Cooling structure of cutting arm for heading machine
By designing a cooling structure for the cutting arm of a tunneling machine, and utilizing a storage box, built-in cold pipes, and a temperature control system, the problem of parts burning due to high temperatures in the cutting arm was solved, achieving efficient cooling and stable temperature reduction, thus improving work efficiency and cooling effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-03
- Publication Date
- 2026-03-31
AI Technical Summary
The cutting arm of the tunneling machine burned out due to high temperature during the drilling process, which affected the work efficiency.
A cooling structure including a storage box, built-in cold pipe, stirring device and temperature control system was designed. The structure achieves uniform cooling and heat preservation of the coolant through stirring, circulating cooling and temperature sensor. The structure is positioned and protected by sleeve and flange. The built-in cold pipe directly supplies coolant to the drill bit.
It effectively reduces the temperature of the cutting arm, prevents parts from burning out, improves work efficiency and coolant resource utilization, enhances the stability and protection of the built-in cooling pipe, and ensures the cooling effect of the drill bit.
Smart Images
Figure CN121761584A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cutting arm technology, specifically a cooling structure for a cutting arm used in a tunneling machine. Background Technology
[0002] A tunnel boring machine (TBM) is a machine used to excavate tunnels beneath flat ground. It mainly consists of a traveling mechanism, a working mechanism, a transport mechanism, and a transfer mechanism. As the traveling mechanism advances, the cutting head in the working mechanism continuously breaks up the rock and removes the broken rock. TBMs offer advantages such as safety, high efficiency, and good tunnel quality, but they are expensive, complex in construction, and experience significant wear and tear.
[0003] The existing telescopic cutting arm for tunneling machines is a connecting mechanism that realizes the telescopic movement of the tunneling machine's cutting head and bears the bending moment generated when the cutting head cuts. It is a comprehensive piece of equipment that performs continuous operations by mechanically breaking rocks, removing muck, and providing support.
[0004] However, in actual use, the cutting arm continuously drills through the soil, causing the drill bit to heat up significantly. This high temperature raises the temperature of the internal components, making them prone to burnout. Consequently, the cutting arm needs to be paused to cool down during excavation, reducing its excavation efficiency. Therefore, we propose a cooling structure for the cutting arm of a tunneling machine. Summary of the Invention
[0005] The purpose of this invention is to provide a cooling structure for a cutting arm of a tunneling machine to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a cooling structure for a cutting arm of a tunneling machine, comprising a storage box, a feed plate movably connected to the top of the storage box, an internal cooling pipe fixedly connected to the bottom of the storage box, and an auxiliary device disposed inside the storage box, the auxiliary device comprising:
[0007] The storage box has a mounting plate fixedly connected to its surface. A buffer strip is fixedly connected to the upper surface of the mounting plate. An electric telescopic rod is provided at the bottom axis of the right surface of the buffer box. The output end of the electric telescopic rod is fixedly connected to the discharge plate.
[0008] The motor is located on the right surface of the storage box near the front of the electric telescopic rod. The output end of the motor is fixedly connected to a rotating column. A stirring plate is fixedly connected to the outer wall of the rotating column. A temperature sensor is located at the bottom corner of the inner wall of the storage box.
[0009] Preferably, the number of stirring plates and rotating columns is two sets, and each set is symmetrically distributed on the left and right sides of the horizontal central axis of the right surface of the storage box, with the central axis of the right surface of the storage box as the axis of symmetry, thereby improving the stability of the storage box.
[0010] Preferably, a circular groove is provided at the bottom center of the inner wall of the storage box, and the cross-sectional area of the circular groove is smaller than the cross-sectional area of the discharge plate.
[0011] Preferably, the side surface of the buffer strip is provided with a guide groove so that the solution flows out to the bottom of the storage box 1 in conjunction with the mounting plate.
[0012] Preferably, the outer wall of the built-in cooling pipe is fixedly connected to a threaded cooling pipe, the input end of the threaded cooling pipe is fixedly connected to a water inlet, the input end of the water inlet is connected to a water tank, the output end of the threaded cooling pipe is fixedly connected to a water outlet, a sleeve is provided on the outer wall of the threaded cooling pipe, and a flange is provided at the vertical axis of the sleeve.
