A gas-liquid separator

Abstract

The present invention provides an air-liquid separator, which relates to the technical field of air-conditioning systems, comprising a cylinder, an upper end cover and a lower end cover, the upper end cover and the lower end cover are respectively arranged at the upper and lower ends of the cylinder, and the upper end cover is provided with an inlet and outlet part, the interior of the cylinder is provided with a U-shaped tube connected to the inlet and outlet part, the lower end of one side of the U-shaped tube is provided with an oil return hole, and the oil return hole is covered with a sealing bin, rubber blocks are movably provided on both sides of the sealing bin, and nut sleeves are rotatably provided on both sides of the sealing bin through bearings, screw shafts are provided on the outer sides of the two groups of rubber blocks, and the two groups of screw shafts respectively pass through the nut sleeves on both sides; the present invention drives the nut sleeve to rotate by driving the gear part, and utilizes the adaptation effect of the thread to drive the screw shaft to move, so that the rubber block moves inside the sealing bin, the rubber blocks on both sides move, and the covering distance of the oil return hole is adjusted, thereby adjusting the size of the oil return hole, which is conducive to adapting to different compressor needs and has a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of air-conditioning systems, and in particular to a gas-liquid separator. Background Art

[0002] In air conditioning systems, an intermediate heat exchanger is often used to exchange heat between the low-temperature refrigerant from the evaporator and the high-temperature refrigerant from the cooler, so as to increase the temperature of the refrigerant entering the compressor and reduce the temperature of the refrigerant before throttling, thereby improving the cooling efficiency of the heat exchanger. Generally, most compressors can only compress gaseous refrigerant. If liquid refrigerant enters the compressor, it will cause liquid hammer and damage the compressor. In order to avoid compressor liquid hammer, a gas-liquid separator needs to be installed before the compressor. In related technologies, gas-liquid separation is performed on the refrigerant before entering the compressor.

[0003] The gas-liquid separator basically separates the refrigerant returning from the evaporator to the compressor into gas and liquid, allowing only the gas to return to the compressor. However, the separated and accumulated liquid refrigerant will dissolve in oil, so it is necessary to return the oil to the compressor to ensure the oil volume in the compressor and the oil supply to the scroll part. In order to return the oil, the outlet pipe of the gas-liquid separator is designed to be a curved shape that leads to the bottom of the gas-liquid separator, and then an oil return hole is designed on the side of the curved part to allow the liquid refrigerant with oil to return to the compressor. In the use requirements of different compressors, the oil return will be better if the oil return hole is larger, but the reflux of liquid refrigerant will also increase, resulting in the dilution of the oil (the lubricating effect of the oil). The vortex part will be abnormally worn, and the compressor may malfunction. If the oil return hole is small, the amount of liquid refrigerant returning will be reduced, but because the return oil is also reduced, the oil supply in the machine will be insufficient. Due to the insufficient oil supply to the vortex part, abnormal wear will occur, which will cause the compressor to malfunction. Therefore, according to different compressor needs, the oil return hole diameter must ensure the oil amount in the compressor and suppress the reflux of liquid refrigerant to reach below the oil dilution requirement. It is necessary to have a suitable hole diameter, and the existing gas-liquid separator oil return holes are mostly fixed in diameter and cannot be adjusted according to actual needs. Therefore, the present invention proposes a gas-liquid separator to solve the problems existing in the prior art. Summary of the Invention

[0004] In response to the above problems, the present invention proposes a gas-liquid separator, which can adjust the size of the oil return hole, is conducive to adapting to different compressor needs, and has a wide range of applications.

[0005] To achieve the purpose of the present invention, the present invention is implemented through the following technical solutions: a gas-liquid separator, comprising a cylinder, an upper end cover and a lower end cover, the upper end cover and the lower end cover are respectively arranged at the upper and lower ends of the cylinder, and the upper end cover is provided with an inlet and outlet portion, a U-shaped tube connected to the inlet and outlet portion is provided inside the cylinder, an oil return hole is provided at the lower end of one side of the U-shaped tube, and a sealing chamber is provided on the oil return hole cover, rubber blocks are movably provided on both sides of the sealing chamber, and nut sleeves are rotatably provided on both sides of the sealing chamber through bearings, screw shafts are provided on the outer sides of two groups of rubber blocks, and the two groups of screw shafts respectively penetrate the nut sleeves on both sides, and the screw shafts are threadedly adapted to the nut sleeves;

[0006] A base frame is provided at the bottom of the interior of the lower end cover, and a driving gear portion is provided on the base frame. The driving gear portion is used to drive the nut sleeve to rotate.

