Fabric bone position positioning structure and fabric bone position positioning method

Abstract

The invention relates to the technical field of sewing, in particular to a fabric bone position positioning structure and a fabric bone position positioning method. The fabric bone position positioning structure comprises a driving assembly, a driving wheel and a detection piece, and the driving wheel is connected to the output end of the driving assembly and used for being matched with the roller to clamp the fabric so that the driving assembly can drive the driving wheel to rotate and drive the fabric to rotate synchronously. Wherein the detection piece is connected to the driving assembly, and the detection piece is used for detecting a speed signal of the output end of the driving assembly. According to the fabric bone position positioning structure and the fabric bone position positioning method provided by the invention, the problem that an existing sewing machine cannot normally complete bone position searching when encountering a high bone position is solved.

Description

Technical Field

[0001] The present application relates to the field of sewing technology, and in particular to a fabric bone positioning structure and a fabric bone positioning method. Background Art

[0002] Currently, sewing machines require the positioning of the fabric's joints during the sewing process, ensuring that the seam start position on the fabric maintains a certain distance from the joint to meet sewing requirements. Typically, sewing machines have an automatic joint-finding device. This device uses a stepper motor to drive a roller, which, through the cooperation of the roller and drum, drives the fabric to rotate. After the joint detection sensor detects the joint through an infrared light path, the roller is set to rotate to a specified angle and then stop, thereby positioning the joint on the fabric at the specified position.

[0003] To improve the efficiency of bone location search, stepper motors typically drive the rollers at higher speeds. However, because the faster the stepper motor, the smaller the output torque. This results in higher bone locations on the fabric creating significant resistance on the rollers, causing them to stop. This resistance, when transmitted to the stepper motor, causes the stepper motor to lose steps. Furthermore, the controller cannot detect when the stepper motor has lost steps and will continue to output high-speed rotation signals. This causes the stepper motor to remain out of step, causing the rollers to remain stopped, and thus preventing the bone location search from being completed properly. Summary of the Invention

[0004] Based on this, it is necessary to provide a fabric bone position positioning structure and a fabric bone position positioning method to solve the problem that the existing sewing machine cannot normally complete the bone position search when encountering a high bone position.

[0005] The present application provides a fabric bone position positioning structure, which includes a drive assembly, a drive wheel and a detection member, wherein the drive wheel is connected to the output end of the drive assembly and is used to cooperate with a roller to clamp the fabric, so that the drive assembly can drive the drive wheel to rotate and drive the fabric to rotate synchronously; wherein the detection member is connected to the drive assembly, and the detection member is used to detect the speed signal of the output end of the drive assembly.

[0006] In one embodiment, a detection rack is provided on the driving wheel, and the detection rack rotates synchronously with the driving wheel; wherein the detection member is configured as a sensor, and the sensor cooperates with the detection rack inductively.

[0007] In one embodiment, there are multiple detection racks, and the multiple detection racks are evenly spaced along the circumference of the driving wheel.

[0008] In one embodiment, the driving wheel includes a wheel body, a detection disk and a first rotating shaft, the wheel body and the detection disk are both mounted on and connected to the first rotating shaft, and the first rotating shaft is connected to the output end of the driving assembly; wherein, a plurality of the detection racks are arranged on the detection disk.

[0009] In one embodiment, the driving assembly includes a driving member, a fixing plate and an adjustment seat, the driving member is connected to the fixing plate, the adjustment seat is detachably connected to the fixing plate and can be adjusted relative to the fixing plate; wherein the detection member is installed on the adjustment seat.

[0010] In one embodiment, one of the fixing plate and the adjustment seat is provided with an adjustment hole, and the other is provided with a fixing hole. The drive assembly further includes a fastener, which passes through the adjustment hole and the fixing hole and connects the fixing plate and the adjustment seat; wherein the adjustment hole is configured as a waist-shaped hole.