[0013] Preferably, the vertical centerline of the threaded cooling pipe coincides with the vertical centerline of the sleeve and the vertical centerline of the built-in cooling pipe, thereby improving the stability of the built-in cooling pipe.
[0014] Preferably, a heat insulation layer is provided on the inner wall of the sleeve.
[0015] Preferably, the diameter of the water inlet is adapted to the diameter of the threaded cooling pipe and the diameter of the water outlet.
[0016] Preferably, a temperature control valve is provided at the bottom of the built-in cold pipe, a temperature preset device is provided on the front surface of the temperature control valve, a drill bit is provided at the bottom of the temperature control valve, an exhaust pipe is fixedly connected to the top of the right surface of the built-in cold pipe, a one-way pressure valve is provided at the bottom of the exhaust pipe, and a compensation bag is provided at the right end of the exhaust pipe.
[0017] Preferably, the received signal of the temperature control valve is matched with the transmitted signal of the temperature presetter.
[0018] Compared with the prior art, the present invention provides a cooling structure for a cutting arm of a tunneling machine, which has the following beneficial effects:
[0019] 1. The tunneling machine uses a cooling structure for its cutting arm. When the operator needs to cool the drill bit during operation, they open the storage box and add cooling solution. The solution falls downwards due to gravity onto the upper surface of the mounting plate. When the liquid changes from a low-temperature environment to a high-temperature environment, the molecular thermal motion accelerates due to the temperature rise, increasing its evaporation rate and generating greater evaporation pressure on the liquid surface, which can easily cause splashing. The mounting plate, in conjunction with a buffer strip, protects the liquid from splashing. The solution contacts the buffer strip, reducing the impact on the bottom of the storage box. The motor is started, and the motor output shaft rotates, driving the rotating column to rotate, thereby stirring the solution in the storage box, improving the temperature uniformity of the solution and enhancing its cooling performance within the storage box.
[0020] 2. The cooling structure of the cutting arm of this tunneling machine improves the heat preservation of the device. A temperature sensor outputs the temperature value of the solution in the storage box to the external cooling equipment. After the coolant is cooled to a temperature suitable for the solution in the storage box, it flows into the threaded cooling pipe through the inlet. The threaded cooling pipe, together with the built-in cooling pipe, achieves pre-cooling treatment of the built-in cooling pipe. The inlet and outlet achieve circulating cooling of the threaded cooling pipe, improving the resource utilization rate of the device's cooling and further improving the cooling effect of the built-in cooling pipe. At the same time, the air pressure in the built-in cooling pipe decreases due to the temperature drop in the sealed container. The reduced air pressure is replenished to the compensation bladder through the exhaust pipe and the one-way pressure valve. The compensation bladder contracts due to the outflow of gas from the built-in cooling pipe, improving the protection of the built-in cooling pipe.
[0021] 3. The tunneling machine uses a cutting arm cooling structure that uses flanges to position the sleeve due to thermal expansion and contraction caused by temperature changes. The air generated when the sleeve expands insulates the internal cooling pipe, preventing rapid heat loss caused by the threaded cooling pipes cooling the internal cooling pipe, thus further promoting the cooling effect of the internal cooling pipe. At the same time, when the sleeve contracts, it works with the flange to position and protect the internal cooling pipe, improving its stability and enhancing the protection of the sleeve. When the internal cooling pipe cools down to the same temperature as the solution in the storage box, the electric telescopic rod is activated. The movement of the electric telescopic rod drives the discharge plate to move to both sides of the storage box, allowing the solution in the storage box to flow into the internal cooling pipe. At this time, the temperature in the internal cooling pipe matches the temperature of the solution, promoting the temperature stability of the internal cooling pipe in the solution.