[0007] Further improvements are: the driving gear part includes a gear plate, a first gear and a second gear, the gear plate is rotatably arranged at the middle end of the bottom of the base frame, the first gear is provided with two groups, and the two groups of the first gears are rotatably arranged on both sides of the bottom of the inner wall of the base frame respectively, and the gear plate is adapted to the first gear.

[0008] Further improvements are: the second gear is rotatably arranged on both sides of the base frame, and multiple groups of the second gears on both sides are equidistantly arranged, a first bevel gear is provided on the first gear, and a second bevel gear adapted to the first bevel gear is provided on one side of the second gear at the lower end, meshing teeth are provided on the outer side of the nut sleeve, and the second gear at the upper end is adapted to the meshing teeth.

[0009] A further improvement is that a rotary handle is rotatably provided at the bottom of the lower end cover, and the upper end of the rotary handle passes through the lower end cover and is connected to the gear disk, and a sealing shaft ring is provided at the penetration of the rotary handle and the lower end cover.

[0010] A further improvement is that a guide rod is connected to the screw shaft, and the guide rod passes through the sealing bin and is connected to the rubber block.

[0011] Further improvements are: a sealing member is provided at the front end of the sealing bin, and rubber blocks are attached to the sealing member and the two sides of the inside of the sealing bin. The front end of the sealing member is connected to a filter cartridge, and filter holes are provided on the outside of the filter cartridge. The front end of the filter cartridge is a transparent area, and the transparent area is used to display the oil return hole. The lower end of the outer side of the cylinder is transparent.

[0012] A further improvement is that a reinforcement plate is provided below the rear end of the U-shaped tube, and the reinforcement plate is fixed to the cylinder.

[0013] Further improvements are: the inlet and outlet parts include an air inlet pipe and an air outlet pipe, the air outlet pipe is connected to the output end of the U-shaped tube, a flow guide is provided on one side of the top inside the upper end cover, the air inlet pipe is connected to the flow guide, and the flow guide is staggered with the output end of the U-shaped tube, the air outlet pipe, the output end of the U-shaped tube and the upper end cover are fixed by argon arc spot welding, and the air inlet pipe and the flow guide are respectively fixed to the upper end cover by argon arc spot welding.

[0014] A further improvement is that a mounting plate is provided at the bottom of the lower end cover, and a mounting hole is provided on the mounting plate, and the upper end cover, the cylinder and the lower end cover are fixed by CO welding.

[0015] Further improvements are: an intake pipe is connected to the upper side of the output end of the U-shaped tube, and the lower end of the intake pipe is lower than the oil return hole. A ball valve is provided on the intake pipe, and the adjusting end of the ball valve passes through the cylinder body, and a sealing bearing is provided at the penetration point. The adjusting end of the ball valve is connected to a knob.

[0016] The beneficial effects of the present invention are:

[0017] 1. The present invention drives the nut sleeve to rotate by driving the gear part, and utilizes the adaptation effect of the thread to drive the screw shaft to move, so that the rubber block moves inside the sealing chamber. The rubber blocks on both sides move to adjust the covering distance of the oil return hole, thereby adjusting the size of the oil return hole, which is conducive to adapting to different compressor needs and has a wide range of applications.

[0018] 2. The present invention fixes the outlet pipe, the output end of the U-shaped pipe and the upper end cover by argon arc spot welding, and fixes the inlet pipe and the guide piece to the upper end cover respectively by argon arc spot welding. Argon arc spot welding is used instead of traditional flame brazing, which reduces energy consumption, improves the safety production coefficient, reduces production costs, reduces safety hazards and improves quality.

