Centrifugal compressor and mechanical refrigeration system

Abstract

The utility model discloses a centrifugal compressor which comprises a power component, a transmission shaft and a centrifugal impeller, the transmission shaft penetrates through the power component so that the power component can provide rotating power, and the centrifugal impeller is installed at the first end of the transmission shaft. The second end of the transmission shaft is inserted into the negative pressure cavity so that the end face of the transmission shaft can be in a negative pressure state, and the transmission shaft is further provided with a first thrust structure used for preventing the transmission shaft from going deep into the negative pressure cavity. According to the centrifugal compressor, the negative pressure cavity and the first thrust structure are matched with each other, so that the stability of the axial position can be well maintained, and axial movement is avoided. Meanwhile, due to negative pressure adsorption, the larger the axial tension is, the larger the corresponding negative pressure is, and compared with a thrust structure, the limiting effect is better. In conclusion, the centrifugal compressor can effectively solve the problem that an existing transmission shaft is poor in axial limiting effect. The utility model further discloses a mechanical refrigerating system comprising the centrifugal compressor.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioning, and more specifically, to a centrifugal compressor and also to a mechanical refrigeration system comprising the centrifugal compressor. Background Art

[0002] Existing air-suspended static pressure centrifugal compressors often generate axial unbalanced force due to the difference in impeller size and matching clearance. If the axial unbalance is not resolved, it will soon cause wear toward one side and damage the compressor. At present, the axial balancing force of its rotating shaft is usually provided by the external air supply pressure to the thrust plate connected to the rotating shaft through the bearing. When the thrust plate points axially to the motor side, the gap between the bearing and the thrust plate on the motor side is reduced, the pressure is increased, and a reverse thrust is provided, and vice versa. The disadvantage of this method is that no matter whether the thrust plate is sandwiched between the bearing or the bearing is sandwiched between the thrust plate, both positive and negative thrusts need to be provided, which causes air supply loss.

[0003] In the process of realizing the present utility model, the inventor discovered that there are at least the following problems in the prior art: How to effectively solve the problem of poor axial limiting effect of the current transmission shaft is an urgent problem that technicians in this field need to solve. Utility Model Content

[0004] In view of this, an object of the present invention is to provide a centrifugal compressor, which can effectively solve the problem of poor axial limiting effect of the current transmission shaft. A second object of the present invention is to provide a mechanical refrigeration system including the above-mentioned centrifugal compressor.

[0005] In order to achieve the above first purpose, the utility model provides the following technical solutions:

[0006] A centrifugal compressor comprises a power component, a transmission shaft and a centrifugal impeller, wherein the transmission shaft passes through the power component so as to be provided with rotational power by the power component, the centrifugal impeller is installed on the first end of the transmission shaft, the second end of the transmission shaft is inserted into a negative pressure cavity so that the end face of the transmission shaft can be in a negative pressure state, and the transmission shaft is also provided with a first thrust structure for preventing the transmission shaft from penetrating into the negative pressure cavity.

[0007] In the above-mentioned centrifugal compressor, when in use, after starting to work, the negative pressure chamber is placed in a negative pressure state. By placing the negative pressure chamber in a negative pressure state, the transmission shaft can be prevented from moving in a direction away from the negative pressure chamber. When the negative pressure is too large, the first thrust structure works. When the axial force suddenly increases during use to pull the transmission shaft to move in the direction outside the negative pressure chamber, the negative pressure in the negative pressure chamber will also increase, effectively preventing the transmission shaft from continuing to move outward. In the above-mentioned centrifugal compressor, through the mutual cooperation of the negative pressure chamber and the first thrust structure, the axial position can be well maintained stable to avoid axial movement. At the same time, with negative pressure adsorption, the greater the axial pulling force, the greater the corresponding negative pressure, and the limiting effect is better than the thrust structure. In summary, the centrifugal compressor can effectively solve the problem of poor axial limiting effect of the current transmission shaft.

[0008] In some technical solutions, the second end surface forms a blade to draw air from the negative pressure chamber to the outside.

[0009] In some technical solutions, the second end is provided with an axially extending air guiding channel, and one end port of the air guiding channel extends to the end surface of the second end.

