A high power density DC-DC power module

Abstract

This utility model relates to the field of power module technology and proposes a high power density DC-DC power module, comprising: a device box, a base box, a first output cable, a second output cable, a second connector, and a first connector. The device box is fixedly connected to the top of the base box, and a control device is fixedly connected to the outer wall of the device box. A device power supply is fixedly connected inside the base box, a first DC boost module is fixedly connected inside the device box, and a filter is fixedly connected inside the device box. Through the filter and the second DC boost module, the AC power output by the device power supply is first converted to DC power, and then boosted by the second DC boost module to enable the device to output a specific voltage. The specific voltage can be adjusted by regulating the second boost module. The first DC boost module allows the DC power output by the device power supply to be directly boosted, giving the device two DC output systems.

Description

Technical Field

[0001] This utility model belongs to the field of power module technology, specifically relating to a high power density DC-DC power module. Background Technology

[0002] A DC-DC power module is a power converter that transforms direct current (DC) into another type of DC. By controlling the duty cycle of the switching transistors and utilizing inductors and capacitors as energy storage elements, it achieves voltage rise / fall or polarity reversal. It features high efficiency, miniaturization, and high reliability, and is widely used in mobile devices, automotive electronics, industrial automation, communication equipment, computers, and other fields to meet the power requirements of various electronic devices.

[0003] A known authorized patent with application number 202120646698.X discloses a DC-DC module power supply: It includes a PCB substrate with pre-drilled positioning holes and mounting slots. Positioning copper pins are movably mounted within the positioning holes. A single-sided aluminum substrate is fixedly mounted to the lower end of the positioning copper pins. A magnetic core is fixedly mounted on the aluminum substrate, and an inner PCB board is fixedly mounted on the magnetic core. An acrylic cover is movably mounted on the upper end of the PCB substrate, with pre-drilled fixing holes. An aluminum base is movably mounted on the lower end of the aluminum substrate, with mounting grooves for fixing the aluminum substrate. This DC-DC module power supply, through the positioning holes, allows for better connection and fixation; through the mounting slots, it allows for better heat dissipation of the magnetic core; and through the mounting grooves, it allows for easier installation of the entire device, thus improving the practicality of the module power supply.

[0004] However, in implementing the relevant technologies, the following problems were found with the above-mentioned technical solutions: Existing technologies lack circuit detection and output detection devices during output, making it difficult to guarantee the safety of the device and connected equipment during use. Therefore, a high power density DC-DC power module is proposed to solve the above problems. Utility Model Content

[0005] This invention proposes a high power density AC-DC power module, which solves the problem that existing technologies in related fields do not have circuit detection and output detection devices when outputting, making it difficult to ensure the safety of the device and connected equipment during use.

[0006] The technical solution of this utility model is as follows: a high power density AC-DC power module, comprising: a device box, a base box, a first output cable, a second output cable, a second connector and a first connector, characterized in that the device box is fixedly connected to the top of the base box, and a control device is fixedly connected to the outer wall of the device box;

[0007] The equipment power supply is fixedly connected inside the base box, the first DC boost module is fixedly connected inside the equipment box, the filter is fixedly connected inside the equipment box, and the second DC boost module is fixedly connected inside the equipment box.

[0008] A gas cylinder box is fixedly connected to the outer wall of the base box, a firing box is fixedly connected to the outer wall of the base box, normally closed temperature switches are fixedly connected to both sides of the equipment box, and a power inlet is fixedly connected to the outer wall of the base box.

[0009] Preferably, one end of the first output cable is fixedly connected to the output terminal of the device power supply, and the other end of the first output cable is fixedly connected to the input terminal of the first DC boost module;

[0010] One end of the second output cable is fixedly connected to the output end of the power input port, and the other end of the second output cable is fixedly connected to the input end of the filter. The filter and the second DC boost module are connected in series through the second output cable.

[0011] Preferably, the output terminal of the first DC boost module is fixedly connected to a second cable, the second cable passes through the equipment box, and the end of the second connector is fixedly connected to the end of the second cable;

[0012] The output terminal of the second DC boost module is fixedly connected to a first cable, which passes through the equipment box, and the first connector is fixedly connected to the end of the first cable.