[0011] In one embodiment, the drive assembly further includes a housing, a first transmission wheel, a second transmission wheel and a transmission belt. The housing is provided on a side of the fixed plate away from the driving member and is connected to the fixed plate. The first transmission wheel, the second transmission wheel and the transmission belt are all installed in the housing; wherein, the first transmission wheel is connected to the output end of the driving member, the second transmission wheel is coaxially arranged with the driving wheel and connected to each other, and the transmission belt is wound around the first transmission wheel and the second transmission wheel and is in transmission connection with the first transmission wheel and the second transmission wheel.

[0012] In one embodiment, the driving component includes a motor rotor, and the detecting element is configured as a motor encoder. The motor encoder is connected to the driving component and is used to obtain a speed signal of the motor rotor.

[0013] In one embodiment, the motor rotor is connected to a second rotating shaft, and the fabric bone positioning structure further includes a transmission member, which is respectively connected to the second rotating shaft and the driving wheel, so that the motor rotor can drive the driving wheel to rotate through the transmission member.

[0014] The present application also provides a method for positioning a cloth bone position, which is implemented based on the cloth bone position positioning structure described in any one of the above embodiments. The method includes the following steps: starting a drive component and obtaining a speed signal at the output end of the drive component through a detection component; determining whether the speed signal at the output end of the drive component meets a preset value; if not, reducing the pulse frequency of the drive component, and maintaining it for a preset time before increasing the pulse frequency of the drive component again.

[0015] Compared with the existing technology, the fabric bone position positioning structure and fabric bone position positioning method provided by the present application, by setting a detection part and detecting the speed signal at the output end of the driving component, can detect whether the driving wheel is stuck and unable to rotate due to the high bone position, so that it can be discovered and adjusted more quickly, thereby effectively improving the efficiency of bone position positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 A schematic structural diagram of a sewing machine according to an embodiment of the present application;

[0018] Figure 2 This is a schematic structural diagram of the fabric bone positioning structure of Example 1 provided in this application;

[0019] Figure 3 This is an exploded view of the fabric bone positioning structure of Example 1 provided in this application;

[0020] Figure 4 This is a structural diagram of the fabric bone positioning structure of Example 2 provided in this application.

[0021] The symbols in the figure mean the following:

[0022] 100. Sewing machine; 10. Fabric bone position positioning structure; 11. Driving assembly; 111. Driving member; 1111. Second rotating shaft; 112. Transmission member; 1121. Housing; 1122. First transmission wheel; 1123. Second transmission wheel; 1124. Transmission belt; 113. Fixing plate; 1131. Fixing hole; 114. Adjusting seat; 1141. Adjusting hole; 115. Fastener; 12. Driving wheel; 121. Wheel body; 122. Detection disk; 1221. Detection rack; 123. First rotating shaft; 13. Detection member; 20. Drum; 30. Bone position detector; 31. Infrared light; 200. Fabric; 210. Bone position. DETAILED DESCRIPTION

[0023] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0024] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of this application are for illustrative purposes only and do not represent the only implementation method.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0026] In this application, unless otherwise expressly specified or limited, a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or that the first feature and the second feature are indirectly in contact through an intermediate medium. Furthermore, a first feature being “above,” “above,” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below,” “below,” or “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0027] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more of the relevant listed items.

[0028] Currently, sewing machines require the positioning of the fabric's joints during the sewing process, ensuring that the seam start position on the fabric maintains a certain distance from the joint to meet sewing requirements. Typically, sewing machines have an automatic joint-finding device. This device uses a stepper motor to drive a roller, which, through the cooperation of the roller and drum, drives the fabric to rotate. After the joint detection sensor detects the joint through an infrared light path, the roller is set to rotate to a specified angle and then stop, thereby positioning the joint on the fabric at the specified position.