[0010] In some technical schemes, it also includes a mounting tube inserted into the air guide channel from the second end face, the mounting tube forms a tube end wall at one end close to the second end face, an axial through hole is opened in the middle of the tube end wall, an eccentric blade is arranged on the inner side of the tube end wall, and the length of the eccentric blade is greater than the length of the axial through hole.

[0011] In some technical solutions, a second thrust structure is further provided on the transmission shaft, and the blocking direction of the second thrust structure is opposite to the blocking direction of the first thrust structure.

[0012] In some technical schemes, it also includes a cylinder, a rear end cover arranged at one end of the cylinder and a front end cover arranged at the other end of the cylinder, and the power component is arranged in the cylinder; a blind hole facing the cylinder cavity is arranged in the middle of the rear end cover, and the second end extends into the blind hole to form the negative pressure cavity between the blind hole and the bottom of the blind hole; a first bearing for supporting the transmission shaft is arranged in the blind hole, and a second bearing is arranged in the front end cover.

[0013] In some technical solutions, the outlet end of the air guide channel is connected to the cylinder cavity of the cylinder through a radial channel extending radially, and rotational symmetry is formed between each of the radial channels.

[0014] In some technical solutions, a one-way valve is provided in the air guide channel.

[0015] In some technical solutions, the air guide channel is provided with spiral blades to push the gas away from the negative pressure chamber when rotating.

[0016] In order to achieve the second objective, the utility model further provides a mechanical refrigeration system, which includes any one of the centrifugal compressors described above. Since the centrifugal compressors described above have the above technical effects, the mechanical refrigeration system having the centrifugal compressors should also have corresponding technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a centrifugal compressor provided by an embodiment of the utility model;

[0019] Figure 2 A schematic diagram of the structure of another centrifugal compressor provided by an embodiment of the utility model;

[0020] Figure 3 A schematic diagram of the inner structure of the mounting tube provided in an embodiment of the utility model.

[0021] The following are marked in the accompanying drawings:

[0022] Power component 1, transmission shaft 2, centrifugal impeller 3, negative pressure chamber 4, first thrust structure 5, blades 6, air guide channel 7, mounting cylinder 8, eccentric blades 9, axial through hole 10, second thrust structure 11, cylinder body 12, front end cover 13, rear end cover 14, first bearing 15, second bearing 16, radial channel 17. DETAILED DESCRIPTION

[0023] The embodiment of the utility model discloses a centrifugal compressor, which effectively solves the problem that the current axial limiting effect of the transmission shaft is not good.

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] See also Figure 1-Figure 3 , Figure 1 A schematic diagram of the structure of a centrifugal compressor provided by an embodiment of the utility model; Figure 2A schematic diagram of the structure of another centrifugal compressor provided by an embodiment of the utility model; Figure 3 A schematic diagram of the inner structure of the mounting tube provided in an embodiment of the utility model.

[0026] In some examples, a centrifugal compressor is provided. Specifically, the centrifugal compressor mainly includes a power component 1 , a transmission shaft 2 and a centrifugal impeller 3 .

[0027] The transmission shaft 2 passes through the power component 1 to provide rotational power from the power component 1, wherein the power component 1 is generally a motor assembly, which mainly includes a stator and a rotor, wherein the rotor is transmission-connected to the transmission shaft 2. Of course, the power component 1 may also be other structures, such as a hydraulic pump, etc.

[0028] The centrifugal impeller 3 is installed on the transmission shaft 2, and is located in the fan compartment. When the centrifugal impeller 3 rotates with the transmission shaft 2, it can push the fan compartment air body to pressurize the axial air inlet air body to the peripheral air outlet to achieve compression. Since it is the centrifugal impeller 3, the axial air inlet is turned to adjust and export in the tangential direction, so the axial force is transmitted between the centrifugal impeller 3 and the transmission shaft 2. Although the centrifugal impeller 3 can be set oppositely or relatively, it is difficult to completely balance the axial tension.

