Filling equipment for fiber temporary plugging agent

Abstract

The invention discloses filling equipment for a fiber temporary plugging agent, and relates to the technical field of filling, the filling equipment comprises a supporting plate, pulleys are fixedly mounted at the bottom of the supporting plate, a storage tank is fixedly mounted at the top of the supporting plate, a piston type filling pump is fixedly mounted at the top of the supporting plate, and the piston type filling pump is provided with a water inlet pipe and a water outlet pipe; one-way valves are arranged in the water inlet pipe and the drainage pipe, the water inlet pipe is fixedly installed on the surface of the material storage tank, a feeding port is fixedly installed at the top of the material storage tank, a connecting pipe is fixedly installed at the top of the inner wall of the material storage tank, a motor is fixedly installed at the top of the material storage tank, and a reciprocating lead screw is fixedly installed at the output end of the motor; the precipitated fiber temporary plugging agent is stirred through rotation of the stirring plate, and if the fiber temporary plugging agent is left to stand in the storage tank for a long time, fibers can gradually settle, so that the concentration of upper-layer liquid is low, and even the phenomenon of caking occurs, uniform distribution of stirring can be kept, and precipitation and caking are prevented.

Description

Technical Field

[0001] The invention relates to the technical field of filling, in particular to a filling device for a fiber temporary plugging agent. Background Art

[0002] Fiber temporary plugging agents are usually used in oil and gas drilling, geological exploration and other fields. They are mainly used to control the fluid flow in the wellbore and temporarily block pores or cracks during the drilling process to facilitate better operations.

[0003] The patent with patent announcement number CN218077298U relates to a temporary plugging fiber adding device for reservoir transformation, which belongs to the technical field of formation injection equipment. The adding device includes an annular jet pump and a carrying liquid pump. The annular jet pump includes a working fluid channel and a sucked fluid channel, wherein the sucked fluid channel is used for temporary plugging fiber circulation; the carrying liquid pump is used to send the carrying liquid into the working fluid channel of the annular jet pump. The patent adopts an annular jet pump to achieve mixing. The temporary plugging fiber enters the annular jet pump through the sucked fluid channel and is not easy to be blocked. The carrying liquid and the temporary plugging fiber enter the annular jet pump in a flow form to achieve online mixing. The two are sprayed and mixed in the annular jet pump, and the mixing is sufficient, which can improve the dispersion of the temporary plugging fiber in the carrying liquid.

[0004] In the above patent, an annular jet pump is used to achieve mixing. The temporary blocking fiber enters the annular jet pump through the sucked fluid channel and is not easy to be blocked. The carrying liquid and the temporary blocking fiber enter the annular jet pump in a flow form to achieve online mixing. The two are sprayed and mixed in the annular jet pump. The mixing is sufficient, which can improve the dispersion of the temporary blocking fiber in the carrying liquid. However, if the fiber temporary blocking agent is left standing in the storage tank for a long time, the fiber will gradually settle, resulting in a low concentration of the upper liquid and even agglomeration, affecting the use effect. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a device for filling a fiber temporary plugging agent, which solves the problems raised in the above-mentioned background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a filling device for a fiber temporary plugging agent, comprising: a support plate, a pulley is fixedly installed at the bottom of the support plate, a storage tank is fixedly installed on the top of the support plate, a piston filling pump is fixedly installed on the top of the support plate, the piston filling pump is provided with an inlet pipe and a drain pipe, a one-way valve is arranged inside the inlet pipe and the drain pipe, the inlet pipe is fixedly installed on the surface of the storage tank, a feed port is fixedly installed on the top of the storage tank, a connecting pipe is fixedly installed on the top of the inner wall of the storage tank, a motor is fixedly installed on the top of the storage tank, a reciprocating screw is fixedly installed on the output end of the motor, a stirring plate is fixedly installed on the circumferential surface of the reciprocating screw, a rotating rod is fixedly installed on the bottom of the reciprocating screw, a sliding plate is slidably installed on the inner wall of the storage tank, a semicircular block is fixedly installed on the bottom of the sliding plate, a rotating plate is fixedly installed on the surface of the rotating rod, and the rotation of the motor drives the reciprocating screw to rotate, and the rotation of the reciprocating screw drives the stirring plate to rotate.