[0013] Two storage sleeves are fixedly connected to both sides of the bottom box.

[0014] Preferably, two voltage detection devices are fixedly connected to the outer wall of the equipment box. The voltage detection devices are electrically connected to the control device. The control device includes a main unit, a display screen is fixedly connected to the outer wall of the main unit, and two selection buttons are fixedly connected to the outer wall of the main unit. The control device is electrically connected to a first output cable and a second output cable. An emergency stop button is fixedly connected to the outer wall of the equipment box, and the emergency stop button controls the output terminal of the equipment power supply.

[0015] Preferably, the top of the equipment box is provided with a ventilation window, a motor is fixedly connected inside the equipment box, and a ventilation fan is fixedly connected to the output end of the motor.

[0016] Preferably, a power supply for the equipment is fixedly connected inside the base box, and the output terminal of the power supply inlet is connected to the input terminal of the power supply for the equipment.

[0017] Preferably, the gas cylinder box is the same as the base box, the gas cylinder box includes an outer box, the inner wall of the outer box is fixedly connected to a supporting bottom, the upper wall of the supporting bottom is fixedly connected to a gas cylinder, and the inner wall of the outer box is fixedly connected to a partition.

[0018] Preferably, the firing box includes a component box, a fixed plate is fixedly connected to the inner wall of the component box, a sliding plate is slidably connected to the outer wall of the fixed plate, a rack is provided on the outer wall of the sliding plate, a servo motor is fixedly connected to the inside of the component box, a gear is fixedly connected to the output end of the servo motor, the gear meshes with the rack provided on the outer wall of the sliding plate, a limit rod is fixedly connected to the inside of the component box, the other end of the limit rod is fixedly connected to the outer wall of a partition, a moving plate is slidably connected to the outer wall of the limit rod, a spring is fixedly connected to the inner wall of the component box, the end of the spring is fixedly connected to one side of the moving plate, the other side of the moving plate is slidably connected to the outer wall of the sliding plate, the size of the moving plate is smaller than the size of the notch in the fixed plate, a firing pin is fixedly connected to the outer wall of the moving plate, the partition has a through hole, the firing pin is located inside the through hole in the partition, the position of the firing pin corresponds to the pre-rupture point of the gas cylinder, and a backup power supply is fixedly connected to the inner wall of the component box.

[0019] Preferably, normally closed temperature switches are fixedly connected to both sides of the equipment box. The first cable is connected to the input terminal of the normally closed temperature switch and then exits from the output terminal. The second cable is connected to the input terminal of the normally closed temperature switch and then exits from the output terminal. A bracket is fixedly connected to the outer wall of the equipment box, and the other end of the bracket is sleeved on the outer wall of the second cable and the first cable.

[0020] Preferably, the lower surface of the base box is fixedly connected to multiple traveling wheels, and the lower surface of the base box is fixedly connected to multiple hydraulic lifting rods.

[0021] The working principle and beneficial effects of this utility model are as follows:

[0022] By using a filter and a second DC boost module, the AC power output from the device's power supply is first converted to DC power. Then, the DC voltage is boosted by the second DC boost module. By adjusting the second boost module, a specific output voltage can be achieved. By using the first DC boost module, the DC power output from the device is directly boosted, giving the device two DC output systems. This prevents the device from becoming unusable for a short period due to the failure of a single output system. In conjunction with the control device, it can operate individual circuits. In conjunction with the voltage detection device, it can detect changes and fluctuations in the output voltage of each line during operation. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0025] Figure 2 This is a rear-view three-dimensional structural diagram of the present invention;

[0026] Figure 3 This is a rear cross-sectional three-dimensional structural diagram of the present invention;

[0027] Figure 4 This is a cross-sectional three-dimensional structural diagram of the gas cylinder box of this utility model;

[0028] Figure 5 This utility model Figure 4 A magnified structural diagram at point A.