[0029] In some embodiments, the first end of the transmission shaft 2 is installed with a centrifugal impeller 3, and the second end of the transmission shaft 2 is inserted into the negative pressure chamber 4 so that the end face of the transmission shaft 2 can be in a negative pressure state. Of course, the middle part of the transmission shaft 2 close to the negative pressure chamber 4 can also be provided with a centrifugal impeller 3, so that both ends of the power component are provided with a centrifugal impeller 3. The negative pressure chamber 4 is provided so that the second end of the transmission shaft 2 is subjected to negative pressure, so that under the action of the negative pressure, the transmission shaft 2 can be prevented from escaping from the negative pressure chamber 4.

[0030] It should be noted that the fact that the first end of the transmission shaft 2 is provided with a centrifugal impeller 3 does not mean that when a plurality of centrifugal impellers 3 are provided, each centrifugal impeller 3 is provided at the first end of the transmission shaft 2, and a part of the centrifugal impellers 3 may also be provided at other positions, such as at the middle position, such as between the power component 1 and the negative pressure chamber 4. Of course, it is preferred here that each centrifugal impeller 3 is provided at the first end of the transmission shaft 2.

[0031] The negative pressure in the negative pressure chamber 4 can be maintained by sealing, but the pressure is relatively high. Based on this, an external negative pressure device can be set to connect the negative pressure chamber 4 so that the negative pressure chamber 4 is in a negative pressure state. Of course, the negative pressure chamber 4 can also be achieved by other methods, not limited to the methods listed in the context.

[0032] In some embodiments, the transmission shaft 2 is further provided with a first thrust stop structure 5 for preventing the transmission shaft 2 from penetrating into the negative pressure chamber 4. During operation, the negative pressure of the negative pressure chamber 4 is increased so that the first thrust stop structure 5 is in a stressed state, so as to ensure the stability of the axial position of the transmission shaft 2. Of course, in some embodiments, the transmission shaft 2 may not be prevented from moving in the direction of penetrating into the negative pressure chamber 4.

[0033] In the above-mentioned centrifugal compressor, when in use, after starting to work, the negative pressure chamber 4 is placed in a negative pressure state. By placing the negative pressure chamber 4 in a negative pressure state, the transmission shaft 2 can be prevented from moving in a direction away from the negative pressure chamber 4. When the negative pressure is too large, the first thrust structure 5 works. When the axial force is suddenly increased during application to pull the transmission shaft 2 to move toward the outside of the negative pressure chamber 4, the negative pressure of the negative pressure chamber 4 will also increase, so as to effectively prevent the transmission shaft 2 from continuing to move outward. In the above-mentioned centrifugal compressor, the mutual cooperation between the negative pressure chamber 4 and the first thrust structure 5 can well maintain the stability of the axial position and avoid axial movement. At the same time, with negative pressure adsorption, the greater the axial pulling force, the greater the corresponding negative pressure. Compared with the thrust structure, the limiting effect is better. In summary, the centrifugal compressor can effectively solve the problem of poor axial limiting effect of the current transmission shaft 2.

[0034] In some embodiments, considering that a separately provided negative pressure device is likely to increase the cost, it is preferred that a blade 6 is formed on the second end face to extract air from the negative pressure chamber 4, so that when the transmission shaft 2 rotates, a negative pressure device is formed on the second end face of the transmission shaft 2. As the compressor starts, the transmission shaft 2 rotates, and the negative pressure device is generated, thereby meeting the use needs of the working state. Moreover, as the speed of the transmission shaft 2 increases, the axial tension increases, and the suction force of the corresponding negative pressure device increases. At this time, the negative pressure suction force on the transmission shaft 2 increases, thereby better balancing the axial tension. Moreover, the blade 6 is provided on the end face of the transmission shaft 2, which significantly reduces the cost compared to a separately provided negative pressure device.

[0035] Specifically, the arrangement of the blades 6 on the second end surface can refer to the arrangement of the blades 6 of the centrifugal impeller 3 in the above embodiment, in which case an air outlet channel is arranged on the side wall of the negative pressure chamber 4, and further, a one-way valve is preferably arranged on the air outlet channel. Of course, the blades 6 on the second end surface can also be arranged in other forms.