[0007] According to the above technical solution, a No. 1 spring is arranged between the storage tank and the sliding plate, and the sliding plate is reset by the No. 1 spring, and the rotating rod passes through the sliding plate.

[0008] According to the above technical scheme, a scraping device for scraping the inner wall of the storage tank and a mixing device for improving the mixing of the fiber temporary plugging agent are provided on the reciprocating screw. The scraping device includes a movable frame, a fixed frame, a fixed rod, a scraper and a ring. The movable frame is driven to reciprocate up and down by the rotation of the reciprocating screw. The up and down reciprocating movement of the movable frame will drive the fixed frame to reciprocate up and down. The up and down reciprocating movement of the fixed frame will drive the scraper to reciprocate up and down. The movable frame is threadedly installed on the surface of the reciprocating screw, the fixed frame is fixedly installed on the surface of the movable frame, the fixed rod is fixedly installed on the top of the inner wall of the storage tank, the scraper is fixedly installed on a side of the fixed frame away from the movable frame, the ring is fixedly installed on the bottom of the movable frame, and the fixed rod slides through the movable frame.

[0009] According to the above technical solution, a fixed plate is fixedly installed on the top of the inner wall of the storage tank, a short plate is fixedly installed on the surface of the fixed frame, a rotating block is rotatably installed on the surface of the fixed plate, and a limiting block is fixedly installed on the surface of the fixed plate. When the short plate moves upward, it will contact the rotating block, and the rotating block will be unidirectionally limited by the limiting block, so that the short plate will contact the rotating block and generate vibration during the upward movement.

[0010] According to the above technical solution, the short plate is elastic, a No. 1 torsion spring is arranged between the fixed plate and the rotating block, the No. 1 torsion spring drives the rotating block to reset, and the limit block contacts the surface of the rotating block.

[0011] According to the above technical scheme, the mixing device includes a slide, a rotating plate, a support frame, a sliding frame, a gear, a tooth plate and a stirring blade. The ring is driven downward by the downward movement of the movable frame, and the downward movement of the ring will push the slide to move downward. The downward movement of the slide will push the rotating plate to rotate, and the rotation of the rotating plate will push the sliding frame to move in the direction close to the inner wall of the storage tank. The slide is slidably mounted on the inner wall of the fixed rod, the rotating plate is rotatably mounted on the inner wall of the slide, the support frame is fixedly mounted on the inner wall of the storage tank, the sliding frame is slidably mounted on the inner wall of the support frame, the end of the rotating plate away from the slide is rotatably mounted on the surface of the sliding frame, the gear is rotatably mounted on the surface of the sliding frame, the tooth plate is fixedly mounted on the surface of the support frame, the gear is meshed with the surface of the tooth plate, and the stirring blade is fixedly mounted on the side of the gear away from the sliding frame.

[0012] According to the above technical solution, a rotating plate is rotatably installed on the inner wall of the sliding frame, a sliding seat is slidably installed on the surface of the supporting frame, the rotating plate at one end away from the sliding frame is rotatably installed on the inner wall of the sliding seat, and a square plate is fixedly installed on the surface of the sliding seat. When the sliding frame moves toward the inner wall of the storage tank, it will squeeze the rotating plate to rotate, and the rotation of the rotating plate will push the sliding seat to move downward. The downward movement of the sliding seat will drive the square plate to move downward, and the raw materials inside the storage tank will roll up and down through the up and down movement of the square plate.

[0013] According to the above technical solution, a No. 2 spring is arranged between the sliding seat and the fixed rod, and the sliding seat is reset by the No. 2 spring. A No. 3 spring is arranged between the sliding frame and the supporting frame, and the sliding frame is reset by the No. 3 spring. A No. 4 spring is arranged between the supporting frame and the sliding seat, and the sliding seat is reset by the No. 4 spring.