[0022] 4. The cooling structure of the cutting arm of this tunneling machine has a temperature control valve that closes when the coolant flows into the built-in cooling pipe and the solution in the built-in cooling pipe loses heat. The solution then compensates for the temperature loss by cooling the solution in the built-in cooling pipe through the threaded cooling pipe, improving the insulation performance of the solution in the built-in cooling pipe. When the temperature of the solution in the built-in cooling pipe meets the temperature preset value, the temperature control valve opens, and the solution flows out through the outlet of the built-in cooling pipe into the drill bit, completing all the insulation measures for the solution in the built-in cooling pipe. During the process of the solution flowing out through the outlet of the built-in cooling pipe into the drill bit, the pressure in the built-in cooling pipe decreases due to the inflow of the solution, slowing down the liquid flow rate. The operator adjusts the one-way air pressure valve to allow the gas collected in the compensation bladder to flow into the built-in cooling pipe, compensating for the air pressure in the built-in cooling pipe, enhancing the flow rate of the solution in the built-in cooling pipe, and enriching the functionality of the device. Attached Figure Description
[0023] Figure 1 This is a three-dimensional schematic diagram of the macroscopic main structure of the present invention;
[0024] Figure 2 This is a cross-sectional schematic diagram of the storage box structure of the present invention;
[0025] Figure 3 This is a partial cross-sectional view of the storage box structure of the present invention;
[0026] Figure 4 This is a schematic diagram of the cross-sectional area of the built-in cold pipe in the structure of the present invention;
[0027] Figure 5 This is a schematic diagram of the mounting plate area of the present invention;
[0028] Figure 6 For the present invention Figure 2 Enlarged view of area A.
[0029] In the diagram: 1. Storage box; 101. Mounting plate; 102. Buffer strip; 103. Electric telescopic rod; 104. Motor; 105. Rotating column; 106. Stirring plate; 107. Temperature sensor; 108. Discharge plate; 2. Feeding plate; 3. Built-in cooling pipe; 30. Water tank; 31. Water inlet; 32. Threaded cooling pipe; 34. Water outlet; 35. Temperature control valve; 36. Temperature presetter; 4. Exhaust pipe; 41. One-way air pressure valve; 42. Compensation bladder; 5. Sleeve; 51. Flange; 6. Drill bit. Detailed Implementation
[0030] like Figure 1-6As shown, the present invention provides a technical solution: a cooling structure for a cutting arm of a tunneling machine, including a storage box 1, a feed plate 2 movably connected to the top of the storage box 1, an internal cooling pipe 3 fixedly connected to the bottom of the storage box 1, an auxiliary device inside the storage box 1, the auxiliary device including a mounting plate 101 fixedly connected to the surface inside the storage box 1, a buffer strip 102 fixedly connected to the upper surface of the mounting plate 101, an electric telescopic rod 103 set at the bottom axis of the right surface of the buffer box 1, a discharge plate 108 fixedly connected to the output end of the electric telescopic rod 103, a motor 104 set on the right surface of the storage box 1 near the front of the electric telescopic rod 103, a rotating column 105 fixedly connected to the output end of the motor 104, a stirring plate 106 fixedly connected to the outer wall of the rotating column 105, and a temperature sensor 107 set at the bottom corner of the inner wall of the storage box 1.
[0031] In one embodiment of the present invention, when the operator needs to cool the drill bit 6 during operation, the storage box 1 is opened, and cooling solution is added to the storage box 1. The solution falls downwards due to gravity onto the upper surface of the mounting plate 101. When the liquid changes from a low-temperature environment to a high-temperature environment, the molecular thermal motion accelerates due to the temperature rise, increasing its evaporation rate and generating significant evaporation pressure on the liquid surface, thus causing the liquid to easily splash. The mounting plate 101, in conjunction with the buffer strip 102, protects against liquid splashing. The side surface of the buffer strip 102 is provided with a guide groove, allowing the solution to flow out through the mounting plate 101 to the bottom of the storage box 1. Contact with the buffer strip 102 reduces the impact force on the bottom surface of the storage box 1. The motor 104 is started. There are two sets of stirring plates 106 and rotating columns 105. Each set is symmetrically distributed on the left and right sides of the horizontal central axis of the right surface of the storage box 1, with the central axis of the right surface of the storage box 1 as the axis of symmetry. This improves the stability of the storage box 1. The output shaft of the motor 104 rotates, driving the rotating column 105 to rotate, thereby stirring the solution in the storage box 1. This avoids the phenomenon of uneven cooling of the solution due to the accelerated movement of thermal molecules in the storage box 1, thus improving the temperature uniformity of the solution and the cooling performance of the solution in the storage box 1.