[0036] In some embodiments, it is preferred that the second end is provided with an axially extending air guide channel 7, and one end port of the air guide channel 7 extends to the second end surface to guide the gas out of the air guide channel 7. It is preferred that the air guide channel 7 is provided with a one-way valve to prevent the gas from flowing in the opposite direction, especially when the axial tension suddenly increases so that the transmission shaft 2 has a tendency to move toward the outside of the negative pressure chamber 4, the one-way valve can play a good protective effect.

[0037] Of course, if attached Figure 1 As shown, when the blades 6 are used, a plurality of the blades 6 can be arranged around the port of the air guide channel 7 to push the gas toward the middle so that the gas can be discharged from the air guide channel 7. The blades 6 can also be called centripetal blades, or arranged in a centripetal impeller structure to push the gas at the periphery toward the center and then discharge it from the air guide channel 7.

[0038] The centripetal blade 6 can make the second end face present a negative pressure state, so that a larger negative pressure area can be obtained to achieve a better negative pressure effect. When the one-way valve is not provided, the cross section of the air guide channel 7 should not be too large.

[0039] In some embodiments, as shown in the attached Figure 2 , 3 As shown, it also includes a mounting tube 8 inserted into the air guide channel 7 from the second end face, and the mounting tube 8 forms a tube end wall at one end close to the second end face, and an axial through hole 10 is opened in the middle of the tube end wall to form a constriction setting, and an eccentric blade 9 is arranged on the inner side of the tube end wall, wherein the length of the eccentric blade 9 is greater than the length of the axial through hole 10. If the cross section of the axial through hole 10 is a circular hole, then the length of the axial through hole 10 is the diameter, and if the cross section of the axial through hole 10 is other shapes, then the length of the axial through hole 10 is the straight-line distance between the two farthest points.

[0040] The eccentric blade 9 can be a foil, which is installed inside the axial through hole 10; the axial through hole 10 is a constricted structure and is used for air intake. When the eccentric blade 9 rotates with the transmission shaft 2, since the eccentric blade 9 does not form a symmetrical structure with the transmission shaft, an eccentric force will be generated, driving the airflow to rotate under the action of the eccentric force, and the constricted structure formed by the axial through hole 10 will help to form a pressure difference inside and outside the axial through hole 10, accelerate the flow of the airflow, and form a negative pressure. After the installation cylinder 8 is set, there is no need to set the above-mentioned blade 6, so that the distance between the second end face and the bottom of the negative pressure chamber 4 is closer, so as to have a better negative pressure adsorption effect.

[0041] In some embodiments, it is preferred that a spiral blade is provided in the guide channel to achieve the effect of pushing the gas axially in the direction away from the negative pressure chamber 4. The spiral blade here can be, for example, a connecting thread, and the specific molding method can refer to the molding method of the connecting thread. Of course, a spiral blade structure can also be adopted, which is loaded into the air guide channel 7 from the second end, and the outer contour is arranged in coordination with the air guide channel 7, and is fixed to the air guide channel 7 by welding, bonding, etc. The structure of the spiral blade can also refer to the spiral conveying channel. By setting the spiral blade, a better suction effect can be achieved, so as to facilitate obtaining a more suitable low pressure. After setting the spiral blade, there is no need to set the above-mentioned blade 6, so that the distance between the second end face and the bottom of the negative pressure chamber 4 is closer, so as to have a better negative pressure adsorption effect.

[0042] In some embodiments, in order to avoid the failure of the negative pressure chamber 4 and the occurrence of a serious accident, a second thrust structure 11 is also provided on the transmission shaft 2, the blocking direction of which is opposite to the blocking direction of the first thrust structure 5. The second thrust structure 11 preferably adopts a thrust bearing. Under normal operation, a certain gap is preferably formed between the second thrust structure 11 and the corresponding limit structure, so that the second thrust structure 11 does not work when the negative pressure chamber 4 does not fail. When the negative pressure fails or cannot work effectively, the transmission shaft 2 moves to the outside of the negative pressure chamber 4 under the action of axial tension after a permitted distance, and then the second thrust structure 11 starts to work.