[0014] The present invention provides a filling device for a fiber temporary plugging agent, which has the following beneficial effects: (1) In the present invention, the reciprocating screw drives the stirring plate to rotate, and the precipitated fiber temporary plugging agent is stirred by the rotation of the stirring plate. If the fiber is left to stand in the storage tank for a long time, the fiber will gradually settle, resulting in a low concentration of the upper liquid and even agglomeration. Stirring can maintain uniform distribution, prevent precipitation and agglomeration, and ensure that the fiber can still be evenly distributed in the liquid when needed. At the same time, the upward movement of the sliding plate will push the raw materials settled on the sliding plate upward to prevent the raw materials from settling and affecting the mixing effect.

[0015] (2) The invention scrapes off the raw materials adhering to the inner wall of the storage tank through the reciprocating up and down motion of the scraper, thereby preventing the raw materials from adhering to the inner wall of the storage tank for a long time, which would cause the storage tank to be corroded and the service life to be reduced. At the same time, when the movable frame drives the fixed frame to move upward, it will drive the short plate to move upward. The upward movement of the short plate will contact the rotating block, and the rotating block will be limited by the unidirectional limit block, so that the short plate will contact the rotating block during the upward movement and generate vibration. The raw materials adhering to the scraper will be shaken off by the generated vibration, thereby improving the collection effect of the raw materials.

[0016] (3) In the present invention, the gear will contact the tooth plate when it approaches the inner wall of the storage tank, and the tooth plate will cause the gear to rotate. The rotation of the gear will drive the stirring blade to rotate. The mixing effect will be improved by the rotation of the stirring blade. At the same time, the sliding frame will move toward the inner wall of the storage tank to squeeze the rotating plate to rotate. The square plate will move up and down to make the raw materials inside the storage tank roll up and down. The up and down rolling will improve the mixing effect, make the mixing of fiber and liquid more uniform, and ensure that the fiber can be smoothly injected into the desired position. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the overall cross-sectional structure of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of the storage tank and the support plate of the present invention; Figure 4 For the present invention Figure 3 A schematic diagram of the structure enlargement of part A; Figure 5 This is a schematic diagram of the support frame and storage tank structure of the present invention; Figure 6 It is a schematic diagram of the structure of the support frame and the sliding frame of the present invention; Figure 7 It is a schematic diagram of the cross-sectional structure of the support frame of the present invention.

[0018] In the figure: 1, support plate; 2, pulley; 3, storage tank; 4, piston filling pump; 5, feed port; 6, motor; 7, connecting pipe; 8, reciprocating screw; 9, stirring plate; 10, rotating rod; 11, sliding plate; 12, semicircular block; 13, rotating plate; 141, moving frame; 142, fixed frame; 143, fixed rod; 144, scraper; 145, ring; 146, fixed plate; 147, short plate; 148, rotating block; 149, limit block; 151, sliding seat; 152, rotating plate; 153, support frame; 154, sliding frame; 155, gear; 156, toothed plate; 157, stirring blade; 158, rotating plate; 159, sliding seat; 1510, square plate. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 - Figure 7 , one embodiment of the present invention is: a filling device for a temporary fiber plugging agent, comprising: a support plate 1, a pulley 2 is fixedly installed at the bottom of the support plate 1, a storage tank 3 is fixedly installed on the top of the support plate 1, a piston filling pump 4 is fixedly installed on the top of the support plate 1, the piston filling pump 4 is provided with an inlet pipe and a drain pipe, a one-way valve is provided inside the inlet pipe and the drain pipe, the inlet pipe is fixedly installed on the surface of the storage tank 3, a feed port 5 is fixedly installed on the top of the storage tank 3, a connecting pipe 7 is fixedly installed on the top of the inner wall of the storage tank 3, a motor 6 is fixedly installed on the top of the storage tank 3, and the motor 6 A reciprocating screw 8 is fixedly installed at the output end, a stirring plate 9 is fixedly installed on the circumferential surface of the reciprocating screw 8, a rotating rod 10 is fixedly installed at the bottom of the reciprocating screw 8, a sliding plate 11 is slidably installed on the inner wall of the storage tank 3, a semicircular block 12 is fixedly installed at the bottom of the sliding plate 11, and a rotating plate 13 is fixedly installed on the surface of the rotating rod 10. The precipitated fiber temporary blocking agent is stirred by rotating the stirring plate 9. If it is left stationary in the storage tank 3 for a long time, the fibers will gradually settle, resulting in a low concentration of the upper liquid and even agglomeration. Stirring can maintain uniform distribution to prevent precipitation and agglomeration.

