Centrifugal water pump heat dissipation structure

Abstract

The utility model provides a centrifugal water pump heat dissipation structure, including pump head, impeller, rotation drive component and heat dissipation fan wheel, be equipped with the containing space and the water inlet and water outlet who respectively with the containing space intercommunication in the pump head, the impeller sets up in the containing space, the output of rotation drive component penetrates into the containing space and is connected with the impeller, heat dissipation fan wheel is set up on the output of rotation drive component, and heat dissipation fan wheel is located between pump head and rotation drive component, by rotation drive component drive impeller together with heat dissipation fan wheel rotates, make heat dissipation fan wheel to rotation drive component blow -off heat dissipation simultaneously, take away the heat that pump head conduction to rotation drive component's direction, the utility model discloses heat dissipation fan wheel to rotation drive component blow -off heat dissipation, simultaneously, still intercepts and took away the heat that passed through the axial direction of the drive end of rotation drive component from pump head, guarantee even under hot water working condition also can have better heat dissipation effect, and can effectively reduce cost.

Description

Technical Field

[0001] This utility model relates to the field of water pump technology, and in particular to a heat dissipation structure for a centrifugal water pump. Background Technology

[0002] Centrifugal water pumps, as an indispensable core component of dishwashers, are seeing their market demand continue to rise as the dishwasher industry matures and becomes more widespread. To achieve cost reduction and efficiency improvement in the face of fierce market competition, one common strategy adopted by manufacturers is to optimize motor design by reducing the amount of materials used in the motor. However, reducing the amount of materials used in the motor inevitably brings a significant side effect: the heat generated by the motor during operation relatively increases, leading to a greater overall heat output from the motor.

[0003] To address the issue of increased overall heat generation in motors, the current mainstream and typical solution in the industry is to add a heat dissipation structure at the rear of the motor (excluding the pump head). This heat dissipation structure typically consists of a retaining ring, impeller, fan cover, and screws. However, this heat dissipation structure solution has the following problems: First, the scalability of this heat dissipation structure is poor. It is not an independent standard part, and its design (such as impeller size, fan shape, and mounting hole position) must be strictly matched and developed with the size, speed and heat dissipation requirements of a specific motor model. This means that when each motor or pump model changes, the heat dissipation structure often needs to be redesigned or adjusted, which greatly limits its versatility and the flexibility of product series expansion. Second, the heat dissipation efficiency of this heat dissipation structure drops significantly under certain operating conditions. Specifically, in the actual operation of a dishwasher, the centrifugal water pump often needs to handle high-temperature washing water or rinsing water. When the medium flowing in the pump head is hot water, heat will be continuously conducted from the pump head end to the motor through the pump shaft (as a heat conduction path). This additional heat input from the working medium seriously interferes with the heat dissipation effect of the tail heat dissipation structure. The heat dissipation structure, which was originally used to dissipate the heat generated by the motor itself, now needs to additionally resist the heat conducted in through the shaft, resulting in a significant reduction in the heat dissipation efficiency of the entire heat dissipation system, and the motor may still face the risk of overheating.

[0004] Therefore, it is necessary to provide a centrifugal water pump heat dissipation structure to further reduce costs while ensuring good heat dissipation even under hot water conditions. Utility Model Content

[0005] The purpose of this invention is to provide a centrifugal water pump heat dissipation structure to further reduce costs while ensuring good heat dissipation even in hot water conditions.

[0006] To achieve the above objectives, this utility model provides a centrifugal water pump heat dissipation structure, including a pump head, an impeller, a rotary drive assembly, and a cooling fan. The pump head has a receiving space and an inlet and an outlet respectively communicating with the receiving space. The impeller is disposed within the receiving space. The output end of the rotary drive assembly passes through the receiving space and is connected to the impeller. The cooling fan is sleeved on the output end of the rotary drive assembly and is located between the pump head and the rotary drive assembly. The rotary drive assembly drives the impeller and the cooling fan to rotate together, so that the cooling fan blows air to dissipate heat from the rotary drive assembly while carrying away the heat conducted from the pump head toward the rotary drive assembly.

