A direct-axis drive device for mobile shelving

Abstract

This invention discloses a linear drive device for mobile shelving units, comprising a drive linear shaft disposed on the top of a transmission plate, a drive sprocket, and a driven sprocket disposed on the bottom of the transmission plate. A handwheel is fixedly connected to one end of the drive linear shaft. The drive sprocket is connected to the driven sprocket via a chain. The other end of the drive linear shaft passes through and is slidably connected to the drive sprocket. The drive linear shaft has two positions: a drive position and a neutral position. The drive linear shaft and the drive sprocket are equipped with a quick-connect structure and a position positioning structure. This invention features a quick-connect structure and a position positioning structure. The position positioning structure sets the drive linear shaft to two positions: drive position and neutral. In the drive position, the drive linear shaft is connected to the drive sprocket; in the neutral position, the drive linear shaft is disengaged from the drive sprocket. The quick-connect structure enables rapid switching between drive and neutral positions, making operation quick and convenient and effectively improving work efficiency.

Description

Technical Field

[0001] This invention relates to the field of mobile shelving technology, and in particular to a direct-axis drive device for mobile shelving. Background Technology

[0002] Mobile shelving units are primarily used for centralized, large-scale storage management. For such units, multiple rows of shelving units are typically arranged side-by-side, sliding along floor tracks to maximize storage space utilization. However, in existing mobile shelving systems, when multiple rows of units move simultaneously, the cranks on the driven rows rotate when one row is manually or automatically driven. This is visually unappealing, inconvenient for users, and can pose a safety hazard. To address this issue, CN106989471A discloses a mobile shelving unit's gear-engaging transmission mechanism, which describes: "In gear mode: Pushing the crank handle on the crank mounting plate causes the screw 28 to slide into the U-shaped groove on the straight shaft 02. The straight shaft 02 is fixed relative to the hollow shaft 26. The rotation of the crank handle drives the drive sprocket 03 on the hollow shaft 26 to rotate. The drive sprocket drives the large sprocket 15 via a chain, thereby driving the output sprocket 14 to rotate. The output sprocket 14 transmits power via a chain to the sprockets, shafts, and wheels in the mobile shelving unit's moving device, thus allowing the mobile shelving unit to move on the track. In neutral mode: Pulling out the crank handle on the crank mounting plate 01 causes the screw 28 to be positioned in the annular groove on the straight shaft 02, breaking the connection between the straight shaft 02 and the hollow shaft 26." In the driving mode, during the movement of the driven train, the reverse transmission power from the output sprocket 14 drives the drive sprocket 03 and the hollow shaft 26 to rotate. However, because the hollow shaft 26 is disconnected from the straight shaft 02, the straight shaft 02 does not rotate accordingly, and thus the rocker arm on the straight shaft 02 remains stationary. However, this technical solution has a drawback: when pushing the rocker arm onto the mounting plate, because the screw 28 and the U-shaped groove on the straight shaft 02 have already rotated, the screw 28 is not easy to slide into the U-shaped groove on the straight shaft 02. It is necessary to continuously rotate the straight shaft while tentatively pushing it forward, which takes a lot of time to allow the screw 28 to slide into the U-shaped groove on the straight shaft 02, thereby achieving the purpose of gear transmission. This is inconvenient to operate and has low work efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a direct-axis drive device for mobile shelving units to overcome the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A linear drive device for mobile shelving units includes a drive linear shaft mounted on the top of a transmission plate, a drive sprocket, and a driven sprocket mounted on the bottom of the transmission plate. One end of the drive linear shaft is fixedly connected to a handwheel. The drive sprocket is connected to the driven sprocket via a chain. The other end of the drive linear shaft passes through and is slidably connected to the drive sprocket. The drive linear shaft has two positions: a drive position and a neutral position. The drive linear shaft and the drive sprocket are equipped with a quick-connect structure and a position positioning structure. When the drive linear shaft is pushed inward using the handwheel and positioned to the drive position via the position positioning structure, it is connected to the drive sprocket via the quick-connect structure. When the drive linear shaft is pulled outward using the handwheel and positioned to the neutral position via the position positioning structure, it is disengaged from the drive sprocket.