[0019] 3. The present invention can add an air intake pipe as needed, and use the air intake pipe to extract liquid refrigerant from the bottom of the cylinder structure and gasify it, so that the lubricating oil can quickly return from the oil return hole, which has the effect of improving the lubrication effect of the compressor when it is working. It can be closed by a ball valve when not in use, and has diversified functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the front view of the present invention;

[0021] Figure 2 It is an internal schematic diagram of the present invention;

[0022] Figure 3 This is a schematic diagram of the interior of the sealed warehouse of the present invention;

[0023] Figure 4 Schematic diagram of the intake pipe of the present invention.

[0024] Among them: 1. Cylinder body; 2. Upper end cover; 3. Lower end cover; 4. U-shaped tube; 5. Oil return hole; 6. Sealing chamber; 7. Rubber block; 8. Bearing; 9. Nut sleeve; 10. Screw shaft; 11. Base frame; 12. Sprocket; 13. First gear; 14. Second gear; 15. First bevel gear; 16. Second bevel gear; 17. Turning handle; 18. Guide rod; 19. Seal; 20. Filter cartridge; 21. Reinforcement plate; 22. Inlet pipe; 23. Outlet pipe; 24. Guide piece; 25. Mounting plate; 26. Mounting hole; 27. Intake pipe; 28. Ball valve; 29. Sealing bearing; 30. Knob. DETAILED DESCRIPTION

[0025] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Example 1

[0026] according to Figure 1 、 2 As shown in Figures 3 and 4, this embodiment proposes a gas-liquid separator, comprising a cylinder 1, an upper end cover 2 and a lower end cover 3, wherein the upper end cover 2 and the lower end cover 3 are respectively arranged at the upper and lower ends of the cylinder 1, and the upper end cover 2 is provided with an inlet and outlet portion, the interior of the cylinder 1 is provided with a U-shaped tube 4 connected to the inlet and outlet portion, the lower end of one side of the U-shaped tube 4 is provided with an oil return hole 5, and the oil return hole 5 is covered with a sealing bin 6, both sides of the sealing bin 6 are movably provided with rubber blocks 7, and both sides of the sealing bin 6 are rotatably provided with nut sleeves 9 through bearings 8, the outer sides of the two groups of rubber blocks 7 are provided with screw shafts 10, and the two groups of screw shafts 10 respectively penetrate the nut sleeves 9 on both sides, and the screw shafts 10 are threadedly adapted to the nut sleeves 9;

[0027] A base frame 11 is provided at the bottom of the interior of the lower end cover 3, and a driving gear portion is provided on the base frame 11. The driving gear portion is used to rotate the nut sleeve 9. During use, the driving gear portion drives the nut sleeve 9 to rotate, and the screw shaft 10 is driven to move by the adaptability of the thread, thereby causing the rubber block 7 to move inside the sealing chamber 6. The rubber blocks 7 on both sides move to adjust the covering distance of the oil return hole 5, thereby adjusting the size of the oil return hole 5, which is conducive to adapting to different compressor needs.

[0028] The driving gear unit includes a toothed disc 12, a first gear 13, and a second gear 14. The toothed disc 12 is rotatably mounted at the middle end of the bottom of the base frame 11. Two sets of first gears 13 are provided, and the two sets of first gears 13 are rotatably mounted on both sides of the bottom of the inner wall of the base frame 11. The toothed disc 12 is adapted to the first gear 13. The second gear 14 is rotatably mounted on both sides of the base frame 11, and multiple sets of second gears 14 are equidistantly mounted on both sides. A first bevel gear 15 is provided on the first gear 13, and a second bevel gear 16 adapted to the first bevel gear 15 is provided on one side of the second gear 14 at the lower end. The outer side of the nut sleeve 9 is provided with meshing teeth, and the second gear 14 at the upper end is adapted to the meshing teeth. A rotary knob 17 is rotatably mounted at the bottom of the lower end cover 3, and the upper end of the rotary knob 17 passes through the lower end cover 3 and is connected to the toothed disc 12. A sealing shaft ring is provided at the intersection of the rotary knob 17 and the lower end cover 3. When in use, rotating the handle 17 drives the toothed disc 12 to rotate, and the toothed disc 12 drives the first gear to rotate 13, and the second gear 14 is driven to rotate through the adaptation of the first bevel gear 15 and the second bevel gear 16. The second gear 14 at the upper end drives the nut sleeve 9 to rotate through the meshing teeth, and utilizes the adaptation of the thread to drive the screw shaft 10 to move, so that the rubber block 7 moves inside the sealing chamber 6. The rubber blocks 7 on both sides move to adjust the covering distance of the oil return hole 5, thereby adjusting the size of the oil return hole 5, which is conducive to adapting to different compressor needs.