[0007] Preferably, the pump head includes an upper volute and a bottom shell, the upper volute and the bottom shell are fixedly connected, the upper volute and the bottom shell surround the receiving space, the water inlet and the water outlet are respectively disposed on the upper volute; the output end of the rotary drive assembly passes through the bottom shell and is inserted into the receiving space. Preferably, the bottom surface of the bottom shell facing the heat dissipation fan is provided with a recessed structure that is recessed inward relative to its center and edge. The recessed structure is provided with a plurality of reinforcing ribs connecting the center and edge of the heat dissipation fan. The reinforcing ribs divide the recessed structure into a plurality of partition grooves. Preferably, the recessed structure is annular, and the reinforcing ribs are arranged at intervals along the same circumferential direction within the recessed structure. Preferably, the rotary drive assembly includes a motor and a pump shaft, the output end of the motor is connected to the pump shaft, the pump shaft passes through the accommodating space and is connected to the impeller, and the cooling fan is sleeved on the pump shaft. Preferably, the rotary drive assembly further includes a mounting frame, on which the motor is mounted, and the mounting frame is fixedly connected to the pump head. Preferably, a first airflow gap is formed between the top surface of the cooling fan and the bottom surface of the pump head, and a second airflow gap is formed between the bottom surface of the cooling fan and the upper part of the rotary drive assembly. The pump head, the cooling fan, and the rotary drive assembly are respectively connected to the first airflow gap and the second airflow gap in the outer peripheral direction. A cooling air duct is provided in the middle of the cooling fan, which connects the first airflow gap and the second airflow gap. When the rotary drive assembly drives the cooling fan to rotate, the airflow enters the first airflow gap from the outside and flows along the outer side of the rotary drive assembly in sequence through the cooling air duct and the second airflow gap. Preferably, the cooling fan wheel includes a fan blade outer shell, an intermediate connecting part, and a fan blade body connected sequentially in its radial direction. The bottom of the fan blade outer shell is provided with a groove, and the middle part of the fan blade outer shell is provided with a through hole communicating with the groove. A first airflow gap is formed between the top surface of the fan blade outer shell and the bottom surface of the pump head, and a second airflow gap is formed between the bottom surface of the fan blade outer shell and the upper part of the rotary drive assembly. The intermediate connecting part is disposed in the groove and located directly opposite the through hole. The fan blade body is disposed in the groove and inserted into the through hole. A plurality of fan blade bodies are respectively connected between the inner wall of the through hole and the intermediate connecting part in a circumferential direction. A plurality of cooling air ducts are respectively formed between two adjacent fan blade bodies. Preferably, the cooling fan wheel further includes an air guide section, and the air guide section is provided between each of the two adjacent fan blade bodies. The air guide section extends from the upper part of the intermediate connecting part along the radial direction of the cooling fan wheel toward the bottom of the fan blade body. Preferably, the end of the fan blade body connected to the through hole is provided with a fan blade extension that extends along the radial direction of the heat dissipation fan wheel and along the bottom surface of the groove to the inner wall of the groove. Compared with existing technologies, the centrifugal water pump heat dissipation structure of this utility model places the heat dissipation fan between the rotary drive assembly and the pump head, and the heat dissipation fan is sleeved on the output end of the rotary drive assembly. Therefore, while the rotary drive assembly drives the impeller inside the pump head to rotate, it also drives the heat dissipation fan to rotate together. This allows the heat dissipation fan to blow air onto the rotary drive assembly for heat dissipation. At the same time, it actively intercepts and carries away the heat conducted axially from the pump head through the drive end of the rotary drive assembly, dissipating the heat before it invades the rotary drive assembly in large quantities. This effectively solves the core problem of reduced heat dissipation efficiency caused by axial heat transfer in existing technologies, significantly improving the heat dissipation efficiency when the centrifugal water pump is delivering hot water, ensuring good heat dissipation even in hot water conditions. Secondly, the heat dissipation fan is directly integrated on the drive end of the rotary drive assembly on the pump head side. Utilizing the same shaft and rotational power source as the impeller, it completely eliminates the need for the retaining ring, independent fan cover, and additional fastening screws required by traditional tail heat dissipation structures, effectively further reducing costs. At the same time, it simplifies the manufacturing and assembly process and reduces the number of steps. Furthermore, the cooling fan of this invention is directly mounted on the drive end of the rotary drive assembly on the pump head side. The shape and structure of the cooling fan are basically unrelated to the tail of the motor. This makes the cooling solution easier to adapt to rotary drive assemblies (motors) of different models or sources. It is only necessary to ensure that the interface at the drive end of the rotary drive assembly on the pump head side is compatible, which greatly improves the versatility of the design and the scalability of the product series. Attached Figure Description

[0008] Figure 1This is a three-dimensional structural diagram of the centrifugal water pump heat dissipation structure of this utility model.

