Sliding error type desuperheating water flow adjusting device
Through the slip-on and erratic cooling water flow regulation device, the sliding adjustment of the slide plate and the nozzle plate solves the problem of difficult to control the steam temperature during low loads in the prior art and uneven thermal expansion of the temperature reducer, and achieves the stability of the steam temperature and the safety of the equipment.
Patent Information
- Application Number
- CN202420900856.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-28
- Publication Date
- 2025-04-15
- Estimated Expiration
- 2034-04-28
AI Technical Summary
When the temperature-reducing water regulation device of the existing steam temperature reduces the pressure of the cooled water, the atomization effect becomes worse, resulting in difficult control of the steam temperature, and the thermal expansion of the temperature reducer is uneven, which makes it easy to leak or accumulate water, causing equipment damage.
The slip-by-slip reducing water flow regulation device is adopted to slide relative to the nozzle plate through the slide plate, increase or decrease the working area of the nozzle group, adjust the flow rate, and cancel the flow rate regulation valve to ensure that the pressure of the cooled water flowing to the atomization chamber remains unchanged under variable load conditions.
It achieves the best atomization effect under variable load conditions, the steam temperature at the outlet of the temperature reducer is stable, and the temperature reducer does not leak or accumulate water, ensuring the stability of the steam temperature and the safety of the equipment.
Smart Images
Figure CN222760871U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of steam desuperheaters, in particular to a sliding type desuperheating water flow regulating device. Background Art
[0002] At present, the desuperheating water regulating device of the steam desuperheater mainly adopts the combination of desuperheating water flow regulating valve and flute nozzle. The desuperheating water flow area of the nozzle cannot be adjusted, and the flow regulating valve plays a throttling and pressure-reducing role on the desuperheating water. When the desuperheating water flow is lower than the rated value, the pressure of the desuperheating water flowing to the nozzle is reduced, the speed of the desuperheating water passing through the nozzle is reduced, and the atomization effect of the desuperheating water is deteriorated. At low load, the atomization effect of the desuperheating water deteriorates, the desuperheating water cannot be fully absorbed by the steam, the steam temperature is difficult to control, and the requirements of steam users cannot be met. At the same time, the desuperheating water that cannot be absorbed by the steam is collected at the bottom of the desuperheater, making the temperature of the upper part of the desuperheater high and the temperature of the lower part low. The uneven thermal expansion of the desuperheater causes the flange joint surface of the desuperheater to open and leak. In serious cases, the desuperheating water flows back into steam supply equipment such as steam turbines, causing serious damage to the equipment. Therefore, a new desuperheating water regulating device with simple structure, reliable operation, and timely meeting the requirements of steam users for stable steam temperature under variable load conditions is needed. Utility Model Content
[0003] In view of the problems in the prior art that when the cooling water flow rate is lower than the rated value, the throttling and pressure reducing effect of the flow regulating valve leads to a decrease in the pressure of the cooling water, a deterioration in the atomization effect, and difficulty in controlling the steam temperature, the utility model provides a sliding type cooling water flow regulating device.
[0004] The utility model provides the following technical solution: a sliding type cooling water flow regulating device, comprising:
[0005] an atomizing chamber, the atomizing chamber being connected to a cooling water inlet pipe, the atomizing chamber being provided with a nozzle plate and a slide plate sliding relative to the nozzle plate, the nozzle plate being provided with a plurality of nozzle groups along a sliding direction of the slide plate, the nozzle groups comprising a plurality of rows of atomizing nozzles, and the slide plate being provided with a plurality of water outlets along a sliding direction;
[0006] A sealing device, the sealing device comprising a pressing plate arranged on the side of the slide plate away from the nozzle plate and an elastic element arranged between the pressing plate and the side plate of the atomizing chamber, the pressing plate being provided with a water passage communicating with the water passage;
[0007] A driving device is used to drive the slide plate to slide relative to the nozzle plate.
[0008] Preferably, the nozzle plate, the slide plate and the pressure plate are all strip-shaped, the plurality of nozzle groups are arranged in sequence along the length direction of the nozzle plate, the plurality of water outlets are arranged in sequence along the length direction of the slide plate, and the water outlet covers at least one of the nozzle groups.