[0032] In addition, to improve the insulation of the device, a threaded cooling pipe 32 is fixedly connected to the outer wall of the built-in cooling pipe 3. The input end of the threaded cooling pipe 32 is fixedly connected to the water inlet 31, and the input pipe of the water inlet 31 is connected to the water tank 30. The output end of the threaded cooling pipe 32 is fixedly connected to the water outlet 34. A sleeve 5 is provided on the outer wall of the threaded cooling pipe 32, and a flange 51 is provided at the vertical axis of the sleeve 5. The temperature value of the solution in the storage box 1 is output to the external cooling equipment through the temperature sensor 107. After the coolant is cooled to a temperature suitable for the temperature value of the solution in the storage box 1, the coolant flows into the threaded cooling pipe 32 through the water inlet 31. The threaded cooling pipe 32, in conjunction with the built-in cooling pipe 3, realizes the cooling of the built-in cooling pipe 3. The pre-cooling treatment of the cold pipe 3 involves matching the diameter of the inlet 31 with the diameter of the threaded cooling pipe 32 and the diameter of the outlet 34. The inlet 31 and outlet 34 work together to achieve circulating cooling of the threaded cooling pipe 32, avoiding waste of residual heat after cooling and improving the resource utilization rate of the cooling device. This further enhances the cooling effect of the built-in cold pipe 3. Simultaneously, the air pressure in the built-in cold pipe 3 decreases due to the temperature drop in the sealed container. This reduced pressure air is then supplied to the compensation bladder 42 via the exhaust pipe 4 and the one-way pressure valve 41. This causes the compensation bladder 42 to contract due to the outflow of gas from the built-in cold pipe 3, preventing the built-in cold pipe 3 from... During the cooling process, contraction and deformation occur, improving the protection of the built-in cold pipe 3. The vertical centerline of the threaded cooling pipe 32 coincides with the vertical centerline of the sleeve 5 and the vertical centerline of the built-in cold pipe 3, improving the stability of the built-in cold pipe 3. The flange 51 is used to position the sleeve 5 according to the thermal expansion and contraction caused by temperature changes. A heat insulation layer is provided on the inner wall of the sleeve 5. The air generated when the sleeve 5 expands provides heat insulation for the built-in cold pipe 3, preventing rapid heat loss due to the cooling of the built-in cold pipe 3 by the threaded cooling pipe 32, further promoting the cooling effect of the built-in cold pipe 3. At the same time, the sleeve 5 contracts in conjunction with the flange 51. The built-in cold pipe 3 is positioned and protected, improving its stability and the protection of the sleeve 5. When the built-in cold pipe 3 cools down to the same temperature as the solution in the storage box 1, the electric telescopic rod 103 is activated. The electric telescopic rod 103 moves and drives the discharge plate 108 to move to both sides in the storage box 1. A circular groove is provided at the bottom axis of the inner wall of the storage box 1, and the cross-sectional area of the circular groove is smaller than that of the discharge plate 108, so that the solution in the storage box 1 flows into the built-in cold pipe 3. At this time, the temperature in the built-in cold pipe 3 is matched with the temperature of the solution, avoiding the phenomenon of heat transfer in the solution and promoting the temperature stability of the built-in cold pipe 3 in the solution.
[0033] In an embodiment of the present invention, a temperature control valve 35 is provided at the bottom of the built-in cold pipe 3, a temperature presetter 36 is provided on the front surface of the temperature control valve 35, and a drill bit 6 is provided at the bottom of the temperature control valve 35. An exhaust pipe 4 is fixedly connected to the top of the right surface of the built-in cold pipe 3, a one-way pressure valve 41 is provided at the bottom of the exhaust pipe 4, and a compensation bladder 42 is provided at the right end of the exhaust pipe 4. When the coolant flows into the built-in cold pipe 3, the temperature control valve 35 re-detects the temperature of the solution in the built-in cold pipe 3, and compares the temperature detected by the temperature control valve 35 with the temperature presetter 36. The received signal of the temperature control valve 35 matches the transmitted signal of the temperature presetter 36. When the solution temperature in the built-in cold pipe 3 experiences heat loss, the temperature control valve 35 is in a closed state, and the solution flows through the threaded cooling pipe 3. 2. Cooling compensation is performed on the solution in the built-in cold pipe 3 to improve the heat preservation of the solution in the built-in cold pipe 3. When the temperature of the solution in the built-in cold pipe 3 meets the temperature value of the temperature preset device 36, the temperature control valve 35 opens, and the solution flows out through the output port of the built-in cold pipe 3 into the drill bit 6, completing all the heat preservation measures of the solution in the built-in cold pipe 3. During the process of the solution flowing out through the output port of the built-in cold pipe 3 into the drill bit 6, the pressure in the built-in cold pipe 3 decreases due to the inflow of the solution, which slows down the liquid flow rate of the solution. The operator adjusts the one-way air pressure valve 41 to allow the gas collected in the compensation bladder 42 to flow into the built-in cold pipe 3 to perform air pressure compensation on the built-in cold pipe 3, enhance the flow rate of the solution in the built-in cold pipe 3, and enrich the functionality of the device.