[0009] Figure 2 This is an exploded view of the heat dissipation structure of the centrifugal water pump of this utility model.

[0010] Figure 3 This is a top view of the heat dissipation structure of the centrifugal water pump of this utility model.

[0011] Figure 4 It is along Figure 3 A cross-sectional view along the AA direction.

[0012] Figure 5 yes Figure 4 The diagram shows the airflow direction for heat dissipation when the rotary drive assembly drives the impeller and the cooling fan to rotate together.

[0013] Figure 6 This is a three-dimensional structural diagram of the heat dissipation fan wheel of this utility model.

[0014] Figure 7 This is a three-dimensional structural diagram of the heat dissipation fan wheel of this utility model from another angle. Detailed Implementation

[0015] To explain in detail the technical content, structural features, objectives and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0016] Please see Figures 1 to 4 The centrifugal water pump heat dissipation structure 100 of this utility model includes a pump head 1, an impeller 2, a rotary drive assembly 3, and a heat dissipation fan 4. The pump head 1 is provided with a receiving space 11 and an inlet 12 and an outlet 13 respectively connected to the receiving space 11. The impeller 2 is disposed in the receiving space 11. The output end of the rotary drive assembly 3 passes through the receiving space 11 and is connected to the impeller 2. The heat dissipation fan 4 is sleeved on the output end of the rotary drive assembly 3 and is located between the pump head 1 and the rotary drive assembly 3. The rotary drive assembly 3 drives the impeller 2 and the heat dissipation fan 4 to rotate together, so that the heat dissipation fan 4 blows air to the rotary drive assembly 3 to dissipate heat and removes the heat conducted from the pump head 1 toward the rotary drive assembly 3.

[0017] This invention places the cooling fan 4 between the rotary drive assembly 3 and the pump head 1, and the cooling fan 4 is sleeved on the output end of the rotary drive assembly 3. Therefore, when the rotary drive assembly 3 drives the impeller 2 inside the pump head 1 to rotate, it will also drive the cooling fan 4 to rotate together. This allows the cooling fan 4 to blow air to the rotary drive assembly 3 for heat dissipation. At the same time, it also actively intercepts and carries away the heat conducted from the pump head 1 through the drive end of the rotary drive assembly 3 in the axial direction, dissipating the heat before it enters the rotary drive assembly 3 in large quantities. This effectively solves the core problem of reduced heat dissipation efficiency caused by axial heat transfer in the prior art, and significantly improves the heat dissipation performance when the centrifugal water pump is delivering hot water.

[0018] Please see Figure 1 and Figure 4 In one embodiment, the pump head 1 includes an upper volute 14 and a bottom shell 15, which are fixedly connected. The upper volute 14 and the bottom shell 15 enclose a receiving space 11. An inlet 12 and an outlet 13 are respectively disposed on the upper volute 14. The output end of the rotary drive assembly 3 passes through the bottom shell 15 and is inserted into the receiving space 11. When the rotary drive assembly 3 drives the impeller 2 to rotate, the water entering the receiving space 11 from the direction of the inlet 12 is thrown towards the outer edge of the impeller 2 under the action of centrifugal force and then discharged through the outlet 13. However, the structure of the pump head 1 is not limited to this.

[0019] Please see Figure 2 and Figure 4 In one embodiment, the bottom surface of the bottom shell 15 facing the heat dissipation fan 4 is provided with a recessed structure 151 that is recessed inwards from its center and edges. The recessed structure 151 contains several reinforcing ribs 152 connected between the center and edge of the heat dissipation fan 4, and the reinforcing ribs 152 divide the recessed structure 151 into several partition grooves 153. By setting the bottom surface of the bottom shell 15 as a recessed structure 151, production costs are effectively reduced. By providing the reinforcing ribs 152, the structural strength of the bottom shell 15 of the pump head 1 is effectively improved, allowing the pump head 1 to effectively resist the water flow impact generated by the impeller 2 during operation, effectively ensuring the stability of the entire structure. Furthermore, since the reinforcing ribs 152 divide the recessed structure 151 into several partition grooves 153, it helps to accommodate more airflow, so that when the rotary drive assembly 3 drives the impeller 2 and the heat dissipation fan 4 to rotate together, the heat dissipation fan 4 generates more airflow, further improving the heat dissipation effect.