[0009] Preferably, the distance between two adjacent water outlets is less than or equal to the distance between two adjacent nozzle groups, and the difference between the sum of the distances between the plurality of water outlets and the sum of the distances between the plurality of nozzle groups is less than the distance between two adjacent rows of atomizing nozzles.
[0010] Preferably, the atomization chamber is connected to a buffer chamber, and the buffer chamber is provided with the cooling water inlet pipe; the driving device includes a lifting rod slidably connected to the buffer chamber and a linear electric actuator, the slide plate is connected to the transmission rod of the linear electric actuator through the lifting rod, and a seal is provided between the lifting rod and the buffer chamber.
[0011] Preferably, the lifting rod is provided with a U-shaped piece, the U-shaped piece is provided with a connecting pin, the slide plate is provided with a pin hole movably connected to the connecting pin, and the pin hole is a waist-shaped hole.
[0012] Preferably, the nozzle plate, the slide plate and the pressure plate are all annular, the plurality of nozzle groups are arranged in sequence along the circumferential direction of the nozzle plate, and the plurality of water outlets are arranged in sequence along the circumferential direction of the slide plate.
[0013] Preferably, the angle between two adjacent nozzle groups is greater than or equal to the angle between two adjacent water outlets, and the difference between the sum of the angles of multiple water outlets and the sum of the angles of multiple nozzle groups is smaller than the angle between two adjacent rows of atomizing nozzles.
[0014] Preferably, the atomization chamber is also provided with a lifting rod sleeve, and the atomization chamber is provided with the cooling water inlet pipe; the driving device includes a lifting rod slidably connected to the lifting rod sleeve and a linear electric actuator, and the lifting rod is connected to the transmission rod of the linear electric actuator; a sealing member is provided between the lifting rod and the lifting rod sleeve.
[0015] Preferably, a rack is provided at the end of the lifting rod, and the slide plate is provided with a transmission tooth meshing with the rack.
[0016] Preferably, the slide plate is provided with a driving arm, and a connecting rod is hinged between the driving arm and the lifting rod.
[0017] The beneficial effects of the utility model are as follows: the flow regulating valve is eliminated, and the flow is adjusted by increasing or decreasing the working area of the nozzle group by relative sliding of the slide plate and the nozzle plate. The cooling water flow rate is linearly related to the working area of the nozzle group, and the pressure of the cooling water flowing to the atomization chamber remains unchanged under variable load conditions, so the best atomization effect can be maintained at all times, the steam temperature at the outlet of the desuperheater is stable, and the desuperheater does not leak or accumulate water. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a schematic diagram of Example 1 of the utility model.
[0019] Figure 2 This is a schematic diagram of the nozzle plate of Example 1 of the utility model.
[0020] Figure 3 This is a schematic diagram of a skateboard according to Embodiment 1 of the present utility model.
[0021] Figure 4 This is a schematic diagram of the pressing plate of Example 1 of the utility model.
[0022] Figure 5 This is a working schematic diagram of Example 1 of the utility model.
[0023] Figure 6 This is a schematic diagram of Example 2 of the utility model.
[0024] Figure 7 This is a cross-sectional view of the atomization chamber of Example 2 of the present utility model.
[0025] Figure 8 This is a schematic diagram of the nozzle plate of Example 2 of the utility model.
[0026] Fig. 9 This is a schematic diagram of a skateboard according to Embodiment 2 of the present utility model.
[0027] Fig.10 for Fig. 9 AA cross-section diagram.
[0028] Fig.11 This is a schematic diagram of the pressure plate of Example 2 of the utility model.
[0029] Fig.12 This is a schematic diagram of Example 3 of the utility model.