[0006] Furthermore, the quick-connect structure includes a straight groove, an inclined groove, a positioning pin, and a spring. The straight groove and the inclined groove are axially formed on the inner wall of the drive sprocket, and the straight groove and the inclined groove are connected. The drive shaft has a pin hole that does not penetrate the drive shaft in the radial direction. The spring is placed in the pin hole. The positioning pin is placed on the spring and extends out of the drive shaft in the free state of the spring. The diameter of the positioning pin matches the width of the straight groove and the inclined groove.

[0007] Furthermore, the outward-facing end of the positioning post is hemispherical.

[0008] Furthermore, the gear positioning structure includes a transmission gear retaining ring and a neutral gear retaining ring. The transmission gear retaining ring and the neutral gear retaining ring are fixedly mounted on the drive shaft and are located on both sides of the drive sprocket. The drive shaft drives the transmission gear retaining ring to push inward, and the transmission gear retaining ring contacts the drive sprocket. At this time, the drive shaft is in the transmission gear position, and the axial position of the positioning post is the same as that of the straight groove. The drive shaft drives the neutral gear retaining ring to pull outward, and the neutral gear retaining ring contacts the drive sprocket. At this time, the drive shaft is in the neutral gear position, and the axial position of the positioning post is away from the axial range of the straight groove and the inclined groove.

[0009] Furthermore, the quick-connect structure includes a radial groove, seven axial grooves, and a positioning bolt. The radial groove is located at the end of the drive shaft, and the axial grooves are evenly distributed around the outer surface of the drive shaft with one end connected to the radial groove. The bottoms of the radial and axial grooves are flush. The end of the drive sprocket is provided with a positioning screw hole, and the positioning bolt is fixedly connected to the drive sprocket through the positioning screw hole. The tail of the positioning bolt passes through the drive sprocket and maintains a small distance from the bottom of the radial and axial grooves.

[0010] Furthermore, the gear positioning structure includes a first end face and a second end face. The first end face is the left end face of the radial groove, and the second end face is the right end face of the axial groove. When the drive shaft is pushed inward, the positioning bolt slides into the axial groove and contacts the second end face. At this time, the drive shaft is in the transmission gear, and the tail of the positioning bolt is located in the axial groove. When the drive shaft is pulled outward, the positioning bolt contacts the first end face. At this time, the drive shaft is in the neutral gear, and the tail of the positioning bolt is located in the radial groove.

[0011] Furthermore, a flared opening is provided at the junction of the axial groove and the radial groove.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] This invention features a quick-connect structure and a gear positioning structure. The gear positioning structure sets the drive shaft to two positions: drive gear and neutral. In the drive gear position, the drive shaft is connected to the drive sprocket; in the neutral position, the drive shaft is disengaged from the drive sprocket. This solves the problem that when multiple rows of mobile shelving units are moving simultaneously, the crank handles on the driven rows of shelving units will also rotate when one row is manually or automatically driven. The quick-connect structure enables rapid switching between drive and neutral, making operation quick and convenient and effectively improving work efficiency. Attached Figure Description

[0014] Figure 1 This is a three-dimensional outline drawing of the present invention;

[0015] Figure 2 This is the left view of the present invention;

[0016] Figure 3 This is a comparison diagram of the transmission gear and neutral gear states in Example 1;

[0017] Figure 4 This is a schematic diagram of the drive sprocket in Example 1;

[0018] Figure 5 This is a comparison diagram of the transmission gear and neutral gear states in Examples 2 and 3;

[0019] Figure 6 This is a schematic diagram of the driving linear shaft in Embodiment 2;

[0020] Figure 7 This is a schematic diagram of the driving linear shaft in Embodiment 3;

[0021] In the diagram: 1-Transmission plate, 2-Drive shaft, 201-Pin hole, 202-Radial groove, 203-Axial groove, 204-First end face, 205-Second end face, 206-Bell mouth, 3-Handwheel, 4-Drive sprocket, 401-Straight groove, 402-Slanted groove, 403-Positioning screw hole, 5-Driven sprocket, 6-Chain, 7-Positioning pin, 8-Spring, 9-Transmission stop ring, 10-Neutral stop ring, 11-Positioning bolt, 12-Bearing seat, 13-Bearing, 14-Shaft stop ring. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Example