[0020] Furthermore, the recessed structure 151 is a ring structure, and the reinforcing ribs 152 are arranged at intervals along the same circumferential direction within the recessed structure 151. However, this is not a limitation.

[0021] Please see Figures 1 to 4In one embodiment, the rotary drive assembly 3 includes a motor 31 and a pump shaft 32. The output end of the motor 31 is connected to the pump shaft 32, which passes through the accommodating space 11 and is connected to the impeller 2. A cooling fan 4 is sleeved on the pump shaft 32. Specifically, the output end of the motor 31 and the pump shaft 32 can be connected together by a coupling, but this is not a limitation. In other alternative embodiments, the rotary drive assembly 3 may also use only the motor 31, directly driving the impeller 2 and the cooling fan 4 to rotate through the output shaft of the motor 31, or the motor 31 may drive an existing belt drive mechanism to rotate the pump shaft 32. Therefore, the structure of the rotary drive assembly 3 is not limited to these limitations.

[0022] Please continue reading. Figures 1 to 4 In one embodiment, the rotary drive assembly 3 further includes a mounting frame 33, on which the motor 31 is mounted, and the mounting frame 33 is fixedly connected to the pump head 1. Specifically, the mounting frame 33 is arranged around the motor 31 on its outer side, and the column 331 protruding in the circumferential direction of the mounting frame 33 is fixedly connected to the bottom shell 15 of the pump head 1. This fixed connection can be made by bolts, but is not limited thereto. The column 331 of the mounting frame 33 is arranged around the cooling fan 4. Within a range where the space surrounded by the column 331 of the mounting frame 33 is larger than the size of the cooling fan 4, the cooling fan 4 of this invention can be positioned between the pump head 1 and the rotary drive assembly 3.

[0023] Please see Figures 4 to 7 In one embodiment, a first airflow gap 5 is provided between the top surface of the cooling fan 4 and the bottom surface of the pump head 1, and a second airflow gap 6 is provided between the bottom surface of the cooling fan 4 and the upper part of the rotary drive assembly 3. The pump head 1, the cooling fan 4 and the rotary drive assembly 3 are respectively connected to the first airflow gap 5 and the second airflow gap 6 in the outer peripheral direction. The middle part of the cooling fan 4 is provided with a cooling air duct 41 connecting the first airflow gap 5 and the second airflow gap 6. When the rotary drive assembly 3 drives the cooling fan 4 to rotate, the airflow enters the first airflow gap 5 from the outside and flows along the outer side of the rotary drive assembly 3 in sequence through the cooling air duct 41 and the second airflow gap 6.

[0024] Preferably, the cooling fan 4 includes a fan blade housing 42, an intermediate connecting portion 43, and a fan blade body 44 connected sequentially along its radial direction. The bottom of the fan blade housing 42 is provided with a groove 421, and the middle part of the fan blade housing 42 is provided with a through hole 422 communicating with the groove 421. A first airflow gap 5 is formed between the top surface of the fan blade housing 42 and the bottom surface of the pump head 1, and a second airflow gap 6 is formed between the bottom surface of the fan blade housing 42 and the upper part of the rotary drive assembly 3. The intermediate connecting portion 43 is disposed in the groove 421 and located at a position directly opposite to the through hole 422. The fan blade body 44 is disposed in the groove 421 and inserted into the through hole 422. Several fan blade bodies 44 are respectively connected between the inner wall of the through hole 422 and the intermediate connecting portion 43 along a circumferential direction, and several cooling air ducts 41 are respectively formed between two adjacent fan blade bodies 44. Specifically, the dimensions of the fan blade body 44 along the radial direction of the cooling impeller 4 may vary. For example, the dimensions of the fan blade body 44 may gradually decrease from the end furthest from the intermediate connecting portion 43 toward the end closest to the intermediate connecting portion 43, but this is not a limitation. More specifically, the intermediate connecting portion 43 has a recessed design relative to the top surface of the fan blade housing portion 42, and the top surface of the fan blade body 44 gradually extends from the top surface of the fan blade housing portion 42 to the top surface of the intermediate connecting portion 43, but this is not a limitation.