[0029] To improve the efficiency of bone location search, stepper motors typically drive the rollers at higher speeds. However, because the faster the stepper motor, the smaller the output torque. This results in higher bone locations on the fabric creating significant resistance on the rollers, causing them to stop. This resistance, when transmitted to the stepper motor, causes the stepper motor to lose steps. Furthermore, the controller cannot detect when the stepper motor has lost steps and will continue to output high-speed rotation signals. This causes the stepper motor to remain out of step, causing the rollers to remain stopped, and thus preventing the bone location search from being completed properly.

[0030] See also Figures 1-4 The present application provides a fabric bone position locating structure 10, which is applied to a sewing machine 100 to solve the problem that existing sewing machines 100 cannot properly locate bone positions 210 when encountering high bone positions 210. The sewing machine 100 is equipped with two rollers 20, and a tubular fabric 200 is sleeved on the two rollers 20 to achieve stretching and tensioning, and can rotate with the rotation of the rollers 20. The sewing machine 100 is also equipped with a bone position detector 30, which can emit infrared light 31 to detect the bone positions 210 on the fabric 200.

[0031] Specifically, the fabric positioning structure 10 includes a drive assembly 11, a drive wheel 12, and a detector 13. The drive wheel 12 is connected to the output of the drive assembly 11 and is used to cooperate with the roller 20 to clamp the fabric 200, so that the drive assembly 11 can drive the drive wheel 12 to rotate and drive the fabric 200 to rotate synchronously. For example, the drive assembly 11 can drive the drive wheel 12 to rotate clockwise, while the roller 20 rotates counterclockwise, thereby driving the fabric 200 to rotate counterclockwise. The detector 13 is connected to the drive assembly 11 and is used to detect the speed signal at the output of the drive assembly 11.

[0032] It is understandable that when the driving wheel 12 encounters a higher bone position 210, the driving wheel 12 will encounter greater resistance and stop rotating. At this time, not only the rotation speed of the driving wheel 12 changes, but also the rotation speed of the output end of the driving component 11 also changes. Therefore, the present application sets a detection part 13, and by detecting the speed signal of the output end of the driving component 11, it can detect in a variable phase whether the driving wheel 12 is stuck and unable to rotate due to the high bone position 210, so that it can be discovered and adjusted more quickly, thereby effectively improving the efficiency of positioning the bone position 210.

[0033] It should be noted here that the driving part of the driving component 11 of the present application is mainly a stepper motor, which mainly includes a motor stator (not shown in the figure) and a motor rotor (not shown in the figure). Each time a pulse signal is input to the motor stator, the motor rotor will rotate a corresponding angle. Here, the speed of the motor rotor is proportional to the pulse frequency, but if the motor rotor cannot keep up with the changes in the pulse signal, the stepper motor will lose step.

[0034] The present application also provides a cloth bone positioning method, which is implemented based on the cloth bone positioning structure 10 and includes the following steps:

[0035] S1: Start the driving component 11 and obtain the speed signal of the output end of the driving component 11 through the detection component 13;

[0036] S2: Determine whether the speed signal at the output end of the driving component 11 meets the preset value;

[0037] S3: If not, reduce the pulse frequency of the driving component 11, maintain it for a preset time, and then increase the pulse frequency of the driving component 11 again.

[0038] It is easy to understand that when the speed signal at the output end of the drive assembly 11 does not meet the preset value, the drive wheel 12 becomes stuck due to the high bone position 210. At this time, by reducing the pulse frequency, the output torque of the drive assembly 11 can be increased. After maintaining this for a preset time, the drive wheel 12 can overcome the resistance of the bone position 210 and start rotating, driving the cloth 200 to resume rotation. In this way, the problem of the drive wheel 12 being stuck during the positioning of the bone position 210 is automatically eliminated. Afterwards, by increasing the pulse frequency again, the rotation speed can be increased again, so that the bone position 210 can be positioned more quickly, and the positioning efficiency of the bone position 210 is improved.

