal assembly and pump shaft can relative rotation, the pump shaft with the pressure seal assembly corresponding on the surface be provided with the wearing layer, pressure seal assembly takes place deformation according to the effect state of external pressure medium, pressure seal assembly utilizes the deformation of self and pump shaft, the dynamic seal of centrifugal water pump is accomplished in the pump case cooperation, dynamic seal indicates: before the centrifugal water pump is started, the deformation part of the pressure sealing assembly deforms under the pressure applying state of an external pressure medium, so that the deformation part of the pressure sealing assembly is in contact with the pump shaft to realize sealing; after the centrifugal water pump is started and the pressure state of an external pressure medium is cancelled, the deformation of the deformation part of the pressure sealing assembly is recovered to remove the pressure contact sealing with the pump shaft, and the deformation part is made of the same material as the wear-resistant layer to reduce the friction force between the deformation part and the wear-resistant layer.
In the centrifugal water pump, the pressure sealing component is sleeved on the pump shaft and can relatively rotate with the pump shaft, the surface of the pump shaft corresponding to the pressure sealing component is provided with a wear-resistant layer, the pressure sealing component deforms according to the action state of an external pressure medium, the pressure sealing component is matched with the pump shell by utilizing the deformation of the pressure sealing component to complete the dynamic sealing of the centrifugal water pump, before the centrifugal water pump is started, the deformation part of the pressure sealing component deforms under the pressure applying state of the external pressure medium, so that the deformation part of the pressure sealing component is in contact with the pump shaft to realize the sealing, after the centrifugal water pump is started and the pressure applying state of the external pressure medium is cancelled, the deformation of the deformation part of the pressure sealing component is recovered to remove the pressure contact sealing with the pump shaft, and the deformation part is the same as the wear-resistant layer in material, so that the duration time of contact friction can be reduced, ensuring the continuous and reliable operation of the centrifugal water pump.
Drawings
Fig. 1 is a schematic structural view of a conventional centrifugal water pump.
Fig. 2 is a schematic structural view of a centrifugal water pump according to a preferred embodiment of the present application.
FIG. 3 is a schematic view of the pressure seal assembly and pump shaft of FIG. 2.
In the figure: the multistage centrifugal pump comprises a multistage centrifugal pump 100, a suction section 110, a left packing gland 120, a sealing packing 130, a water outlet section 140, a packing box body 150, a right packing gland 160, a middle section 170, a centrifugal water pump 10, a balance chamber 11, a pressure medium conveying pipe 12, an evacuation pipe 13, a bearing seat 20, an impeller 30, a pump shaft 40, a wear layer 41, a pump shell 50, a communication pipe 51, a suction section 52, a water suction side pressure water inlet chamber 522, a middle section 53, a water outlet section 54, a packing box body 55, a water discharge side pressure water inlet chamber 551, a pressure sealing assembly 60, an annular deformation member 61, an annular accommodating space 62, a base 63, a first shaft sleeve 631, a second shaft sleeve 632, a gland 64, a spacer ring 65, an oil filling nozzle 66, a balance water pipe 70, a one-way valve 71, a sealing control device 80, a control unit 81, a vacuum pump 82, a pressure water pipeline 83 and a controlled electric valve 84.
Detailed Description
Referring to fig. 2 and 3, the centrifugal water pump 10 includes a bearing seat 20, an impeller 30, a pump shaft 40, a pump housing 50 and a pressure seal assembly 60, the bearing seat 20 bears the pump shaft 40, the impeller 30 is mounted on the pump shaft 40, the pump shaft 40 penetrates through two ends of the pump housing 50, the impeller 30 is located in the pump housing 50, the pressure seal assembly 60 is sleeved on the pump shaft 40, the pressure seal assembly 60 and the pump shaft 40 can rotate relatively, the pressure seal assembly 60 deforms according to an action state of an external pressure medium, the pressure seal assembly 60 cooperates with the pump shaft 40 and the pump housing 50 by using its own deformation to complete dynamic sealing of the centrifugal water pump, and the dynamic sealing refers to: before the centrifugal water pump 10 is started, the deformation part of the pressure sealing assembly 60 deforms under the pressure applying state of an external pressure medium, so that the deformation part of the pressure sealing assembly 60 is in pressure contact with the pump shaft 40 to realize sealing; after the centrifugal water pump is started and the pressure state of the external pressure medium is removed, the deformation of the deformed part of the pressure seal assembly 60 is recovered to release the pressure contact seal with the pump shaft 40. The pressure medium may be a flowing substance, such as water, gas.