[0025] Furthermore, the cooling fan 4 also includes an air guide 45, which is provided between each pair of adjacent fan blade bodies 44. The air guide 45 extends from the upper part of the intermediate connecting part 43 along the radial direction of the cooling fan 4 toward the bottom of the fan blade body 44. Specifically, the air guide 45 has an arc-shaped structure, but is not limited thereto.

[0026] Furthermore, the end of the fan blade body 44 connected to the through hole 422 is provided with a fan blade extension 441 that extends along the radial direction of the heat dissipation impeller 4, adhering to the bottom surface of the groove 421, and onto the inner wall of the groove 421. By providing the fan blade extension 441, when the rotary drive assembly 3 drives the heat dissipation impeller 4 to rotate, the airflow can be more fully guided and thrown onto the inner wall of the groove 421 of the fan blade housing 42, so that the heat dissipation airflow can quickly and effectively pass through the second airflow gap 6 and flow along the outer side of the rotary drive assembly 3.

[0027] like Figure 5 As shown in the diagram, arrow P represents the airflow direction when the rotary drive assembly 3 drives the cooling fan 4 to rotate. Combined with... Figures 1 to 7When the rotary drive assembly 3 drives the cooling fan 4 to rotate, the airflow enters the first airflow gap 5 from the outside, and then flows along the radial direction of the cooling fan 4 to the cooling duct 41. When the airflow passes through the cooling duct 41, under the guidance of the air guide 45, the airflow will gradually sink and flow along the radial direction of the cooling fan 4 in the groove 421 of the fan blade outer shell 42. Then, under the blocking effect of the inner wall of the groove 421, the airflow will flow out along the axial direction of the cooling fan 4, then flow through the second airflow gap 6, and finally flow along the outer side of the rotary drive assembly 3, thereby blowing air to cool the rotary drive assembly 3. At the same time, it actively intercepts and carries away the heat conducted from the pump head 1 through the drive end of the rotary drive assembly 3 in the axial direction, and dissipates it before a large amount of heat invades the rotary drive assembly 3.

[0028] In summary, the centrifugal water pump heat dissipation structure 100 of this utility model, by placing the heat dissipation fan 4 between the rotary drive assembly 3 and the pump head 1, and with the heat dissipation fan 4 sleeved on the output end of the rotary drive assembly 3, allows the rotary drive assembly 3 to drive the impeller 2 inside the pump head 1 to rotate, generating wind force through centrifugal force. This causes the heat dissipation fan 4 to blow air onto the rotary drive assembly 3 for heat dissipation. At the same time, the rotary drive assembly 3 also drives the heat dissipation fan 4 to rotate together, actively intercepting and carrying away the heat conducted axially from the pump head 1 through the drive end of the rotary drive assembly 3. This dissipates the heat before it extensively invades the rotary drive assembly 3, effectively solving the core problem of reduced heat dissipation efficiency caused by axial heat transfer in the prior art, and significantly improving the heat dissipation efficiency under the condition of the centrifugal water pump delivering hot water. Secondly, the cooling impeller 4 is directly integrated into the drive end of the rotary drive assembly 3 on the pump head 1 side. Utilizing the same shaft and rotational power source as the drive impeller 2, it completely eliminates the need for components such as retaining rings, independent fan covers, and additional fastening screws required by traditional tail-end cooling structures, effectively further reducing costs. Simultaneously, it simplifies the manufacturing and assembly process, reducing the number of steps. Furthermore, since the cooling impeller 4 is directly mounted on the drive end of the rotary drive assembly 3 on the pump head 1 side, the shape and structure of the cooling impeller 4 are essentially independent of the tail end of the motor 31. This makes the cooling solution more easily adaptable to rotary drive assemblies 3 (motor 31) of different models or origins. Only interface compatibility at the drive end of the rotary drive assembly 3 on the pump head 1 side needs to be ensured, greatly improving the design's versatility and product series scalability.

[0029] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Therefore, any equivalent variations made in accordance with the scope of the present utility model application shall still fall within the scope of the present utility model.