[0030] : 10, cooling water inlet pipe; 20, atomizing chamber; 21, buffer chamber; 22, lifting rod sleeve; 23, inner limit ring of slide plate; 24, outer limit ring of slide plate; 25, flow plate; 30, nozzle plate; 31, nozzle group; 40, slide plate; 41, water outlet; 42, pin hole; 43, transmission gear; 44, driving arm; 50, pressure plate; 51, elastic element; 52, water passage; 53, limiter; 60, driving device; 61, lifting rod; 62, linear electric actuator; 63, U-shaped member; 64, rack; 65, connecting rod; 70, cooler pipe. DETAILED DESCRIPTION
[0031] The following is a more detailed description of the implementation of the utility model in conjunction with the drawings and the figure marks, so that those skilled in the art can implement it after reading this specification. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not used to limit the utility model. Example
[0032] The utility model provides Figure 1-4 A sliding staggered cooling water flow regulating device is shown, comprising an atomizing chamber 20 arranged in a cooler pipe 70. The atomizing chamber 20 is welded by a bottom plate, a top plate and a plurality of side plates, and the atomizing chamber 20 is in a rectangular shape. The top plate of the atomizing chamber 20 is provided with a flange, which is bolted to the cooler pipe and communicated with a buffer chamber 21 at the top of the atomizing chamber 20, and the buffer chamber 21 is provided with a cooling water inlet pipe 10. The side plate of the atomizing chamber 20 on the upstream surface is a upstream plate, and the side plate away from the upstream surface is a strip-shaped nozzle plate 30. The nozzle plate 30 is sequentially provided with three nozzle groups 31 along the length direction, and the spacing between two adjacent nozzle groups 31 is L1. The nozzle group 31 includes a plurality of rows of atomizing nozzles distributed in an array, and the spacing between two adjacent rows of atomizing nozzles is L0. The atomizing nozzles may use variable diameter holes or equal diameter holes. The length direction is Figure 1 The cooling water enters from the cooling water inlet pipe 10, flows to the atomizing chamber 20 through the buffer chamber 21, and finally is sprayed from the atomizing nozzle under a certain pressure as mist water droplets and enters the cooling device pipeline 70.
[0033] The inner side of the nozzle plate 30 is also provided with a slide plate 40 that slides relative to the nozzle plate 30. The top of the slide plate 40 extends into the buffer chamber 21 and is connected to the lifting rod 61 of the driving device 60. The slide plate 40 is also in a strip shape, and two water inlets 41 are sequentially provided along the length direction. The bottom of the nozzle plate 30 can also be regarded as a water inlet. The number of water inlets is equal to the number of nozzle groups, both of which are 3, and the distance between two adjacent water inlets 41 is L2. Please refer to Figure 3 , the distance between the upper edges of two adjacent water outlets can be defined as L2.
[0034] Driven by the driving device 60, the slide plate 40 slides relative to the nozzle plate 30 along its length direction to complete the flow regulation of the cooling water entering the cooler pipe 70. In the initial state, the slide plate 40 is at the lower limit position, its bottom limit column contacts the bottom plate of the atomizing chamber 20, and the multiple water ports 41 are staggered with the multiple nozzle groups 31, and the atomizing chamber 20 is closed. When the slide plate 40 slides upward, the multiple water ports 41 are staggered with the corresponding nozzle groups 31, and the water ports 41 are connected with some atomizing nozzles. The cooling water is sprayed from the atomizing nozzles as mist droplets and enters the cooler pipe 70. As the stroke of the slide plate 40 increases, the number of atomizing nozzles connected to the water ports 41 increases, the working area of the nozzle group increases, and the cooling water flow increases, until the multiple water ports 41 completely cover the corresponding nozzle groups 31, and the cooling water flow is increased to the maximum flow.