Further, the pressure seal assembly 60 is provided with an annular deformation member 61 and an annular accommodating space 62 which is used for receiving an external pressure medium and is matched with the annular deformation member, the annular deformation member 61 is the deformation part, the diameter of the annular deformation member 61 is smaller than that of the annular deformation member accommodating space 62, the annular deformation member 61 is fixed in the annular accommodating space 62, and the outer edge of the annular deformation member 61 is not in contact with the side wall of the surrounding annular accommodating space 62 to form a gap for the external pressure medium to enter; the annular deformation piece 61 fixed in the annular accommodating space 62 is sleeved on the pump shaft 40, a gap b is formed between the annular deformation piece 61 and the pump shaft 40, the value range of the gap b is larger than 0 and smaller than 0.05mm, and the annular deformation piece 61 deforms towards the axis of the pump shaft 40 under the action of an external pressure medium and contacts with the surface of the pump shaft 40, so that the centrifugal water pump 10 is sealed. The pressure seal assembly 60 comprises an annular deformation part 61, a base 63 and a gland 64, wherein the annular deformation part 61 is sleeved on the pump shaft, the base 63 comprises a first shaft sleeve 631 and a second shaft sleeve 632, a first end of the first shaft sleeve 631 is fixedly connected with a first section of the second shaft sleeve 632, the inner diameter of the first shaft sleeve 631 is matched with the outer diameter of the pump shaft 40, the inner diameter of the first shaft sleeve 631 is smaller than the inner diameter of the second shaft sleeve 632, the diameter of the annular deformation part 61 is smaller than the inner diameter of the second shaft sleeve 632 and larger than the outer diameter of the pump shaft 40, a second end of the second shaft sleeve 632 is relatively fixed with the gland 64, a space formed among the second shaft sleeve 632, the gland 64 and the pump shaft 40 is an annular accommodating space 62, the gland 64 and the first shaft sleeve 631 tightly press and fix the annular deformation part 61 located in the annular accommodating space 64, and an annular gap between the second shaft sleeve 632 and the annular deformation part 61 is used for an external pressure medium to enter; the second end of the first sleeve 631 is fixedly coupled to the pump housing 50. The pressing of the annular deforming member 61 by the gland 64 can adjust a natural gap (working gap b) between the annular deforming member 61 and the pump shaft 40.
In this embodiment, the pressure seal assembly 60 includes two annular deformation members 61 and further includes a spacer ring 65, the two annular deformation members 61 and the spacer ring 65 are disposed in the annular receiving space 62, and the spacer ring 65 is located between the two annular deformation members 61. The annular deformation part 61 is a sealing ring with polyurethane components, and the cross section of the annular deformation part 61 is large in outside and small in inside, so that the large-area part is utilized to bear the pressure of an external pressure medium, and the deformation accuracy and effectiveness of the annular deformation part are further improved. The gland 64 is bored with an oil filler hole, and an oil filler nozzle 66 is installed in the oil filler hole.
Further, the surface of the pump shaft 40 is provided with the wear-resistant layer 41 with polyurethane components, and as the wear-resistant layer 41 and the annular deformation part 61 are made of the same material, the resistance of the wear-resistant layer 41 and the annular deformation part 61 during relative movement can be reduced, and the friction is reduced. An annular groove is formed in the position, corresponding to the second shaft sleeve 632, of the pump shaft 40, the wear-resistant layer 41 is arranged in the annular groove, and the thickness of the wear-resistant layer 41 is matched with the depth of the annular groove.