[0023] Please see Figures 1-4 A linear drive device for mobile shelving units includes a drive linear shaft 2 mounted on the top of a transmission plate 1, a drive sprocket 4, and a driven sprocket 5 mounted on the bottom of the transmission plate 1. A bearing seat 12 is welded to the top side of the transmission plate 1, and a bearing 13 is mounted on the bearing seat 12. The shaft end of the drive sprocket 4 extends into the bearing 13 and is axially positioned on the top of the transmission plate 1 by a shaft retaining ring 14. The drive sprocket 4 is connected to the driven sprocket 5 via a chain 6. A small sprocket is coaxially fixedly mounted on the driven sprocket 5, and the small sprocket is connected to the mobile shelving unit's walking device via a chain. One end of the drive linear shaft 2 is fixedly connected to... A handwheel 3 is connected to the drive shaft 2. The other end of the drive shaft 2 passes through the drive sprocket 4 and is slidably connected to the drive sprocket 4. The drive shaft 2 has two positions: drive gear and neutral gear. The drive shaft 2 and the drive sprocket 4 are equipped with a quick-connect structure and a gear positioning structure. When the drive shaft 2 is pushed inward by the handwheel 3 and positioned to the drive gear position by the gear positioning structure, the drive shaft 2 is connected to the drive sprocket 4 through the quick-connect structure. When the drive shaft 2 is pulled outward by the handwheel 3 and positioned to the neutral gear position by the gear positioning structure, the drive shaft 2 is disengaged from the drive sprocket 4.

[0024] The quick-connect structure includes a straight groove 401, an inclined groove 402, a positioning pin 7, and a spring 8. The straight groove 401 and the inclined groove 402 are axially formed on the inner wall of the drive sprocket 4, and the straight groove 401 and the inclined groove 402 are connected. The drive shaft 2 is radially formed with a pin hole 201 that does not penetrate the drive shaft 2. The spring 8 is placed in the pin hole 201. The positioning pin 7 is placed on the spring 8 and extends out of the drive shaft 2 when the spring 8 is in a free state. The diameter of the positioning pin 7 matches the width of the straight groove 401 and the inclined groove 402, so that the positioning pin 7 can slide in the straight groove 401 and the inclined groove 402.

[0025] The end of the positioning pin 7 facing outward is hemispherical to reduce the friction between the positioning pin 7 and the inner wall of the drive sprocket 4 when the drive sprocket 4 rotates in the neutral position.

[0026] The gear positioning structure includes a transmission gear retaining ring 9 and a neutral gear retaining ring 10. The transmission gear retaining ring 9 and the neutral gear retaining ring 10 are fixedly mounted on the drive shaft 2 and are located on both sides of the drive sprocket 4. The drive shaft 2 drives the transmission gear retaining ring 9 to push inward and the transmission gear retaining ring 9 contacts the drive sprocket 4. At this time, the drive shaft 2 is in the transmission gear position, and the axial position of the positioning pin 7 is the same as that of the straight groove 401. The drive shaft 2 drives the neutral gear retaining ring 10 to pull outward and the neutral gear retaining ring 10 contacts the drive sprocket 4. At this time, the drive shaft 2 is in the neutral gear position, and the axial position of the positioning pin 7 is away from the axial range of the straight groove 401 and the inclined groove 402.

[0027] When the mobile shelving unit is stationary, there are two possible positions of the positioning post 7 and the straight groove 401. One is that the positioning post 7 is directly opposite the straight groove 401, meaning that the axis of the positioning post 7 and the axis of the straight groove 401 are on the same plane. This situation is extremely rare and is just a special case. The common situation is that the positioning post 7 and the straight groove 401 are offset, meaning that the axis of the positioning post 7 and the axis of the straight groove 401 are not on the same plane.