[0029] In the diagram: 1. Equipment box; 2. Base box; 3. Equipment power supply; 4. First output cable; 5. Second output cable; 6. First DC boost module; 7. Filter; 8. Second DC boost module; 9. Control device; 901. Main unit; 902. Display screen; 903. Selection button; 10. Emergency stop button; 11. Voltage detection device; 12. Second connector; 13. Ventilation window; 14. Motor; 15. Ventilation fan; 16. Storage sleeve; 17. Power inlet. ; 18. Walking wheel; 19. Second cable; 20. First cable; 21. First connector; 22. Gas cylinder box; 221. Outer box; 222. Gas cylinder; 223. Support base; 224. Partition; 23. Firing box; 231. Equipment box; 232. Backup power supply; 233. Servo motor; 234. Spring; 235. Motion plate; 236. Gear; 237. Sliding plate; 238. Fixing plate; 289. Firing pin; 25. Normally closed temperature switch; 26. Bracket. Detailed Implementation

[0030] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model.

[0031] Example 1

[0032] Please see Figure 1-5, a high power density DC-DC power module, comprising: a device box 1, a base box 2, a first output cable 4, a second output cable 5, a second connector 12 and a first connector 21, characterized in that the device box 1 is fixedly connected to the top of the base box 2, and a control device 9 is fixedly connected to the outer wall of the device box 1;

[0033] The bottom box 2 is fixedly connected to the equipment power supply 3, the equipment box 1 is fixedly connected to the first DC boost module 6, the equipment box 1 is fixedly connected to the filter 7, and the equipment box 1 is fixedly connected to the second DC boost module 8.

[0034] A gas cylinder box 22 is fixedly connected to the outer wall of the bottom box 2, a firing box 23 is fixedly connected to the outer wall of the bottom box 2, normally closed temperature switches 25 are fixedly connected to both sides of the equipment box 1, and a power inlet 17 is fixedly connected to the outer wall of the bottom box 2.

[0035] The technical solution provided in this embodiment is as follows: First, push the device into the work location. Start the lifting hydraulic rod 24 to raise the device, lifting the traveling wheels 18 off the ground to prevent accidental movement during testing. Then, start the motor 14 to drive the ventilation fan 15 to rotate, cooling the components inside the equipment box 1. First, insert the second connector 12 into the connection point. Then, press the selection button 903 near the second connector 12. The current output from the power input 17 is then transmitted to the first DC boost module 6 via the first output cable 4 to boost the voltage. Afterward, the current is transmitted to the receiving device via the second connector 12. If the other side is selected for electrical output, first insert the first connector 21 into the connection point and press the selection button near the first connector 21. Then, the power input 17 outputs current via the second output cable 5. The current first passes through the filter 7 to convert AC to DC. The current is boosted by the second DC boost module 8, and then input to the first connector 21 through the first cable 20 and input to the receiving device. During output, the voltage detection device 11 detects the real-time voltage of each channel and displays it on the display screen 902. The host 901 judges whether the device is operating normally. In case of unexpected power failure or emergency power use, the first output cable is connected to the device power supply 3, and the device power supply 3 provides temporary power. The voltage detection device 11 and the control device 9 simultaneously detect the circuit and determine whether there is any abnormality. When the device has an abnormal condition, such as overheating, the normally closed contact of the normally closed temperature switch 25 is opened, physically disconnecting the power output of the device, and the emergency stop button 10 is pressed immediately to disconnect the power supply of the device to prevent other components of the device from malfunctioning. When the power of the device power supply 3 is insufficient, it can be charged through the power input port 17.

[0036] Example 2

[0037] Based on Embodiment 1, in this embodiment: the firing box 23 includes a component box 231. A fixing plate 238 is fixedly connected to the inner wall of the component box 231. A sliding plate 237 is slidably connected to the outer wall of the fixing plate 238. A rack is provided on the outer wall of the sliding plate 237. A servo motor 233 is fixedly connected inside the component box 231. A gear 236 is fixedly connected to the output end of the servo motor 233. The gear 236 meshes with the rack provided on the outer wall of the sliding plate 237. A limit rod 230 is fixedly connected inside the component box 231. The other end of the limit rod 230 is fixedly connected to the outer wall of the partition 224. A moving plate 235 is slidably connected to the outer wall of component box 231. A spring 234 is fixedly connected to the inner wall of component box 231. The end of spring 234 is fixedly connected to one side of moving plate 235. The other side of moving plate 235 is slidably connected to the outer wall of sliding plate 237. The size of moving plate 235 is smaller than the size of the notch in fixed plate 238. A firing pin 239 is fixedly connected to the outer wall of moving plate 235. A through hole is opened in partition 224. The firing pin 239 is located inside the through hole opened in partition 224. The position of firing pin 239 corresponds to the pre-opening of gas cylinder 222. A backup power supply 232 is fixedly connected to the inner wall of component box 231.