In this embodiment, the centrifugal water pump 10 includes two pressure sealing assemblies 60, and the two pressure sealing assemblies 60 are sleeved on two ends of the pump shaft 40 and are correspondingly and fixedly connected to two ends of the housing 50. The pump case 50 has a communication pipe 51, and the communication pipe 51 is used for sending the received pressure water with the pressure P in the balance chamber 11 of the centrifugal water pump 10 to the matching gap b between the first shaft sleeve 631 on the water suction side and the pump shaft 402The pressure water of pressure P in the balance chamber 11 enters the fitting gap b between the first sleeve 631 and the pump shaft 40 on the drain side1To effect sealing and increase air leakage resistance.
Further, the pump shell 50 includes a communicating pipe 51, a suction section 52, a middle section 53, a water outlet section 54, and a packing box body 55, the suction section 52, the middle section 53, the water outlet section 54, and the packing box body 55 are sequentially connected, one of the pressure sealing assemblies 60 is connected with the packing box body 521 of the suction section 52 in a matching manner, and forms a suction side pressure water inlet chamber 522; another pressure seal assembly 60 is fitted into the stuffing box 55 attached to the outlet section 54 and forms a discharge side pressure water inlet chamber 551; a first end of the connection pipe 51 is connected to the water suction side pressure water inlet chamber 522, a second end of the connection pipe 51 is connected to the water discharge side pressure water inlet chamber 551, and water in the equilibrium chamber 11 of the centrifugal water pump 10 passes through a fitting gap b between the corresponding box and the pump shaft1The pressure water enters the chamber 551 at the water discharge side, then flows into the pressure water entering chamber 522 at the water suction side through the connection pipe 51, and then passes through the fitting gap b between the corresponding box body and the pump shaft2Enters the water suction port of the water pump so as to realize sealing and increase air leakage resistance.
The principle of the solution of the present application is further explained below, based on the leakage q = pi dh of the concentric annular gap3Δ p/12 μ L, the amount of leakage is proportional to the pressure difference Δ p across the gap. Therefore, the structure can be utilized to achieve the purpose of reducing the pressure difference, and the specific principle is as follows: after the water pump is operated, the pressure water in the balance chamber is pressure P which is greater than the pressure P of the water suction port of the water pump3The water in the balance chamber passes through the gap b1A drain side pressure water inlet chamber 551, a communication pipe 51 leading to a suction side pressure water inlet chamber 522 and then passing through a gap b2Enters the water suction port of the water pump, and the pressure of pressure water entering the water suction side pressure water chamber 522 is P2Since the suction-side pressure water inlet chamber 522 and the discharge-side pressure water inlet chamber 551 communicate with each other through the communication pipe 51, P is a value excluding the piping resistance1≈P2Due to increased pressure of P, P1 、P2Following the increase of height P0 - P1 、P0 - P2Decrease in pressure difference of P0The air leakage of the water pump through the sealing ring is reduced during the operation of the water pump for the atmospheric pressure of the installation place of the water pump, thereby achieving the purposes of reducing the air leakage of the water pump shaft and the pump shellThe problem of sealing. Further, a check valve 71 is provided in the balance water pipe 70 of the centrifugal water pump 10 to increase the pressure of the pressurized water in the balance chamber 11 by the check valve 71.