[0028] Transmission state: Pushing the handwheel 3 inward causes the drive shaft 2, positioning pin 7, and transmission stop ring 9 to move inward. If the positioning pin 7 is aligned with the straight groove 401, the positioning pin 7 will be pushed into the inclined groove 402 under the action of the spring 8 during its movement, and will move along the inclined groove 402 towards the straight groove 401 until the transmission stop ring 9 contacts the drive sprocket 4. This position is the transmission stop position. The end of the positioning pin 7 is stuck in the straight groove 401, realizing the transmission connection between the drive shaft 2 and the drive sprocket 4. Rotating the handwheel 3 drives the drive shaft 2 and the drive sprocket 4 to rotate simultaneously, ultimately driving the mobile shelving walking device, so that the mobile shelving can move on the track. If the positioning pin 7 is misaligned with the straight groove 401, the positioning pin 7 will continue to move along the inner wall of the drive sprocket 4 until the transmission stop ring 9 contacts the drive sprocket 4. Then, turn the handwheel 3 to drive the drive shaft 2 and the positioning pin 7 to rotate. When the positioning pin 7 rotates to the position of the straight groove 401, under the action of the spring 8, the positioning pin 7 will push into the straight groove 401, realizing the transmission connection between the drive shaft 2 and the drive sprocket 4. Continue to turn the handwheel 3 to drive the mobile shelving walking device, so that the mobile shelving can move on the track. The operation is very convenient and quick.

[0029] Neutral position: Pulling the handwheel 3 outwards causes the drive shaft 2, positioning pin 7, and neutral retaining ring 10 to move outwards. The positioning pin 7 moves along the straight groove 401 and the inclined groove 402, and moves away from the inclined groove 402, while pressing the spring 8 to move inwards towards the drive shaft 2. When the neutral retaining ring 10 contacts the drive sprocket 4, this position is the neutral position. The top of the positioning pin 7 contacts the inner wall of the drive sprocket 4, and the drive shaft 2 is disengaged from the drive sprocket 4. When the driven column next to this row of mobile shelving is moving, the reverse transmission force from the driven sprocket 5 will drive the drive sprocket 4 to rotate. Since the drive shaft 2 is disengaged from the drive sprocket 4, the drive shaft 2 will not rotate. Thus, the handwheel 3 on the drive shaft 2 is also stationary. This solves the problem that when multiple rows of mobile shelving are moving simultaneously, the crank handle on the driven column of mobile shelving will also rotate when one row of mobile shelving is manually or automatically driven. Example

[0030] Please see Figures 5-6 A linear drive device for mobile shelving units includes a drive linear shaft 2 mounted on the top of a transmission plate 1, a drive sprocket 4, and a driven sprocket 5 mounted on the bottom of the transmission plate 1. A bearing seat 12 is welded to the top side of the transmission plate 1, and a bearing 13 is mounted on the bearing seat 12. The shaft end of the drive sprocket 4 extends into the bearing 13 and is axially positioned on the top of the transmission plate 1 by a shaft retaining ring 14. The drive sprocket 4 is connected to the driven sprocket 5 via a chain 6. A small sprocket is coaxially fixedly mounted on the driven sprocket 5, and the small sprocket is connected to the mobile shelving unit's walking device via a chain. A handwheel is fixedly connected to one end of the drive linear shaft 2. 3. The other end of the drive shaft 2 passes through the drive sprocket 4 and is slidably connected to the drive sprocket 4. The drive shaft 2 is provided with two positions: drive gear and neutral gear. The drive shaft 2 and the drive sprocket 4 are provided with a quick-connect structure and a gear positioning structure. When the drive shaft 2 is pushed inward by the handwheel 3 and positioned to the drive gear position by the gear positioning structure, the drive shaft 2 is connected to the drive sprocket 4 through the quick-connect structure. When the drive shaft 2 is pulled outward by the handwheel 3 and positioned to the neutral gear position by the gear positioning structure, the drive shaft 2 is disengaged from the drive sprocket 4 through the quick-connect structure.

[0031] The quick-connect structure includes a radial groove 202, eight axial grooves 203, and a positioning bolt 11. The radial groove 202 is opened at the end of the drive shaft 2. The axial grooves 203 are evenly distributed around the outer surface of the drive shaft 2 and one end is connected to the radial groove 202. The bottom of the radial groove 202 and the axial groove 203 are flush. The end of the drive sprocket 4 is provided with a positioning screw hole 403. The positioning bolt 11 is fixedly connected to the drive sprocket 4 through the positioning screw hole 403. The tail of the positioning bolt 11 is inserted into the drive sprocket 4 and maintains a small distance from the bottom of the radial groove 202 and the axial groove 203.