[0029] The screw shaft 10 is connected to a guide rod 18, which passes through the sealing chamber 6 and is connected to the rubber block 7. When in use, the nut sleeve 9 is rotated by the driving gear portion, and the screw shaft 10 is driven to move by the adaptation of the thread, and the guiding effect of the guide rod 18 is cooperated with the guiding effect of the guide rod 18, so that the rubber block 7 moves inside the sealing chamber 6.

[0030] The front end of the sealing chamber 6 is provided with a sealing member 19, and the sealing member 19 and the rubber blocks 7 are attached to both sides of the sealing chamber 6. The front end of the sealing member 19 is connected to the filter cartridge 20, and the outer side of the filter cartridge 20 is provided with filter holes to facilitate filtering of the returning lubricating oil. The front end of the filter cartridge 20 is a transparent area, and the transparent area is used to display the oil return hole 5. The lower end of the outer side of the cylinder body 1 is transparent. This facilitates observation of the oil return hole 5 for adjustment.

[0031] A reinforcing plate 21 is provided below the rear end of the U-shaped tube 4, and the reinforcing plate 21 is fixed to the cylinder 1. The reinforcing plate 21 is beneficial to fixing the U-shaped tube 4, making the U-shaped tube 4 more stable.

[0032] The inlet and outlet portion includes an air inlet pipe 22 and an air outlet pipe 23. The air outlet pipe 23 is connected to the output end of the U-shaped tube 4. A flow guide 24 is provided on one side of the top of the upper end cover 2. The air inlet pipe 22 is connected to the flow guide 24, and the flow guide 24 is staggered with the output end of the U-shaped tube 4. The air outlet pipe 23, the output end of the U-shaped tube 4, and the upper end cover 2 are fixed by argon arc spot welding. The air inlet pipe 22 and the flow guide 24 are also fixed to the upper end cover 2 by argon arc spot welding. The bottom of the lower end cover 3 is provided with a mounting plate 25, and the mounting plate 25 is provided with a mounting hole 26. The upper end cover 2, the cylinder 1, and the lower end cover 3 are fixed by CO2 welding. The present invention fixes the outlet pipe 23, the output end of the U-shaped tube 4 and the upper end cover 2 by argon arc spot welding, and fixes the inlet pipe 22 and the guide member 24 to the upper end cover 2 by argon arc spot welding respectively. Argon arc spot welding is used instead of traditional flame brazing, which reduces energy consumption, improves the safety production coefficient, reduces production costs, reduces safety hazards, and improves quality. Example 2

[0033] according to Figure 1 、 2 As shown in Figures 3 and 4, this embodiment proposes a gas-liquid separator, comprising a cylinder 1, an upper end cover 2 and a lower end cover 3, wherein the upper end cover 2 and the lower end cover 3 are respectively arranged at the upper and lower ends of the cylinder 1, and the upper end cover 2 is provided with an inlet and outlet portion, the interior of the cylinder 1 is provided with a U-shaped tube 4 connected to the inlet and outlet portion, the lower end of one side of the U-shaped tube 4 is provided with an oil return hole 5, and the oil return hole 5 is covered with a sealing bin 6, rubber blocks 7 are movably provided on both sides of the sealing bin 6, and nut sleeves 9 are rotatably provided on both sides of the sealing bin 6 through bearings 8, screw shafts 10 are provided on the outer sides of the two groups of rubber blocks 7, and the two groups of screw shafts 10 respectively penetrate the nut sleeves 9 on both sides, and the screw shafts 10 are threadedly adapted to the nut sleeves 9;

[0034] A base frame 11 is provided at the bottom of the interior of the lower end cover 3, and a driving gear portion is provided on the base frame 11. The driving gear portion is used to rotate the nut sleeve 9. During use, the driving gear portion drives the nut sleeve 9 to rotate, and the screw shaft 10 is driven to move by the adaptability of the thread, thereby causing the rubber block 7 to move inside the sealing chamber 6. The rubber blocks 7 on both sides move to adjust the covering distance of the oil return hole 5, thereby adjusting the size of the oil return hole 5, which is conducive to adapting to different compressor needs.