[0034] In this invention, when the operator needs to cool the drill bit 6 during operation, the storage box 1 is opened, and the cooling solution is added to it. The solution falls downwards due to gravity onto the upper surface of the mounting plate 101. When the liquid changes from a low-temperature environment to a high-temperature environment, the molecular thermal motion accelerates due to the temperature rise, increasing its evaporation rate and generating significant evaporation pressure on the liquid surface, thus causing the liquid to easily splash. The mounting plate 101, in conjunction with the buffer strip 102, protects against the splashing liquid. The solution contacts the buffer strip 102, reducing the impact on the bottom surface of the storage box 1. The motor 104 is then started, and the output shaft of the motor 104 rotates, driving the rotating column 105 to rotate, thereby agitating the solution in the storage box 1. Stirring is used to prevent uneven cooling of the solution in the storage box 1 due to accelerated movement of thermal molecules. Temperature sensor 107 outputs the temperature value of the solution in the storage box 1 to an external cooling device, cooling the coolant to a temperature suitable for the solution in the storage box 1. Then, the coolant flows into the threaded cooling pipe 32 through the inlet 31. The threaded cooling pipe 32, in conjunction with the built-in cooling pipe 3, pre-cools the built-in cooling pipe 3. The inlet 31, in conjunction with the outlet 34, circulates and cools the threaded cooling pipe 32, preventing waste of residual heat after cooling. The air pressure in the built-in cooling pipe 3 decreases due to the temperature drop in the sealed container. The reduced-pressure air then passes through the exhaust pipe. 4. The one-way air pressure valve 41 replenishes the compensation bladder 42 with air, causing it to contract due to the outflow of gas from the built-in cooling pipe 3. This prevents the built-in cooling pipe 3 from shrinking and deforming during cooling. The flange 51 positions the sleeve 5 based on thermal expansion and contraction caused by temperature changes. The air generated by the expansion of the sleeve 5 insulates the built-in cooling pipe 3, preventing rapid heat loss due to the cooling effect of the threaded cooling pipe 32. This further promotes the cooling effect of the built-in cooling pipe 3. Simultaneously, the contraction of the sleeve 5, in conjunction with the flange 51, provides positioning and protection for the built-in cooling pipe 3. Once the built-in cooling pipe 3 cools to the same temperature as the solution in the storage box 1, the electric telescopic rod 103 is activated. The movement of 103 drives the discharge plate 108 to move, which moves to both sides of the storage box 1, causing the solution in the storage box 1 to flow into the built-in cooling pipe 3. At this time, the temperature in the built-in cooling pipe 3 matches the temperature of the solution, avoiding heat transfer in the solution. After the coolant flows into the built-in cooling pipe 3, the temperature control valve 35 re-detects the temperature of the solution in the built-in cooling pipe 3 and compares the temperature detected by the temperature control valve 35 with the temperature preset device 36. When there is heat loss in the solution temperature of the built-in cooling pipe 3, the temperature control valve 35 is in the closed state, and the solution compensates for the temperature loss by cooling the solution in the built-in cooling pipe 3 through the threaded cooling pipe 32. When the solution temperature in the built-in cooling pipe 3 meets the temperature value of the temperature preset device 36, the temperature control valve 35 opens.The solution flows out through the outlet of the built-in cooling pipe 3 into the drill bit 6, completing all the insulation measures for the solution within the built-in cooling pipe 3. During the flow of the solution from the outlet of the built-in cooling pipe 3 into the drill bit 6, the pressure within the built-in cooling pipe 3 decreases due to the inflow of solution, slowing down the liquid flow rate. The operator adjusts the one-way pressure valve 41 to allow the gas collected in the compensation bladder 42 to flow into the built-in cooling pipe 3, compensating for the pressure and increasing the flow rate of the solution within the built-in cooling pipe 3.