[0039] Here, the preset time can be reasonably set according to actual needs, as long as it can be ensured that within this time, the output torque of the driving component 11 can enable the driving wheel 12 to overcome the resistance of the bone position 210 and rotate, and at the same time avoid that the bone position 210 will not pass through the detection area of ​​the infrared light 31 on the bone position detector 30 during the re-rotation of the fabric 200.

[0040] In order to realize the detection of the speed signal of the output end of the driving component 11 by the detection member 13, the present application provides the following two embodiments, which are as follows:

[0041] Example 1

[0042] In this embodiment, if Figure 2 and Figure 3 As shown, the driving wheel 12 is provided with a detection rack 1221, and the detection rack 1221 rotates synchronously with the driving wheel 12. Among them, the detection member 13 is configured as a sensor, and the sensor and the detection rack 1221 are inductively matched. The sensor here can be a proximity sensor. It is easy to understand that when the driving wheel 12 rotates normally, the detection rack 1221 can periodically pass by the sensor. In this way, by analyzing the periodic matching time of the detection rack 1221 and the sensor, the rotational speed of the driving wheel 12 can be calculated, and compared with the predetermined rotational speed, it can be confirmed whether the driving wheel 12 is in a normal rotation state.

[0043] Furthermore, there are multiple detection racks 1221, and these multiple detection racks 1221 are evenly spaced along the circumference of the drive wheel 12. This allows the rotational state of the drive wheel 12 to be analyzed by detecting the time interval between two adjacent detection racks 1221 passing the sensor, with greater accuracy and detection efficiency. For example, the rotational speed of the drive wheel 12 can be calculated using the formula v = 60 / (n × t), where v represents the rotational speed of the drive wheel 12, n represents the number of detection racks 1221, and t represents the time interval between two adjacent detection racks.

[0044] In one embodiment, if Figure 3 As shown, the drive wheel 12 includes a wheel body 121, a detection disk 122, and a first rotating shaft 123. The wheel body 121 and the detection disk 122 are both mounted on and connected to the first rotating shaft 123. The first rotating shaft 123 is connected to the output end of the drive assembly 11. The wheel body 121 is used to cooperate with the drum 20 to rotate the fabric 200. Multiple detection racks 1221 are provided on the detection disk 122. This facilitates the processing of the detection racks 1221 and simplifies the connection, allowing for synchronous rotation of the detection racks 1221 and the wheel body 121.

[0045] However, the present invention is not limited thereto. In other embodiments, the detection disk 122 or the detection rack 1221 may also be directly connected to the wheel body 121 or formed on the wheel body 121, as long as the same cooperative detection effect can be achieved.

[0046] It should be noted here that since the first rotating shaft 123 is connected to the output end of the driving component 11, the driving wheel 12 can rotate at the same speed as the output end of the driving component 11. At this time, by detecting the detection rack 1221 on the driving wheel 12, the rotation speed of the output end of the driving component 11 can be obtained.

[0047] In one embodiment, if Figure 3 As shown, the drive assembly 11 includes a drive member 111, a transmission member 112, a fixed plate 113 and an adjustment seat 114. The drive member 111 is connected to the fixed plate 113, where the drive member 111 can be configured as a stepping motor. The transmission member 112 includes a housing 1121, a first transmission wheel 1122, a second transmission wheel 1123 and a transmission belt 1124. The housing 1121 is located on a side of the fixed plate 113 away from the drive member 111 and is connected to the fixed plate 113. The first transmission wheel 1122, the second transmission wheel 1123 and the transmission belt 1124 are all installed in the housing 1121. Among them, the first transmission wheel 1122 is connected to the output end of the drive member 111, the second transmission wheel 1123 is coaxially arranged with the drive wheel 112 and interconnected, and the transmission belt 1124 is wound around the first transmission wheel 1122 and the second transmission wheel 1123 and is in transmission connection with the first transmission wheel 1122 and the second transmission wheel 1123. That is, in this embodiment, the output end of the entire driving assembly 11 is the second transmission wheel 1123 , so that the driving member 111 can drive the driving wheel 12 to rotate through the transmission member 112 .