[0021] A spring No. 1 is arranged between the material storage tank 3 and the sliding plate 11 , and the sliding plate 11 is reset by the spring No. 1, and the rotating rod 10 passes through the sliding plate 11 .

[0022] When this embodiment is working: the raw materials inside the storage tank 3 are sucked in through the water inlet pipe by the movement of the piston of the piston filling pump 4, and then the raw materials are discharged through the drain pipe by the piston squeezing of the piston of the piston filling pump 4. At the same time, the motor 6 will be started during use, and the rotation of the motor 6 will drive the reciprocating screw 8 to rotate, and the rotation of the reciprocating screw 8 will drive the stirring plate 9 to rotate. The precipitated fiber temporary plugging agent is stirred by the rotation of the stirring plate 9. If it is left still in the storage tank 3 for a long time, the fibers will gradually settle, resulting in a low concentration of the upper liquid and even agglomeration. Stirring can maintain a uniform distribution to prevent precipitation and agglomeration, ensuring that the fibers can still be evenly distributed in the liquid when needed. At the same time, the rotation of the reciprocating screw 8 will drive the rotating rod 10 to rotate, and the rotation of the rotating rod 10 will drive the rotating plate 13 to rotate. During the rotation of the rotating plate 13, the semicircular block 12 will be pushed to move upward, and the upward movement of the semicircular block 12 will drive the sliding plate 11 to move upward. The upward movement of the sliding plate 11 will push the raw materials deposited on the sliding plate 11 upward to prevent the raw materials from settling and affecting the mixing effect.

[0023] See also Figure 1 - Figure 7 On the basis of the above embodiment, in another embodiment of the present invention, a scraping device for scraping the inner wall of the storage tank 3 and a mixing device for improving the mixing of the fiber temporary blocking agent are provided on the reciprocating screw rod 8, and the scraping device includes a movable frame 141, a fixed frame 142, a fixed rod 143, a scraper 144 and a ring 145. The movable frame 141 is threadedly mounted on the surface of the reciprocating screw rod 8, the fixed frame 142 is fixedly mounted on the surface of the movable frame 141, the fixed rod 143 is fixedly mounted on the top of the inner wall of the storage tank 3, the scraper 144 is fixedly mounted on a side of the fixed frame 142 away from the movable frame 141, the ring 145 is fixedly mounted on the bottom of the movable frame 141, and the fixed rod 143 slides through the movable frame 141 to prevent the raw material from adhering to the inner wall of the storage tank 3 for a long time, causing the storage tank 3 to be corroded and the service life to be reduced.

[0024] A fixed plate 146 is fixedly installed on the top of the inner wall of the storage tank 3, a short plate 147 is fixedly installed on the surface of the fixed frame 142, the short plate 147 is elastic, a rotating block 148 is rotatably installed on the surface of the fixed plate 146, and a limiting block 149 is fixedly installed on the surface of the fixed plate 146. The raw materials adhered to the scraper 144 are shaken off by the generated vibration, thereby improving the collection effect of the raw materials.

[0025] A torsion spring No. 1 is arranged between the fixed plate 146 and the rotating block 148 , and the rotating block 148 is driven to return to its original position by the torsion spring No. 1, and the limit block 149 is in contact with the surface of the rotating block 148 .

[0026] The mixing device includes a slide 151, a rotating plate 152, a support frame 153, a sliding frame 154, a gear 155, a tooth plate 156 and a stirring blade 157. The slide 151 is slidably mounted on the inner wall of the fixed rod 143, the rotating plate 152 is rotatably mounted on the inner wall of the slide 151, the support frame 153 is fixedly mounted on the inner wall of the storage tank 3, the sliding frame 154 is slidably mounted on the inner wall of the support frame 153, one end of the rotating plate 152 away from the slide 151 is rotatably mounted on the surface of the sliding frame 154, the gear 155 is rotatably mounted on the surface of the sliding frame 154, the tooth plate 156 is fixedly mounted on the surface of the support frame 153, the gear 155 is meshed with the surface of the tooth plate 156, and the stirring blade 157 is fixedly mounted on the side of the gear 155 away from the sliding frame 154, and the mixing effect can be improved by rotating the stirring blade 157.