[0038] The technical solution provided in this embodiment is as follows: When the device experiences excessively high temperature or flames, the servo motor 233 is activated. The activation of the servo motor 233 drives the gear 236 to rotate, causing the sliding plate 237 to move downward. The moving plate 235 is fixed by the limiting rod 230, so that the moving plate 235 will not be displaced when the sliding plate 237 moves. After the sliding plate 237 completely releases the restriction on the moving plate 235, the moving plate 235 is pushed forward rapidly under the action of the spring 234, causing the firing pin 239 to strike the gas cylinder 222, which rapidly releases the carbon dioxide gas inside the gas cylinder 222, quickly cooling the inside of the device and temporarily isolating oxygen, thus buying time for subsequent processing.

[0039] Furthermore, one end of the first output cable 4 is fixedly connected to the output end of the device power supply 3, and the other end of the first output cable 4 is fixedly connected to the input end of the first DC boost module 6.

[0040] One end of the second output cable 5 is fixedly connected to the output end of the power input port 17, and the other end of the second output cable 5 is fixedly connected to the input end of the filter 7. The filter 7 and the second DC boost module 8 are connected in series through the second output cable 5.

[0041] Specifically, by setting the first DC boost module 6, the device can boost the DC power output from the equipment power supply 3, so that the device can directly output power through the equipment power supply 3 in case of emergency power use such as power outage.

[0042] Furthermore, the output end of the first DC boost module 6 is fixedly connected to the second cable 19, the second cable 19 passes through the equipment box 1, and the end of the second connector 12 is fixedly connected to the end of the second cable 19;

[0043] The output end of the second DC boost module 8 is fixedly connected to the first cable 20, which passes through the equipment box 1, and the first connector 21 is fixedly connected to the end of the first cable 20.

[0044] Two storage sleeves 16 are fixedly connected to both sides of the bottom box 2.

[0045] Specifically, the setup of two different charging guns allows the device to detect different charging ports, giving it greater compatibility.

[0046] Furthermore, two voltage detection devices 11 are fixedly connected to the outer wall of the equipment box 1. The voltage detection devices 11 are electrically connected to the control device 9. The control device 9 includes a host 901. A display screen 902 is fixedly connected to the outer wall of the host 901. Two selection buttons 903 are fixedly connected to the outer wall of the host 901. The control device 9 is electrically connected to the first output cable 4 and the second output cable 5. An emergency stop button 10 is fixedly connected to the outer wall of the equipment box 1. The emergency stop button 10 controls the output terminal of the equipment power supply 3.

[0047] Specifically, the emergency stop button 10 is designed to prevent the device from cutting off the power supply 3 in a timely manner in case of sudden abnormalities, thus avoiding more serious situations.

[0048] Furthermore, a ventilation window 13 is provided at the top of the equipment box 1, and a motor 14 is fixedly connected inside the equipment box 1. A ventilation fan 15 is fixedly connected to the output end of the motor 14.

[0049] Specifically, the ventilation window 13 and the ventilation fan 15 can promptly remove the heat emitted by the internal components of the device during operation, thus preventing damage caused by heat buildup inside the device.

[0050] Furthermore, the equipment power supply 3 is fixedly connected inside the bottom box 2, and the output terminal of the power input port 17 is connected to the input terminal of the equipment power supply 3.

[0051] Specifically, the power input 17 is designed to allow the device to be charged quickly and easily when not in use, effectively increasing the device's usage time.

[0052] Furthermore, the gas cylinder box 22 is the same as the bottom box 2. The gas cylinder box 22 includes an outer box 221. The inner wall of the outer box 221 is fixedly connected to a supporting bottom 223. The upper wall of the supporting bottom 223 is fixedly connected to a gas cylinder 222. The inner wall of the outer box 221 is fixedly connected to a partition 224.