[0035] In this embodiment, the spacing L2 is smaller than the spacing L1, the total spacing of the three water outlets is 2L2, and the total spacing of the three nozzle groups is 2L1. The difference between the two is smaller than the spacing L0 between two adjacent rows of atomizing nozzles, so that when the slide plate 40 slides upward, the number of rows of atomizing nozzles in the three nozzle groups increases from bottom to top, and the total number of rows of atomizing nozzles in operation conforms to an arithmetic progression with a first term of 0 and a tolerance of 1, so as to improve the accuracy of flow control. For details, please refer to Figure 5, the three nozzle groups on the nozzle plate are numbered as nozzle groups 311~313 from bottom to top, and the three water outlets on the slide plate are numbered as water outlets 411~413 from bottom to top. a1~a8 are the relative states of the slide plate and the nozzle plate when the slide plate 40 rises to different heights, and the slide plate 40 rises gradually. a1 is the initial state, and multiple nozzle groups are not working. a8 is the final state, and multiple nozzle groups are in working state; in the a2 state, the water outlet 411 rises to above the first row of atomizing nozzles at the bottom of the nozzle group 311, and the first row of atomizing nozzles at the bottom of the nozzle group 311 starts to work, but the water outlets 412 and 413 are not connected to the first row of nozzles at the bottom of the nozzle groups 312 and 313; in the a3 state, the slide plate 40 rises further, and the water outlet 411 is not connected to the bottom of the nozzle group 311 The second row of atomizing nozzles, the water outlet 412 is connected to the first row of atomizing nozzles at the bottom of the nozzle group 312, and the water outlet 413 is still not connected to the first row of atomizing nozzles at the bottom of the nozzle group 313; in the a4 state, the slide plate 40 rises further, the water outlet 411 is not connected to the second row of atomizing nozzles at the bottom of the nozzle group 311, the water outlet 412 is not connected to the second row of atomizing nozzles at the bottom of the nozzle group 312, and the water outlet 413 is connected to the first row of atomizing nozzles at the bottom of the nozzle group 313; in the a5~a7 states, the slide plate 40 continues to rise, and the second row of atomizing nozzles at the bottom of the nozzle groups 311~313 start to work in turn; the slide plate 40 continues to rise, and the number of rows of working atomizing nozzles in the three nozzle groups increases from bottom to top in the above manner until it reaches the a8 state, and all the atomizing nozzles in multiple nozzle groups are in working state. The area of the water outlet 41 covers at least one of the nozzle groups 31. In this embodiment, the length of the water outlet 412 in the length direction of the slide is greater than that of the water outlet 413, so that in the a8 state, the water outlets 412 and 413 completely cover the nozzle groups 312 and 313 respectively.
[0036] In other embodiments, the spacing L2 between two adjacent water outlets may be equal to the spacing L1 between two adjacent nozzle groups, so that when the slide plate 40 slides upward, multiple nozzle groups simultaneously open the first row of atomizing nozzles at the bottom, and when the slide plate 40 continues to rise, multiple nozzle groups simultaneously open the second row of atomizing nozzles at the bottom, until all atomizing nozzles are fully opened, and the total number of rows of atomizing nozzles in operation conforms to an arithmetic progression with a first term of 0 and a tolerance of 3. The utility model does not limit the number of nozzle groups, atomizing nozzles, and water outlets, and can be determined according to actual needs.
[0037] Compared with the prior art, this regulation method eliminates the flow regulating valve and will not cause a drop in the cooling water pressure when the flow rate is small. The pressure of the cooling water flowing to the atomization chamber remains unchanged under variable load conditions, and the best atomization effect can always be maintained. The steam temperature at the outlet of the desuperheater is stable, the desuperheater does not leak or accumulate water, and the cooling water flow rate is linearly related to the working area of the nozzle group.
[0038] A sealing device is also provided in the atomizing chamber 20 to enhance the sealing performance between the slide plate 40 and the nozzle plate 30. The sealing device includes a pressing plate 50 provided on the side of the slide plate 40 away from the nozzle plate 30 and an elastic element 51 provided between the pressing plate 50 and the upstream side plate of the atomizing chamber 20. The elastic element 51 can be a compression spring, which presses the slide plate 40 toward the nozzle plate 30 by elastic force to reduce the gap. The pressing plate 50 is also in a strip shape, which plays a role of averaging pressure. The pressing plate 50 is also provided with a water passage 52 connected to the water port 41. The length of the water passage 52 in the sliding direction of the slide plate 40 is much greater than the water port 41, so that the water port 41 is always connected to the water passage 52 during the sliding process of the slide plate 40; in this embodiment, the length L3 of the water passage 52 in the sliding direction of the slide plate 40 is at least twice the length of the water port 41 toward the side of the pressing plate 50. A limiting member 53 is also provided on the top of the pressing plate 50 to limit the movable range of the pressing plate 50 , but the passage from the atomization chamber 20 to the buffer chamber 21 is not closed.