[0035] A reinforcing plate 21 is provided below the rear end of the U-shaped tube 4, and the reinforcing plate 21 is fixed to the cylinder 1. The reinforcing plate 21 is beneficial to fixing the U-shaped tube 4, making the U-shaped tube 4 more stable.

[0036] An air intake pipe 27 is connected to the upper side of the output end of the U-shaped tube 4, and the lower end of the air intake pipe 27 is lower than the oil return hole 5. A ball valve 28 is provided on the air intake pipe 27. The regulating end of the ball valve 28 passes through the cylinder 1, and a sealing bearing 29 is provided at the penetration point to prevent air leakage. The regulating end of the ball valve 28 is connected to a knob 30. The lower end of the suction pipe 27 is lower than the oil return hole 5. When the compressor is working, a pressure difference is generated between the U-shaped tube 4 and the suction pipe 27, extracting the liquid refrigerant at the inlet of the suction pipe 27. The extracted liquid refrigerant can be converted into gaseous refrigerant when discharged to the outlet pipe 23. The liquid refrigerant and lubricating oil accumulate at the bottom of the cylinder 1, while the gas is located at the top of the cylinder 1 and is absorbed by the air inlet of the U-shaped tube 4. The specific gravity of the lubricating oil is less than that of the liquid refrigerant, so that the liquid refrigerant is located below the lubricating oil. When the suction pipe 27 extracts the liquid refrigerant, the liquid level of the lubricating oil drops, and the lubricating oil can flow back into the U-shaped tube 4 through the oil return hole 5, thereby accelerating the return of the lubricating oil. When not in use, it can be closed by the ball valve 28. The ball valve 28 is a prior art. By rotating the knob 30, the valve core inside the ball valve 28 is driven to open or close.

[0037] Verification example:

[0038] Whether the adjusted diameter of the experimental oil return hole 5 is appropriate can be determined by measuring whether the difference between the temperature of the compressor bottom (oil temperature) and the evaporation temperature under various operating conditions meets the standard.

[0039] The gas-liquid separator rotates the nut sleeve 9 via a driving gear, which, through the adaptability of the threads, drives the screw shaft 10 to move, thereby causing the rubber block 7 to move within the sealing chamber 6. The rubber blocks 7 on both sides move, adjusting the distance of coverage of the oil return hole 5, thereby adjusting the size of the oil return hole 5. This facilitates adaptation to different compressor needs and has a wide range of applications. Furthermore, the present invention secures the outlet pipe 23 and the output end of the U-shaped tube 4 to the upper end cover 2 via argon arc spot welding, and secures the inlet pipe 22 and the flow guide 24 to the upper end cover 2 via argon arc spot welding. Using argon arc spot welding instead of traditional flame brazing reduces energy consumption, improves production safety, lowers production costs, reduces safety hazards, and improves quality. Furthermore, the present invention can add an intake pipe 27 as needed. This intake pipe 27 extracts liquid refrigerant from the bottom of the cylinder 1 structure and vaporizes it, allowing lubricating oil to quickly return from the oil return hole 5, thereby improving the lubrication effect of the compressor during operation. When not in use, the air can be closed via a ball valve 28, providing diverse functions.