[0032] The gear positioning structure includes a first end face 204 and a second end face 205. The first end face 204 is the left end face of the radial groove 202, and the second end face 205 is the right end face of the axial groove 203. When the drive shaft 2 is pushed inward, the positioning bolt 11 slides into the axial groove 203 and contacts the second end face 205. At this time, the drive shaft 2 is in the transmission gear, and the tail of the positioning bolt 11 is located in the axial groove 203. When the drive shaft 2 is pulled outward, the positioning bolt 11 contacts the first end face 204. At this time, the drive shaft 2 is in the neutral gear, and the tail of the positioning bolt 11 is located in the radial groove 202.

[0033] Transmission state: Pushing handwheel 3 inward causes the drive shaft 2 to move inward. If the positioning bolt 11 is aligned with the axial groove 203, the axial groove 203 will fit into the positioning bolt 11 and continue moving inward until the positioning bolt 11 contacts the second end face 205. This position is the transmission stop position, with the end of the positioning bolt 11 locked in the axial groove 203, achieving the transmission connection between the drive shaft 2 and the drive sprocket 4. Rotating handwheel 3 causes the drive shaft 2 and the drive sprocket 4 to rotate simultaneously, ultimately driving the mobile shelving traveling device, thus allowing the mobile shelving unit to move on the track. If the positioning bolt 11 is misaligned with the axial groove 203, the drive shaft 2 will be obstructed and unable to move inward further. In this case, simply rotate handwheel 3 slightly and push it inward tentatively to fit the axial groove 203 into the positioning bolt 11, allowing the drive shaft 2 to continue moving inward until the positioning bolt 11 contacts the second end face 205, quickly achieving the transmission connection between the drive shaft 2 and the drive sprocket 4.

[0034] Neutral position: Pull the handwheel 3 outward to disengage the positioning bolt 11 from the axial groove 203 until the positioning bolt 11 contacts the first end face 204. This position is the neutral position. The positioning bolt 11 is in the radial groove 202. The drive shaft 2 is disengaged from the drive sprocket 4. When the driven column next to this column of mobile shelving is moving, the reverse transmission force from the driven sprocket 5 will drive the drive sprocket 4 to rotate. Since the drive shaft 2 is disengaged from the drive sprocket 4, the drive shaft 2 will not rotate. Thus, the handwheel 3 on the drive shaft 2 is also stationary. This solves the problem that when multiple columns of mobile shelving are moving simultaneously, the crank handle on the driven column of mobile shelving will also rotate when one column of mobile shelving is manually or automatically driven. Example

[0035] Please see Figure 5 and Figure 7 This embodiment is basically the same as the second embodiment, except that the driving shaft 2 has four axial grooves 203, and a flared opening 206 is provided at the junction of the axial grooves 203 and the radial grooves 202. The flared opening 206 serves as a guide to facilitate the positioning bolts 11 to slide into the axial grooves 203.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A shelf direct shaft driving device, comprising a driving direct shaft (2) arranged on the top of a transmission plate (1), a driving sprocket (4) and a driven sprocket (5) arranged on the bottom of the transmission plate (1), one end of the driving direct shaft (2) is fixedly connected with a hand wheel (3), the driving sprocket (4) is in driving connection with the driven sprocket (5) through a chain (6), characterized in that: The other end of the driving straight shaft (2) passes through the driving sprocket (4) and is in sliding connection with the driving sprocket (4), the driving straight shaft (2) is provided with two positions of transmission gear and neutral gear, the driving straight shaft (2) and the driving sprocket (4) are provided with quick coupling structure and gear positioning structure, when the driving straight shaft (2) is pushed inward by the hand wheel (3) and positioned to the transmission gear position by the gear positioning structure, the driving straight shaft (2) is in transmission connection with the driving sprocket (4) through the quick coupling structure, when the driving straight shaft (2) is pulled outward by the hand wheel (3) and positioned to the neutral gear position by the gear positioning structure, the driving straight shaft (2) is disconnected from the driving sprocket (4); The quick coupling structure comprises a straight slot (401), an inclined slot (402), a positioning column (7) and a spring (8), the straight slot (401) and the inclined slot (402) are formed in the inner wall of the driving sprocket (4) in the axial direction, and the straight slot (401) is in communication with the inclined slot (402), the driving straight shaft (2) is provided with a pin hole (201) which does not penetrate the driving straight shaft (2) in the radial direction, the spring (8) is placed in the pin hole (201), the positioning column (7) is placed on the spring (8) and protrudes out of the driving straight shaft (2) in the free state of the spring (8), and the diameter of the positioning column (7) matches the width of the straight slot (401) and the inclined slot (402); The gear positioning structure comprises a transmission gear stop ring (9) and a neutral gear stop ring (10), the transmission gear stop ring (9) and the neutral gear stop ring (10) are fixedly arranged on the driving straight shaft (2) and located on the two sides of the driving sprocket (4) respectively, the driving straight shaft (2) drives the transmission gear stop ring (9) to be pushed inward, the transmission gear stop ring (9) is in contact with the driving sprocket (4), at this time, the driving straight shaft (2) is located in the transmission gear, the axial position of the positioning column (7) is the same as that of the straight slot (401), the driving straight shaft (2) drives the neutral gear stop ring (10) to be pulled outward, the neutral gear stop ring (10) is in contact with the driving sprocket (4), at this time, the driving straight shaft (2) is located in the neutral gear, and the axial position of the positioning column (7) is out of the axial range of the straight slot (401) and the inclined slot (402).