Two states of operation of the pressure seal assembly 60: the first state is before the water pump starts, vacuum water injection in the pump casing for annular deformation piece 61 and pump shaft 40 are gapless state when pressurized contact, and the second state is when water pump starts after the normal operating, annular deformation piece 61 and pump shaft 40 resume gapped state when the deformation is resumeed to the non-pressure. Before the water pump is ready to be started, the pressure water remote control electric valve in the sealing control device is opened, and the pressure water simultaneously supplies water to the vacuum pump and the pressure sealing assembly 60 in the sealing control device. The vacuum jet pump discharges air in the pump case 40, pressure water is injected into an annular gap H cavity between the second shaft sleeve 632 and the annular deformation parts 61 through the communicating pipe 51, the two groups of annular deformation parts 61 are pressed towards the axis of the water pump by the outer ring in the pressing direction, the annular deformation parts 61 are special-shaped sealing rings, the annular deformation parts 61 deform to change the original state without gap with the natural pressure of the pump shaft (the natural pressure without gap corresponds to '0.00 mm < gap b < 0.05 mm') into a state with pressure formed along the circumferential surface of the lip of the sealing ring towards the shaft to achieve the sealing effect, the inside of the pump case is isolated from the outside and forms 'vacuum' under the action of the vacuum jet pump, water enters the pump case along the water suction pipe under the external atmospheric pressure, the pump case is filled with water, and the vacuum valve is closed at the moment to create conditions for starting the water pump. At the moment, the water pump is started, the pump shaft 40 and the annular deformation piece 61 are started in a compressed gapless state, after the water pump is started, the vacuum jet pump pressure water switch is controlled to be powered off and water is stopped after short time delay, no pressure water exists in the cavity H, the annular deformation piece 61 restores the original state and is in a natural gapless state in contact with the pump shaft 40, and the water pump enters a normal operation state.
Further, the centrifugal water pump 10 further includes a pressure medium conveying pipe 12, the pressure medium conveying pipe 12 has two output pipe heads and one input pipe head, the two output pipe heads are correspondingly connected with the two second shaft sleeves 632 and respectively communicated with the annular gaps between the corresponding second shaft sleeves 632 and the annular deformation member 61; the inlet nipple of the pressure medium supply line 12 serves for receiving pressure medium.
Further, the centrifugal water pump 10 further includes a sealing control device 80, the sealing control device 80 is connected to the pressure medium conveying pipe 12 and the vacuum pumping pipe 13 of the centrifugal water pump 10, and the sealing control device 80 is configured to convey a pressure medium to the pressure medium conveying pipe 12, so that the annular deformation member 61 of the pressure seal assembly 60 deforms under a pressure state of the pressure medium, and the annular deformation member 61 contacts with the pump shaft 40 to realize sealing; the sealing control device 80 is also used for discharging air in the pump shell 50 by using the vacuumizing pipe 13 to form negative pressure in the pump shell 50, so that water enters the pump shell 50 along the suction pipe under the pressure of external atmospheric pressure; the sealing control device 80 is further configured to stop the pressure medium delivery and the vacuum pumping after a predetermined period of time after detecting the centrifugal water pump 10 is started.
Further, the sealing control device 80 includes a control unit 81, a vacuum jet pump 82, a pressure water pipe 83, and a controlled electric valve 84 disposed between the pressure water pipe 83 and the vacuum jet pump 82, and the pressure medium delivery pipe 12, the control unit 81 is electrically connected to the controlled electric valve 84 and the vacuum jet pump 82, the control unit 81 controls the vacuum jet pump 82 and the controlled electric valve 84 to operate according to the operation state of the centrifugal water pump 10, the vacuum jet pump 82 is connected to the vacuum pipe 13 of the centrifugal water pump 10 through a pipe to realize the vacuum pumping of the pump casing, and the pressure water pipe 83 delivers the pressure medium to the pressure medium delivery pipe 12 to realize the deformation sealing of the annular deformation member 61.
In the centrifugal water pump 10, the pressure sealing assembly 60 is sleeved on the pump shaft, the pressure sealing assembly 60 and the pump shaft 40 can rotate relatively, the pressure sealing assembly 60 deforms according to the action state of an external pressure medium, the pressure sealing assembly 60 completes dynamic sealing of the centrifugal water pump by utilizing the deformation of the pressure sealing assembly 60 and the pump shell in a matching way, before the centrifugal water pump 10 is started, the deformation part of the pressure sealing assembly 60 deforms under the pressure state of the external pressure medium, so that the deformation part of the pressure sealing assembly is in pressure contact with the pump shaft 40 to realize sealing, after the centrifugal water pump 10 is started and the pressure state of the external pressure medium is cancelled, the deformation of the deformation part of the pressure sealing component 60 is recovered, the pressure contact sealing with the pump shaft 40 is released, therefore, the duration of the contact friction can be reduced, and the continuous and reliable operation of the centrifugal water pump 10 is ensured.