[0039] In this embodiment, the driving device 60 includes a lifting rod 61 and a linear electric actuator 62 that are slidably connected to the buffer chamber 21. A seal is provided between the lifting rod 61 and the buffer chamber 21. The seal can be a sealing filler. One end of the lifting rod 61 is connected to the transmission rod of the linear electric actuator 62 through a coupling, and the other end is provided with a U-shaped part 63. The U-shaped part 63 is provided with a connecting pin. The slide plate 40 is provided with a pin hole 42 that is movably connected to the connecting pin. The pin hole 42 is a waist-shaped hole, so that the slide plate 40 has sufficient sliding space along the axial and radial horizontal directions of the connecting pin to overcome the problem of axial non-concentricity between the slide plate 40 and the lifting rod 61 after installation. The linear electric actuator 62 drives the slide plate 40 to slide back and forth linearly along its length direction through the lifting rod 61. Example
[0040] The utility model provides Figure 6-11 A sliding staggered cooling water flow regulating device is shown. Different from Example 1, the nozzle plate 30, the slide plate 40, and the pressure plate 50 are all annular, and the atomizing chamber 20 is an annular space surrounded by the inner limiting ring 23 of the slide plate, the outer limiting ring 24 of the slide plate, the nozzle plate 30, and the flow plate 25. The nozzle plate 30 is welded to the inner limiting ring 23 of the slide plate and the outer limiting ring 24 of the slide plate, and the flow plate 25 is bolted to the inner limiting ring 23 of the slide plate and the outer limiting ring 24 of the slide plate and is provided with a sealing gasket. The outer limiting ring 24 of the slide plate is also provided with a cooling water inlet pipe 10, which is located between the pressure plate 50 and the flow plate 25. The atomizing chamber 20 is also provided with a lifting rod sleeve 22, which is connected to the inner wall of the desuperheater pipe 70 to support the atomizing chamber 20.
[0041] In order to make full use of the space of the annular plate, the nozzle plate 30 is provided with two units of nozzle groups, the two units are centrally symmetrical around the central axis of the nozzle plate, each unit is composed of three nozzle groups, and the three nozzle groups 31 are arranged in sequence along the circumferential direction of the nozzle plate 30. Please refer to the figure, the angle between two adjacent nozzle groups is α, and the angle between two adjacent rows of atomizing nozzles is γ. The water outlet of the slide plate 40 is also provided with two units of water outlets in the above manner, the two units are centrally symmetrical around the central axis of the slide plate, each unit is composed of three water outlets, and the three water outlets 41 are arranged in sequence along the circumferential direction of the slide plate 40, and the angle between two adjacent water outlets 41 is β.
[0042] In the initial state, the multiple water outlets 41 on the slide plate 40 are staggered from the multiple nozzle groups 31, and the atomization chamber is closed; when the driving device 60 drives the slide plate 40 to rotate and slide relative to the nozzle plate 30 along its circumferential direction, the water outlets 41 gradually cover the corresponding nozzle groups 31, the number of working atomizing nozzles increases, and the cooling water flow rate increases until the two are completely covered and the cooling water flow rate reaches a maximum.
[0043] In this embodiment, the angle α between two adjacent nozzle groups is greater than the angle β between two adjacent water outlets, the sum of the angles of the three nozzle groups in each unit is 2α, the sum of the angles of the three water outlets in each unit is 2β, and the difference between the two is less than the angle γ between the two columns of atomizing nozzles, so that when the slide plate 40 rotates and slides relative to the nozzle plate, the number of atomizing nozzle columns of the three nozzle groups in each unit increases successively, and the specific process is similar to that of embodiment 1, so as to improve the accuracy of flow control. In other embodiments, the angle α between two adjacent nozzle groups can be equal to the angle β between two adjacent water outlets, so that when the slide plate 40 rotates, multiple nozzle groups simultaneously open one or more columns of atomizing nozzles.
[0044] In this embodiment, the driving device 60 includes a lifting rod 61 slidably connected to the lifting rod sleeve 22 and a linear electric actuator 62. One end of the lifting rod 61 is connected to the transmission rod of the linear electric actuator 62 through a coupling, and the other end is provided with a rack 64. The edge of the slide plate 40 is provided with a transmission tooth 43 meshing with the rack 64. The linear electric actuator 62 drives the lifting rod 61 to move back and forth in a straight line along the axial direction, thereby driving the slide plate 40 to rotate back and forth. A sealing member is provided between the lifting rod 61 and the lifting rod sleeve 22, and the sealing member can be a sealing filler. Example
[0045] The utility model provides Fig.12 A sliding staggered cooling water flow regulating device is shown. Different from the embodiment 2, the slide plate 40 is provided with a driving arm 44, and a connecting rod 65 is hinged between the driving arm 44 and the lifting rod 61, and the connecting rod 65 is a fork joint.