2. The direct shaft drive device for a compact shelving unit of claim 1, wherein: The end head of the outward end of the positioning column (7) is in a semispherical shape.

3. A shelf direct shaft driving device, comprising a driving direct shaft (2) arranged on the top of a transmission plate (1), a driving sprocket (4) and a driven sprocket (5) arranged on the bottom of the transmission plate (1), one end of the driving direct shaft (2) is fixedly connected with a hand wheel (3), the driving sprocket (4) is in driving connection with the driven sprocket (5) through a chain (6), characterized in that: The other end of the driving straight shaft (2) passes through the driving sprocket (4) and is in sliding connection with the driving sprocket (4), the driving straight shaft (2) is provided with two positions of transmission gear and neutral gear, the driving straight shaft (2) and the driving sprocket (4) are provided with quick coupling structure and gear positioning structure, when the driving straight shaft (2) is pushed inward by the hand wheel (3) and positioned to the transmission gear position by the gear positioning structure, the driving straight shaft (2) is in transmission connection with the driving sprocket (4) through the quick coupling structure, when the driving straight shaft (2) is pulled outward by the hand wheel (3) and positioned to the neutral gear position by the gear positioning structure, the driving straight shaft (2) is disconnected from the driving sprocket (4); The quick coupling structure comprises a radial slot (202), a plurality of axial slots (203) and a positioning bolt (11), the radial slot (202) is arranged at the end of the driving straight shaft (2), the axial slots (203) are evenly arranged on the outer surface of the driving straight shaft (2) and one end of each of the axial slots (203) is communicated with the radial slot (202), the bottom of the radial slot (202) is flush with the bottom of the axial slots (203), the end of the driving sprocket (4) is provided with a positioning screw hole (403), the positioning bolt (11) is fixedly connected with the driving sprocket (4) through the positioning screw hole (403), and the tail of the positioning bolt (11) penetrates into the driving sprocket (4) and is kept a small distance from the bottom of the radial slot (202) and the bottom of the axial slots (203). The gear positioning structure comprises a first end face (204) and a second end face (205), the first end face (204) is the left end face of the radial slot (202), the second end face (205) is the right end face of the axial slots (203), the driving straight shaft (2) is pushed inwards, the positioning bolt (11) slides into the axial slots (203) and is in contact with the second end face (205), at this time, the driving straight shaft (2) is located in the transmission gear, the tail of the positioning bolt (11) is located in the axial slots (203), the driving straight shaft (2) is pulled outwards, the positioning bolt (11) is in contact with the first end face (204), at this time, the driving straight shaft (2) is located in the idle gear, and the tail of the positioning bolt (11) is located in the radial slot (202).

4. A drive arrangement for a shelf according to claim 3, wherein: The intersection of the axial slots (203) and the radial slot (202) is provided with a bell mouth (206).

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