[0053] Specifically, the partition 224 is designed to prevent the gas cylinder 222 from being accidentally activated by other components during use.

[0054] Furthermore, the firing box 23 includes a component box 231. A fixing plate 238 is fixedly connected to the inner wall of the component box 231, and a sliding plate 237 is slidably connected to the outer wall of the fixing plate 238. A rack is provided on the outer wall of the sliding plate 237. A servo motor 233 is fixedly connected inside the component box 231. A gear 236 is fixedly connected to the output end of the servo motor 233. The gear 236 meshes with the rack provided on the outer wall of the sliding plate 237. A limit rod 230 is fixedly connected inside the component box 231. The other end of the limit rod 230 is fixedly connected to the outer wall of the partition 224. The outer wall of the limit rod 230 slides... A moving plate 235 is connected to the component box 231. A spring 234 is fixedly connected to the inner wall of the component box 231. The end of the spring 234 is fixedly connected to one side of the moving plate 235. The other side of the moving plate 235 is slidably connected to the outer wall of the sliding plate 237. The size of the moving plate 235 is smaller than the size of the notch in the fixed plate 238. A firing pin 239 is fixedly connected to the outer wall of the moving plate 235. A through hole is opened in the partition 224. The firing pin 239 is located inside the through hole opened in the partition 224. The position of the firing pin 239 corresponds to the pre-rupture point of the gas cylinder 222. A backup power supply 232 is fixedly connected to the inner wall of the component box 231.

[0055] Specifically, the firing pin 239 and the spring 234 are configured so that when the moving plate 235 moves, the firing pin 239 can pass through the partition 224 correctly and then break the gas cylinder 222, so that the gas cylinder 222 can quickly output carbon dioxide gas.

[0056] Furthermore, normally closed temperature switches 25 are fixedly connected to both sides of the equipment box 1. The first cable 20 is connected to the input end of the normally closed temperature switch 25 and then exits from the output end. The second cable 19 is connected to the input end of the normally closed temperature switch 25 and then exits from the output end. A bracket 26 is fixedly connected to the outer wall of the equipment box 1. The other end of the bracket 26 is sleeved on the outer wall of the second cable 19 and the first cable 20.

[0057] Specifically, the normally closed temperature switch 25 is designed to quickly cut off the cable when it overheats, preventing the cable from continuing to output current when overheated, which could damage the vehicle or equipment.

[0058] Furthermore, multiple traveling wheels 18 are fixedly connected to the lower surface of the base box 2, and multiple hydraulic lifting rods 24 are fixedly connected to the lower surface of the base box 2.

[0059] Specifically, the hydraulic lifting rod 24 is designed to lift the traveling wheels 18 off the ground when the device is in operation, thus preventing the device from moving accidentally during operation.

[0060] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A high power density DC-DC power supply module, comprising: The equipment box (1), the base box (2), the first output cable (4), the second output cable (5), the second connector (12) and the first connector (21) are characterized in that the equipment box (1) is fixedly connected to the top of the base box (2), and a control device (9) is fixedly connected to the outer wall of the equipment box (1); The bottom box (2) is fixedly connected to the equipment power supply (3), the equipment box (1) is fixedly connected to the first DC boost module (6), the equipment box (1) is fixedly connected to the filter (7), and the equipment box (1) is fixedly connected to the second DC boost module (8). A gas cylinder box (22) is fixedly connected to the outer wall of the bottom box (2), a firing box (23) is fixedly connected to the outer wall of the bottom box (2), normally closed temperature switches (25) are fixedly connected to both sides of the equipment box (1), and a power inlet (17) is fixedly connected to the outer wall of the bottom box (2).

2. The high power density DC-DC power supply module according to claim 1, characterized in that: One end of the first output cable (4) is fixedly connected to the output end of the device power supply (3), and the other end of the first output cable (4) is fixedly connected to the input end of the first DC boost module (6); One end of the second output cable (5) is fixedly connected to the output end of the power input port (17), and the other end of the second output cable (5) is fixedly connected to the input end of the filter (7). The filter (7) and the second DC boost module (8) are connected in series through the second output cable (5).