[0046] The above are one or more embodiments of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.
Claims
1. A sliding type cooling water flow regulating device, characterized in that: include: an atomizing chamber, the atomizing chamber being connected to a cooling water inlet pipe, the atomizing chamber being provided with a nozzle plate and a slide plate sliding relative to the nozzle plate, the nozzle plate being provided with a plurality of nozzle groups along a sliding direction of the slide plate, the nozzle groups comprising a plurality of rows of atomizing nozzles, and the slide plate being provided with a plurality of water outlets along a sliding direction; A sealing device, the sealing device comprising a pressing plate arranged on the side of the slide plate away from the nozzle plate and an elastic element arranged between the pressing plate and the side plate of the atomizing chamber, the pressing plate being provided with a water passage communicating with the water passage; A driving device is used to drive the slide plate to slide relative to the nozzle plate.
2. A sliding type cooling water flow regulating device according to claim 1, characterized in that: The nozzle plate, slide plate and pressure plate are all strip-shaped, the plurality of nozzle groups are arranged in sequence along the length direction of the nozzle plate, the plurality of water outlets are arranged in sequence along the length direction of the slide plate, and the water outlet covers at least one of the nozzle groups.
3. The sliding type cooling water flow regulating device according to claim 2 is characterized in that: The distance between two adjacent water outlets is less than or equal to the distance between two adjacent nozzle groups, and the difference between the sum of the distances between the multiple water outlets and the sum of the distances between the multiple nozzle groups is less than the distance between two adjacent rows of atomizing nozzles.
4. The sliding type cooling water flow regulating device according to claim 2 is characterized in that: The atomization chamber is connected to a buffer chamber, and the buffer chamber is provided with the cooling water inlet pipe; the driving device includes a lifting rod slidably connected to the buffer chamber and a linear electric actuator, the slide plate is connected to the transmission rod of the linear electric actuator through the lifting rod, and a sealing member is provided between the lifting rod and the buffer chamber.
5. The sliding type desuperheating water flow regulating device according to claim 4 is characterized in that: The lifting rod is provided with a U-shaped piece, the U-shaped piece is provided with a connecting pin, the slide plate is provided with a pin hole movably connected to the connecting pin, and the pin hole is a waist-shaped hole.
6. The sliding type desuperheating water flow regulating device according to claim 1, characterized in that: The nozzle plate, the slide plate and the pressure plate are all annular, the plurality of nozzle groups are arranged in sequence along the circumferential direction of the nozzle plate, and the plurality of water outlets are arranged in sequence along the circumferential direction of the slide plate.
7. The sliding type desuperheating water flow regulating device according to claim 6, characterized in that: The included angle between two adjacent nozzle groups is greater than or equal to the included angle between two adjacent water outlets, and the difference between the sum of the included angles of the multiple water outlets and the sum of the included angles of the multiple nozzle groups is smaller than the included angle between two adjacent rows of atomizing nozzles.
8. The sliding type desuperheating water flow regulating device according to claim 6, characterized in that: The atomizing chamber is also provided with a lifting rod sleeve, and the atomizing chamber is provided with the cooling water inlet pipe; the driving device includes a lifting rod slidably connected to the lifting rod sleeve and a linear electric actuator, and the lifting rod is connected to the transmission rod of the linear electric actuator; a sealing member is provided between the lifting rod and the lifting rod sleeve.
9. The sliding type desuperheating water flow regulating device according to claim 8, characterized in that: The end of the lifting rod is provided with a rack, and the slide plate is provided with a transmission tooth meshed with the rack.
10. The sliding type desuperheating water flow regulating device according to claim 8, characterized in that: The slide plate is provided with a driving arm, and a connecting rod is hinged between the driving arm and the lifting rod.