[0040] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A gas-liquid separator, comprising a cylinder (1), an upper end cover (2) and a lower end cover (3), characterized in that: The upper end cover (2) and the lower end cover (3) are respectively arranged at the upper and lower ends of the cylinder (1), and the upper end cover (2) is provided with an inlet and outlet portion. The interior of the cylinder (1) is provided with a U-shaped tube (4) connected to the inlet and outlet portion. The lower end of one side of the U-shaped tube (4) is provided with an oil return hole (5), and the oil return hole (5) is covered with a sealing chamber (6). Rubber blocks (7) are movably provided on both sides of the sealing chamber (6), and nut sleeves (9) are rotatably provided on both sides of the sealing chamber (6) through bearings (8). Screw shafts (10) are provided on the outer sides of the two groups of rubber blocks (7), and the two groups of screw shafts (10) respectively penetrate the nut sleeves (9) on both sides, and the screw shafts (10) are threadably adapted to the nut sleeves (9). A base frame (11) is provided at the bottom of the interior of the lower end cover (3), and a driving gear portion is provided on the base frame (11), and the driving gear portion is used to drive the nut sleeve (9) to rotate; The front end of the sealing chamber (6) is provided with a sealing member (19), and the sealing member (19) and the two sides of the sealing chamber (6) are bonded with rubber blocks (7). The front end of the sealing member (19) is connected to a filter cartridge (20), and the outer side of the filter cartridge (20) is provided with a filter hole. The front end of the filter cartridge (20) is a transparent area, and the transparent area is used to display the oil return hole (5). The lower end of the outer side of the cylinder (1) is transparent.

2. A gas-liquid separator according to claim 1, characterized in that: The driving gear portion comprises a toothed disc (12), a first gear (13) and a second gear (14); the toothed disc (12) is rotatably arranged at the middle end of the bottom of the base frame (11); two groups of the first gears (13) are provided, and the two groups of the first gears (13) are rotatably arranged at both sides of the bottom of the inner wall of the base frame (11); the toothed disc (12) and the first gear (13) are adapted to each other.

3. A gas-liquid separator according to claim 2, characterized in that: The second gear (14) is rotatably arranged on both sides of the base frame (11), and multiple groups of the second gears (14) on both sides are equidistantly arranged. A first bevel gear (15) is provided on the first gear (13), and a second bevel gear (16) adapted to the first bevel gear (15) is provided on one side of the second gear (14) at the lower end. The outer side of the nut sleeve (9) is provided with meshing teeth, and the second gear (14) at the upper end is adapted to the meshing teeth.

4. A gas-liquid separator according to claim 3, characterized in that: The bottom of the lower end cover (3) is rotatably provided with a rotary handle (17), and the upper end of the rotary handle (17) penetrates the lower end cover (3) and is connected to the toothed disc (12), and a sealing shaft ring is provided at the penetration point between the rotary handle (17) and the lower end cover (3).

5. A gas-liquid separator according to claim 4, characterized in that: A guide rod (18) is connected to the screw shaft (10), and the guide rod (18) passes through the sealing chamber (6) and is connected to the rubber block (7).

6. The gas-liquid separator according to claim 1, characterized in that: A reinforcing plate (21) is provided below the rear end of the U-shaped tube (4), and the reinforcing plate (21) is fixed to the cylinder (1).

7. The gas-liquid separator according to claim 1, characterized in that: The inlet and outlet portion comprises an air inlet pipe (22) and an air outlet pipe (23), the air outlet pipe (23) being in communication with the output end of the U-shaped tube (4), a flow guide (24) being provided on one side of the top of the interior of the upper end cover (2), the air inlet pipe (22) being in communication with the flow guide (24), and the flow guide (24) being staggered with the output end of the U-shaped tube (4), the air outlet pipe (23), the output end of the U-shaped tube (4) and the upper end cover (2) being fixed by argon arc spot welding, and the air inlet pipe (22) and the flow guide (24) being fixed to the upper end cover (2) by argon arc spot welding.

8. The gas-liquid separator according to claim 7, characterized in that: A mounting plate (25) is provided at the bottom of the lower end cover (3), and a mounting hole (26) is provided on the mounting plate (25). The upper end cover (2), the cylinder (1) and the lower end cover (3) are fixed by CO2 welding.

9. A gas-liquid separator according to any one of claims 1 to 8, characterized in that: An air intake pipe (27) is connected to the upper side of the output end of the U-shaped tube (4), and the lower end of the air intake pipe (27) is lower than the oil return hole (5). A ball valve (28) is provided on the air intake pipe (27). The regulating end of the ball valve (28) passes through the cylinder (1), and a sealing bearing (29) is provided at the penetration point. The regulating end of the ball valve (28) is connected to a knob (30).

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