3. The high power density DC-DC power supply module according to claim 1, characterized in that: The output end of the first DC boost module (6) is fixedly connected to a second cable (19), the second cable (19) passes through the equipment box (1), and the end of the second connector (12) is fixedly connected to the end of the second cable (19); The output end of the second DC boost module (8) is fixedly connected to a first cable (20), the first cable (20) passes through the equipment box (1), and the first connector (21) is fixedly connected to the end of the first cable (20); Two storage sleeves (16) are fixedly connected to both sides of the bottom box (2).

4. A high power density DC-DC power supply module according to claim 1, characterized in that: Two voltage detection devices (11) are fixedly connected to the outer wall of the equipment box (1). The voltage detection devices (11) are electrically connected to the control device (9). The control device (9) includes a host (901). A display screen (902) is fixedly connected to the outer wall of the host (901). Two selection buttons (903) are fixedly connected to the outer wall of the host (901). The control device (9) is electrically connected to the first output cable (4) and the second output cable (5). An emergency stop button (10) is fixedly connected to the outer wall of the equipment box (1). The emergency stop button (10) controls the output terminal of the equipment power supply (3).

5. A high power density DC-DC power supply module according to claim 1, characterized in that: The top of the equipment box (1) is provided with a ventilation window (13), and a motor (14) is fixedly connected inside the equipment box (1). A ventilation fan (15) is fixedly connected to the output end of the motor (14).

6. A high power density DC-DC power supply module according to claim 1, characterized in that: The bottom box (2) is fixedly connected to the equipment power supply (3), and the output end of the power input port (17) is connected to the input end of the equipment power supply (3).

7. A high power density DC-DC power supply module according to claim 1, characterized in that: The gas cylinder box (22) is the same as the bottom box (2). The gas cylinder box (22) includes an outer box (221). The inner wall of the outer box (221) is fixedly connected to a supporting bottom (223). The upper wall of the supporting bottom (223) is fixedly connected to a gas cylinder (222). The inner wall of the outer box (221) is fixedly connected to a partition (224).

8. A high power density DC-DC power supply module according to claim 1, characterized in that: The firing box (23) includes a component box (231). A fixing plate (238) is fixedly connected to the inner wall of the component box (231). A sliding plate (237) is slidably connected to the outer wall of the fixing plate (238). A rack is provided on the outer wall of the sliding plate (237). A servo motor (233) is fixedly connected inside the component box (231). A gear (236) is fixedly connected to the output end of the servo motor (233). The gear (236) meshes with the rack provided on the outer wall of the sliding plate (237). A limit rod (230) is fixedly connected inside the component box (231). The other end of the limit rod (230) is fixedly connected to the outer wall of the partition (224). The outer wall of the limit rod (230) is slidably connected to the outer wall of the partition (224). A moving plate (235) is connected to the inner wall of the component box (231), and a spring (234) is fixedly connected to the inner wall of the component box (231). The end of the spring (234) is fixedly connected to one side of the moving plate (235), and the other side of the moving plate (235) is slidably connected to the outer wall of the sliding plate (237). The size of the moving plate (235) is smaller than the size of the notch in the fixed plate (238). A firing pin (239) is fixedly connected to the outer wall of the moving plate (235). A through hole is opened in the partition plate (224), and the firing pin (239) is located inside the through hole opened in the partition plate (224). The position of the firing pin (239) corresponds to the pre-rupture point of the gas cylinder (222). A backup power supply (232) is fixedly connected to the inner wall of the component box (231).

9. A high power density DC-DC power supply module according to claim 3, characterized in that: Normally closed temperature switches (25) are fixedly connected to both sides of the equipment box (1). The first cable (20) is connected to the input end of the normally closed temperature switch (25) and then exits from the output end. The second cable (19) is connected to the input end of the normally closed temperature switch (25) and then exits from the output end. A bracket (26) is fixedly connected to the outer wall of the equipment box (1). The other end of the bracket (26) is sleeved on the outer wall of the second cable (19) and the first cable (20).

10. A high power density DC-DC power supply module according to claim 1, characterized in that: The lower surface of the base box (2) is fixedly connected with multiple walking wheels (18), and the lower surface of the base box (2) is fixedly connected with multiple hydraulic lifting rods (24).

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