Claims

1. A centrifugal water pump heat dissipation structure, characterized in that, include: A pump head, wherein the pump head is provided with a accommodating space and an inlet and an outlet respectively communicating with the accommodating space; An impeller is disposed within the accommodating space; A rotary drive assembly, the output end of which passes through the accommodating space and is connected to the impeller; A cooling fan is sleeved on the output end of the rotary drive assembly, and the cooling fan is located between the pump head and the rotary drive assembly; The impeller and the cooling fan are driven to rotate by the rotary drive assembly, so that the cooling fan blows air to the rotary drive assembly to dissipate heat, while carrying away the heat conducted from the pump head toward the rotary drive assembly.

2. The centrifugal water pump heat dissipation structure according to claim 1, characterized in that, The pump head includes an upper volute and a bottom shell. The upper volute and the bottom shell are fixedly connected. The upper volute and the bottom shell enclose the receiving space. The water inlet and the water outlet are respectively disposed on the upper volute. The output end of the rotary drive assembly passes through the bottom shell and is inserted into the receiving space.

3. The centrifugal water pump heat dissipation structure according to claim 2, characterized in that, The bottom surface of the bottom shell facing the heat dissipation fan has a recessed structure that is recessed inwards from the center and the edge. The recessed structure has a number of reinforcing ribs connected between the center and the edge of the heat dissipation fan. The reinforcing ribs divide the recessed structure into a number of partition grooves.

4. The centrifugal water pump heat dissipation structure according to claim 3, characterized by The recessed structure is annular, and the reinforcing ribs are arranged at intervals along the same circumferential direction within the recessed structure.

5. The centrifugal water pump heat dissipation structure according to claim 1, characterized by The rotary drive assembly includes a motor and a pump shaft. The output end of the motor is connected to the pump shaft. The pump shaft passes through the accommodating space and is connected to the impeller. The cooling fan is sleeved on the pump shaft.

6. The centrifugal water pump heat dissipation structure according to claim 5, wherein The rotary drive assembly also includes a mounting frame, on which the motor is mounted, and the mounting frame is fixedly connected to the pump head.

7. The centrifugal water pump heat dissipation structure according to claim 1, characterized by There is a first airflow gap between the top surface of the cooling fan and the bottom surface of the pump head, and a second airflow gap between the bottom surface of the cooling fan and the upper part of the rotary drive assembly. The pump head, the cooling fan, and the rotary drive assembly are respectively connected to the first airflow gap and the second airflow gap in the outer peripheral direction. The middle part of the cooling fan is provided with a cooling air duct connecting the first airflow gap and the second airflow gap. When the rotary drive assembly drives the cooling fan to rotate, the airflow enters the first airflow gap from the outside and flows along the outer side of the rotary drive assembly in sequence through the cooling air duct and the second airflow gap.

8. The centrifugal water pump heat dissipation structure according to claim 7, characterized by The cooling fan wheel includes a fan blade outer shell, a middle connecting part, and a fan blade body connected sequentially in its radial direction. The bottom of the fan blade outer shell is provided with a groove, and the middle part of the fan blade outer shell is provided with a through hole communicating with the groove. A first airflow gap is formed between the top surface of the fan blade outer shell and the bottom surface of the pump head, and a second airflow gap is formed between the bottom surface of the fan blade outer shell and the upper part of the rotary drive assembly. The middle connecting part is disposed in the groove and located directly opposite the through hole. The fan blade body is disposed in the groove and inserted into the through hole. Several fan blade bodies are respectively connected between the inner wall of the through hole and the middle connecting part in a circumferential direction. Several cooling air ducts are respectively formed between two adjacent fan blade bodies.

9. The centrifugal water pump heat dissipation structure according to claim 8, characterized in that, The cooling fan wheel also includes an air guide section, which is provided between each of the two adjacent fan blade bodies. The air guide section extends from the upper part of the intermediate connecting part along the radial direction of the cooling fan wheel toward the bottom of the fan blade body.

10. The centrifugal water pump heat dissipation structure according to claim 8, characterized by The end of the fan blade body that connects to the through hole is provided with a fan blade extension that extends along the radial direction of the heat dissipation fan wheel, along the bottom surface of the groove, to the inner wall of the groove.

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