[0035] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.
Claims
1. A cooling structure for a cutting arm of a tunneling machine, comprising a storage box (1), wherein a feed plate (2) is movably connected to the top of the storage box (1), and an internal cooling pipe (3) is fixedly connected to the bottom of the storage box (1), characterized in that: The storage box (1) is equipped with an auxiliary device, which includes: Mounting plate (101), the storage box (1) has a surface fixedly connected mounting plate (101) inside, the upper surface of the mounting plate (101) is fixedly connected to a buffer strip (102), an electric telescopic rod (103) is provided at the bottom axis of the right surface of the buffer box (1), and the output end of the electric telescopic rod (103) is fixedly connected to a discharge plate (108). A motor (104) is provided on the right surface of the storage box (1) near the front of the electric telescopic rod (103). The output end of the motor (104) is fixedly connected to a rotating column (105). A stirring plate (106) is fixedly connected to the outer wall of the rotating column (105). A temperature sensor (107) is provided at the bottom corner of the inner wall of the storage box (1).
2. The cooling structure for a cutting arm of a tunneling machine according to claim 1, characterized in that: The number of stirring plates (106) and rotating columns (105) is two sets, and each set is symmetrically distributed on the left and right sides of the horizontal axis of the right surface of the storage box (1) with the central axis of the right surface of the storage box (1) as the axis of symmetry.
3. The cooling structure for a cutting arm of a tunneling machine according to claim 1, characterized in that: A circular groove is provided at the bottom axis of the inner wall of the storage box (1), and the cross-sectional area of the circular groove is smaller than the cross-sectional area of the discharge plate (108).
4. The cooling structure for a cutting arm of a tunneling machine according to claim 1, characterized in that: The buffer strip (102) has a guide groove on its side surface.
5. The cooling structure for a cutting arm of a tunneling machine according to claim 1, characterized in that: The built-in cooling pipe (3) is fixedly connected to the outer wall of the threaded cooling pipe (32), the inlet of the threaded cooling pipe (32) is fixedly connected to the water inlet (31), the inlet of the water inlet (31) is connected to the water tank (30), the outlet of the threaded cooling pipe (32) is fixedly connected to the water outlet (34), the outer wall of the threaded cooling pipe (32) is provided with a sleeve (5), and a flange (51) is provided at the vertical axis of the sleeve (5).
6. The cooling structure for a cutting arm of a tunneling machine according to claim 5, characterized in that: The vertical centerline of the threaded cooling pipe (32) coincides with the vertical centerline of the sleeve (5) and the vertical centerline of the built-in cooling pipe (3).
7. The cooling structure for a cutting arm of a tunneling machine according to claim 5, characterized in that: A heat insulation layer is provided on the inner wall of the sleeve (5).
8. The cooling structure for a cutting arm of a tunneling machine according to claim 5, characterized in that: The diameter of the inlet (31) is compatible with the diameter of the threaded cooling pipe (32) and the diameter of the outlet (34).
9. The cooling structure for a cutting arm of a tunneling machine according to claim 1, characterized in that: A temperature control valve (35) is provided at the bottom of the built-in cold pipe (3). A temperature preset device (36) is provided on the front surface of the temperature control valve (35). A drill bit (6) is provided at the bottom of the temperature control valve (35). An exhaust pipe (4) is fixedly connected to the top of the right surface of the built-in cold pipe (3). A one-way pressure valve (41) is provided at the bottom of the exhaust pipe (4). A compensation bag (42) is provided at the right end of the exhaust pipe (4).
10. The cooling structure for a cutting arm of a tunneling machine according to claim 9, characterized in that: The received signal of the temperature control valve (35) is matched with the transmitted signal of the temperature preset device (36).