[0027] A rotating plate 158 is rotatably installed on the inner wall of the sliding frame 154, and a sliding seat 159 is slidably installed on the surface of the support frame 153. The end of the rotating plate 158 away from the sliding frame 154 is rotatably installed on the inner wall of the sliding seat 159, and a square plate 1510 is fixedly installed on the surface of the sliding seat 159. The mixing effect is improved by rolling up and down, so that the mixing of the fiber and the liquid is more uniform, ensuring that the fiber can be smoothly injected into the desired position.

[0028] A No. 2 spring is arranged between the sliding seat 151 and the fixed rod 143, and the sliding seat 151 is reset by the No. 2 spring. A No. 3 spring is arranged between the sliding frame 154 and the supporting frame 153, and the sliding frame 154 is reset by the No. 3 spring. A No. 4 spring is arranged between the supporting frame 153 and the sliding seat 159, and the sliding seat 159 is reset by the No. 4 spring.

[0029] When the present embodiment is working, the reciprocating screw rod 8 rotates to drive the movable frame 141 to reciprocate up and down, and the reciprocating up and down motion of the movable frame 141 will drive the fixed frame 142 to reciprocate up and down, and the reciprocating up and down motion of the fixed frame 142 will drive the scraper 144 to reciprocate up and down, and the reciprocating up and down motion of the scraper 144 will scrape off the raw materials adhering to the inner wall of the storage tank 3, so as to prevent the raw materials from adhering to the inner wall of the storage tank 3 for a long time, causing the storage tank 3 to be corroded and the service life to be reduced. At the same time, when the movable frame 141 drives the fixed frame 142 to move upward, the short plate 147 will be driven to move upward, and the short plate 147 will contact the rotating block 148 when it moves upward, and the rotating block 148 will be unidirectionally limited by the limit block 149. The short plate 147 is elastic, and deformation is generated by the contact between the short plate 147 and the rotating block 148, so that the short plate 147 and the rotating block 148 are in contact and vibrate, and the raw materials adhering to the scraper 144 are shaken off by the generated vibration, thereby improving the collection effect of the raw materials.

[0030] The downward movement of the movable frame 141 drives the ring 145 to move downward, and the downward movement of the ring 145 drives the slide 151 to move downward, and the downward movement of the slide 151 drives the rotating plate 152 to rotate, and the rotation of the rotating plate 152 drives the sliding frame 154 to move toward the inner wall of the storage tank 3, and the sliding frame 154 moves toward the inner wall of the storage tank 3, which drives the gear 155 toward the inner wall of the storage tank 3, and the gear 155 contacts the toothed plate 156 toward the inner wall of the storage tank 3, and the toothed plate 156 causes the gear 155 to rotate. The rotation of 155 will drive the stirring blade 157 to rotate, and the rotation of the stirring blade 157 will improve the mixing effect. At the same time, the movement of the sliding frame 154 toward the inner wall of the storage tank 3 will squeeze the rotating plate 158 to rotate. The rotation of the rotating plate 158 will push the sliding seat 159 to move downward. The downward movement of the sliding seat 159 will drive the square plate 1510 to move downward. The up and down movement of the square plate 1510 will cause the raw materials inside the storage tank 3 to roll up and down. The up and down rolling will improve the mixing effect, make the mixing of the fiber and the liquid more uniform, and ensure that the fiber can be smoothly injected into the desired position.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A filling device for a fiber temporary plugging agent, characterized in that: include: A support plate (1), a pulley (2) is fixedly mounted on the bottom of the support plate (1), a storage tank (3) is fixedly mounted on the top of the support plate (1), a piston-type filling pump (4) is fixedly mounted on the top of the support plate (1), the piston-type filling pump (4) is provided with a water inlet pipe and a drain pipe, a one-way valve is provided inside the water inlet pipe and the drain pipe, the water inlet pipe is fixedly mounted on the surface of the storage tank (3), a feed port (5) is fixedly mounted on the top of the storage tank (3), a connecting pipe (7) is fixedly mounted on the top of the inner wall of the storage tank (3), and an electric A machine (6), wherein a reciprocating screw (8) is fixedly mounted on the output end of the motor (6), a stirring plate (9) is fixedly mounted on the circumferential surface of the reciprocating screw (8), a rotating rod (10) is fixedly mounted on the bottom of the reciprocating screw (8), a sliding plate (11) is slidably mounted on the inner wall of the storage tank (3), a semicircular block (12) is fixedly mounted on the bottom of the sliding plate (11), a rotating plate (13) is fixedly mounted on the surface of the rotating rod (10), and a scraping device for scraping the inner wall of the storage tank (3) and a mixing device for improving the mixing of the fiber temporary blocking agent are provided on the reciprocating screw (8).