[0043] In some embodiments, the outlet of the air guide channel 7 generally leads to the power chamber, that is, the cavity where the power component 1 is located. In order to avoid high sealing requirements, it may also include a cylinder 12, a rear end cover 14 arranged at one end of the cylinder 12, and a front end cover 13 arranged at the other end of the cylinder 12, and the power component 1 is arranged in the cylinder 12. The front end cover 13 and the rear end cover 14 are only used for the convenience of distinction, and the reference to "front" and "rear" is used.

[0044] A blind hole facing the cylinder cavity of the cylinder body 12 is provided in the middle of the rear end cover 14, so that when installed, the second end extends into the blind hole to form a negative pressure cavity 4 between the bottom of the blind hole, and the blind hole and the second end need to be matched with high precision in the radial direction to avoid or reduce the flow of gas between each other.

[0045] In order to facilitate supporting the transmission shaft 2 , a first bearing 15 for supporting the transmission shaft 2 is arranged in the blind hole, and a second bearing 16 is arranged in the front end cover 13 .

[0046] In some embodiments, the outlet end of the air guide channel 7 can be connected to the cylinder cavity of the cylinder 12 through a radially extending radial channel 17, wherein rotational symmetry is formed between each of the radial channels 17. However, it is not advisable to set too many radial channels 17, and it is preferred to set only two here.

[0047] Based on the centrifugal compressor provided in the above embodiment, the utility model also provides a mechanical refrigeration system, which includes any one of the centrifugal compressors in the above embodiment. Since the mechanical refrigeration system adopts the centrifugal compressor in the above embodiment, please refer to the above embodiment for the beneficial effects of the mechanical refrigeration system.

[0048] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0049] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A centrifugal compressor, comprising a power component, a transmission shaft and a centrifugal impeller, wherein the transmission shaft passes through the power component so as to be provided with rotational power by the power component, characterized in that: The centrifugal impeller is installed at the first end of the transmission shaft, and the second end of the transmission shaft is inserted into the negative pressure chamber so that the end surface of the transmission shaft can be in a negative pressure state. The transmission shaft is also provided with a first thrust structure for preventing the transmission shaft from penetrating into the negative pressure chamber.

2. The centrifugal compressor according to claim 1, characterized in that: The end surface of the second end forms a blade to draw air from the negative pressure chamber to the outside.

3. The centrifugal compressor according to claim 1, characterized in that: The second end is provided with an axially extending air guiding channel, and one end port of the air guiding channel extends to the end surface of the second end.

4. The centrifugal compressor according to claim 3, characterized in that: It also includes a mounting tube inserted into the air guide channel from the second end face, wherein one end of the mounting tube close to the second end face forms a tube end wall, an axial through hole is provided in the middle of the tube end wall, an eccentric blade is provided on the inner side of the tube end wall, and the length of the eccentric blade is greater than the length of the axial through hole.

5. The centrifugal compressor according to claim 3, characterized in that: The transmission shaft is also provided with a second thrust structure with a blocking direction opposite to that of the first thrust structure.

6. The centrifugal compressor according to claim 3, characterized in that: It also includes a cylinder, a rear end cover arranged at one end of the cylinder and a front end cover arranged at the other end of the cylinder, wherein the power component is arranged in the cylinder; a blind hole facing the cylinder cavity is arranged in the middle of the rear end cover, and the second end extends into the blind hole to form the negative pressure cavity between the blind hole and the bottom of the blind hole; a first bearing for supporting the transmission shaft is arranged in the blind hole, and a second bearing is arranged in the front end cover.

7. The centrifugal compressor according to claim 6, characterized in that: The outlet end of the air guide channel is connected to the cylinder cavity of the cylinder through a radial channel extending radially, and rotational symmetry is formed between the radial channels.

8. The centrifugal compressor according to any one of claims 3 to 7, characterized in that: A one-way valve is arranged at the air guide channel.

9. The centrifugal compressor according to any one of claims 3 to 7, characterized in that: The air guide channel is provided with a spiral blade to push the gas away from the negative pressure chamber when rotating.

10. A mechanical refrigeration system, characterized in that: Comprising a centrifugal compressor as described in any one of claims 1-9.

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