[0048] Furthermore, the adjustment seat 114 is detachably connected to the fixed plate 113 and can be adjusted relative to the fixed plate 113. The detection member 13 is mounted on the adjustment seat 114, and the first rotating shaft 123 is connected to the second transmission wheel 1123 after passing through the adjustment seat 114. In this way, the transmission belt 1124 can be tightened by adjusting the position of the adjustment seat 114 relative to the fixed plate 113, thereby ensuring a reliable connection between the transmission belt 1124 and the first transmission wheel 1122 and the second transmission wheel 1123. At the same time, the detection member 13 can change position with the adjustment seat 114, thereby maintaining an unchanged relative position with the wheel body 121 and the detection disk 122, so that the detection member 13 can better cooperate with the detection rack 1221, thereby improving the accuracy of the detection.

[0049] To achieve position adjustment between the adjustment seat 114 and the fixed plate 113, in one embodiment, one of the fixed plate 113 and the adjustment seat 114 is provided with an adjustment hole 1141, and the other is provided with a fixing hole 1131. The drive assembly 11 also includes a fastener 115, which passes through the adjustment hole 1141 and the fixing hole 1131 and connects the fixed plate 113 and the adjustment seat 114. The adjustment hole 1141 is configured as a waist-shaped hole, which is a combination of a rectangle and two semicircles. By configuring the adjustment hole 1141 as a waist-shaped hole, the convenience of adjusting the position of the adjustment seat 114 can be improved.

[0050] Of course, in other embodiments, a plurality of circular adjustment holes 1141 may be provided, and the position of the adjustment seat 114 may be adjusted by using the fastener 115 to penetrate different adjustment holes 1141 and cooperate with the fixing hole 1131 .

[0051] Optionally, in this embodiment, the fixing hole 1131 is formed in the fixing plate 113 , and the adjusting hole 1141 is formed in the adjusting seat 114 .

[0052] Example 2

[0053] In this embodiment, if Figure 4 As shown, the drive assembly 11 includes a motor rotor, and the detection component 13 is configured as a motor encoder. The motor encoder is connected to the drive assembly 11 and is used to obtain the speed signal of the motor rotor. The motor encoder generates a position signal of the motor rotor when the motor rotor rotates. The controller obtains the current speed signal of the motor rotor through the position signal. According to the speed signal, it can be determined in real time whether the stepper motor is out of step. For example, during the bone-finding process of the cloth 200, when the controller detects through the motor encoder that the speed of the motor rotor is reduced to a speed different from the preset speed, it can be determined that the stepper motor is out of step, that is, the driving wheel 12 encounters a high bone position 210 and causes a stall. At this time, the controller can increase the output torque of the drive assembly 11 by reducing the pulse frequency, thereby driving the cloth 200 to continue rotating.

[0054] Furthermore, the motor rotor is connected to a second rotating shaft 1111. The fabric positioning structure 10 also includes a transmission member 112, which is connected to the second rotating shaft 1111 and the drive wheel 12, respectively, so that the motor rotor can drive the drive wheel 12 to rotate via the transmission member 112. That is, in this embodiment, the output end of the drive assembly 11 is the motor rotor. Here, the transmission member 112 can have the same structure as the transmission member 112 in the first embodiment.

[0055] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of patent protection for the present application shall be determined by the appended claims.

Claims

1. A fabric bone positioning structure, characterized in that: It comprises a driving assembly (11), a driving wheel (12) and a detection member (13), wherein the driving wheel (12) is connected to the output end of the driving assembly (11) and is used to cooperate with the roller (20) to clamp the cloth (200), so that the driving assembly (11) can drive the driving wheel (12) to rotate and drive the cloth (200) to rotate synchronously; The detection member (13) is connected to the drive assembly (11), and the detection member (13) is used to detect a speed signal at an output end of the drive assembly (11).