2. The filling device of a fiber temporary plugging agent according to claim 1 is characterized in that: A No. 1 spring is provided between the material storage tank (3) and the sliding plate (11), and the rotating rod (10) passes through the sliding plate (11).

3. The filling device of a fiber temporary plugging agent according to claim 2 is characterized in that: The scraping device comprises a movable frame (141), a fixed frame (142), a fixed rod (143), a scraper (144) and a circular ring (145); the movable frame (141) is threadedly mounted on the surface of the reciprocating screw rod (8); the fixed frame (142) is fixedly mounted on the surface of the movable frame (141); the fixed rod (143) is fixedly mounted on the top of the inner wall of the material storage tank (3); the scraper (144) is fixedly mounted on a side of the fixed frame (142) away from the movable frame (141); the circular ring (145) is fixedly mounted on the bottom of the movable frame (141); and the fixed rod (143) slides through the movable frame (141).

4. The filling device of the fiber temporary plugging agent according to claim 3 is characterized in that: A fixing plate (146) is fixedly mounted on the top of the inner wall of the material storage tank (3), a short plate (147) is fixedly mounted on the surface of the fixing frame (142), a rotating block (148) is rotatably mounted on the surface of the fixing plate (146), and a limiting block (149) is fixedly mounted on the surface of the fixing plate (146).

5. The filling device of the fiber temporary plugging agent according to claim 4 is characterized in that: The short plate (147) is elastic, a first torsion spring is provided between the fixed plate (146) and the rotating block (148), and the limit block (149) is in surface contact with the rotating block (148).

6. The filling device of the fiber temporary plugging agent according to claim 5 is characterized in that: The mixing device comprises a slide (151), a rotating plate (152), a support frame (153), a sliding frame (154), a gear (155), a tooth plate (156) and a stirring blade (157); the slide (151) is slidably mounted on the inner wall of the fixed rod (143); the rotating plate (152) is rotatably mounted on the inner wall of the slide (151); the support frame (153) is fixedly mounted on the inner wall of the storage tank (3); the sliding frame (154) is slidably mounted on the inner wall of the support frame (153); one end of the rotating plate (152) away from the slide (151) is rotatably mounted on the surface of the sliding frame (154); the gear (155) is rotatably mounted on the surface of the sliding frame (154); the tooth plate (156) is fixedly mounted on the surface of the support frame (153); the gear (155) meshes with the surface of the tooth plate (156); and the stirring blade (157) is fixedly mounted on a side of the gear (155) away from the sliding frame (154).

7. The filling device of the fiber temporary plugging agent according to claim 6 is characterized in that: A rotating plate (158) is rotatably mounted on the inner wall of the sliding frame (154), a sliding seat (159) is slidably mounted on the surface of the support frame (153), one end of the rotating plate (158) away from the sliding frame (154) is rotatably mounted on the inner wall of the sliding seat (159), and a square plate (1510) is fixedly mounted on the surface of the sliding seat (159).

8. The filling device of the fiber temporary plugging agent according to claim 7, characterized in that: A No. 2 spring is provided between the sliding seat (151) and the fixed rod (143), a No. 3 spring is provided between the sliding frame (154) and the supporting frame (153), and a No. 4 spring is provided between the supporting frame (153) and the sliding seat (159).

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