2. The fabric bone positioning structure according to claim 1, characterized in that: A detection rack (1221) is provided on the driving wheel (12), and the detection rack (1221) rotates synchronously with the driving wheel (12); Wherein, the detection member (13) is configured as a sensor, and the sensor and the detection rack (1221) are inductively matched.

3. The fabric bone positioning structure according to claim 2, characterized in that: There are multiple detection racks (1221), and the multiple detection racks (1221) are evenly spaced and distributed along the circumference of the driving wheel (12).

4. The fabric bone positioning structure according to claim 3, characterized in that: The driving wheel (12) comprises a wheel body (121), a detection disk (122) and a first rotating shaft (123); the wheel body (121) and the detection disk (122) are both sleeved on and connected to the first rotating shaft (123); and the first rotating shaft (123) is connected to the output end of the driving assembly (11); Wherein, a plurality of the detection racks (1221) are all arranged on the detection disk (122).

5. The fabric bone positioning structure according to claim 2, characterized in that: The driving assembly (11) comprises a driving member (111), a fixing plate (113), and an adjusting seat (114); the driving member (111) is connected to the fixing plate (113); the adjusting seat (114) is detachably connected to the fixing plate (113) and can be adjusted relative to the fixing plate (113); Wherein, the detection member (13) is mounted on the adjustment seat (114).

6. The fabric bone positioning structure according to claim 5, characterized in that: One of the fixing plate (113) and the adjusting seat (114) is provided with an adjusting hole (1141), and the other is provided with a fixing hole (1131). The driving assembly (11) further comprises a fastener (115), the fastener (115) passing through the adjusting hole (1141) and the fixing hole (1131), and connecting the fixing plate (113) and the adjusting seat (114). Wherein, the adjustment hole (1141) is configured as a waist-shaped hole.

7. The fabric bone positioning structure according to claim 5, characterized in that: The driving assembly (11) further comprises a housing (1121), a first transmission wheel (1122), a second transmission wheel (1123) and a transmission belt (1124); the housing (1121) is arranged on a side of the fixing plate (113) away from the driving member (111) and is connected to the fixing plate (113); the first transmission wheel (1122), the second transmission wheel (1123) and the transmission belt (1124) are all installed in the housing (1121); The first transmission wheel (1122) is connected to the output end of the driving member (111), the second transmission wheel (1123) is coaxially arranged with the driving wheel (12) and connected to each other, and the transmission belt (1124) is wound around the first transmission wheel (1122) and the second transmission wheel (1123) and is transmission-connected to the first transmission wheel (1122) and the second transmission wheel (1123).

8. The fabric bone positioning structure according to claim 1, characterized in that: The drive assembly (11) includes a motor rotor, and the detection component (13) is configured as a motor encoder. The motor encoder is connected to the drive assembly (11) and is used to obtain a speed signal of the motor rotor.

9. The fabric bone positioning structure according to claim 8, characterized in that: A second rotating shaft (1111) is connected to the motor rotor, and the fabric bone position positioning structure further comprises a transmission member (112), wherein the transmission member (112) is respectively connected to the second rotating shaft (1111) and the driving wheel (12), so that the motor rotor can drive the driving wheel (12) to rotate via the transmission member (112).

10. A method for positioning fabric bones, characterized in that: Based on the fabric bone positioning structure according to any one of claims 1 to 9, the fabric bone positioning method comprises the following steps: Starting the driving component (11) and obtaining a speed signal from an output end of the driving component (11) through a detection component (13); Determining whether a speed signal at an output end of the drive component (11) meets a preset value; If not, the pulse frequency of the drive component (11) is reduced, and after maintaining the pulse frequency for a preset time, the pulse frequency of the drive component (11) is increased again.

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