Control circuit suitable for direct current brush motor electric cylinder

Abstract

The utility model discloses a control circuit suitable for a DC brush motor electric cylinder. The control circuit comprises a main circuit and a control loop. The main circuit comprises a direct-current power source I, a motor forward rotation circuit and a motor reverse rotation circuit, the motor forward rotation circuit and the motor reverse rotation circuit are connected with the direct-current power source I and the direct-current brush motor in series respectively, and stretching and retracting of a piston rod are achieved through forward rotation and reverse rotation of a motor shaft. The control loop comprises a direct-current power supply II, a plurality of self-locking buttons and a plurality of relays, a coil of one relay is connected in series with one self-locking button to form a branch, and the plurality of branches are connected in parallel and then connected in series with the direct-current power supply II; contacts of the plurality of relays are respectively connected in the main circuit so as to control forward and reverse rotation of the DC brush motor. Pure hardware control is adopted, programming is not needed, and the development cost is low; a stroke control circuit is designed and has a stroke limiting function; a double interlocking mechanism of a control circuit and a main circuit is adopted, and the operation reliability of the piston rod of the electric cylinder is guaranteed.

Description

Technical Field

[0001] This utility model relates to a pure hardware control circuit suitable for DC brushed motor electric cylinders, belonging to the field of electric cylinder technology. Background Technology

[0002] Electric cylinders are widely used in engineering equipment, medical devices, and other fields due to their environmental friendliness, superior controllability, and fast response speed. A significant portion of the motors used in these cylinders are currently brushed DC motors. Changing the direction of the current in the windings of a brushed DC motor switches the direction of the motor shaft, thus changing the linear motion direction of the piston rod in the electric cylinder. In electric cylinder control, the industry typically uses dedicated controllers. These controllers are powerful and can achieve complex controls under program instructions, but they are costly and often used for functions during trial operation, such as motor start-stop and piston rod extension / retraction, resulting in poor cost-effectiveness. Therefore, a low-cost, pure hardware control circuit suitable for brushed DC motor electric cylinders has been developed, which significantly improves the efficiency of dedicated controllers. Utility Model Content

[0003] To address the shortcomings of existing technologies, this utility model provides a control circuit suitable for DC brushed motor electric cylinders. It adopts pure hardware control, requires no programming, and has low development costs. A stroke control circuit is designed, which has the function of stroke limit. A dual interlocking mechanism of control circuit and main circuit is adopted to ensure the reliability of the electric cylinder piston rod operation.

[0004] This utility model is achieved according to the following technical solution:

[0005] A control circuit suitable for a DC brushed motor electric cylinder includes a main circuit and a control circuit;

[0006] The main circuit includes a DC power supply I, a motor forward rotation circuit, and a motor reverse rotation circuit. The motor forward rotation circuit and the motor reverse rotation circuit are connected in series with the DC power supply I and the DC brushed motor, respectively. The piston rod extends and retracts by rotating the motor shaft in both directions. An interlock circuit is formed between the motor forward rotation circuit and the motor reverse rotation circuit, with one circuit in the on state and the other circuit in the off state.

[0007] The control circuit includes a DC power supply II, multiple self-locking buttons, and multiple relays. The coil of one relay is connected in series with one self-locking button to form a branch. Multiple branches are connected in parallel and then connected in series with the DC power supply II. The contacts of the multiple relays are respectively connected in the main circuit to form a circuit for controlling the DC brushed motor to rotate forward or in reverse. An interlock circuit is formed between the branch for controlling the motor to rotate forward and the branch for controlling the motor to rotate in reverse, with one branch in a conducting state and the other branch in a disconnected state.

[0008] In some embodiments, at least one circuit breaker is connected in series in the main circuits of the motor forward rotation circuit, the motor reverse rotation circuit, and the control circuit.

[0009] In some embodiments, at least one fuse is connected in series in both the motor forward circuit and the motor reverse circuit.

[0010] In some embodiments, at least one ammeter is connected in series in both the motor forward rotation circuit and the motor reverse rotation circuit.

[0011] In some embodiments, the control circuit further includes two limit switches and two relays, which limit the extension and retraction of the piston rod.

[0012] In some embodiments, the limit switch II for detecting the piston rod extending to its limit position is connected in series with the coil of a relay KA5 to form a branch, and the normally closed contact I of the relay KA5 is connected in series in the motor forward rotation circuit.

[0013] A limit switch I, used to detect the piston rod retracting to its limit position, is connected in series with the coil of a relay KA4 to form a branch. The normally closed contact I of relay KA4 is connected in series in the motor reversing circuit.

[0014] In some embodiments, the plurality of self-locking buttons include self-locking button I, self-locking button II, and self-locking button III; the plurality of relays include relay KA1, relay KA2, and relay KA3.

[0015] In some embodiments, the self-locking button I, the normally closed contact II of relay KA2, and the coil of relay KA1 are connected in series to form a branch; the self-locking button II, the normally closed contact II of relay KA1, and the coil of relay KA2 are connected in series to form a branch; and the self-locking button III and the coil of relay KA3 are connected in series to form a branch.

[0016] In some embodiments, the normally open contact I of relay KA1 and the normally closed contact I of relay KA2 are connected in series in the forward rotation circuit of the motor; the normally open contact I of relay KA3, the normally closed contact I of relay KA1, and the normally open contact I of relay KA2 are connected in series in the reverse rotation circuit of the motor.

[0017] In some embodiments, the main circuit further includes connector I, connector II, and connector III; connector I is connected to the motor reversal circuit, connector II is connected to the motor forward circuit, and one end of connector III is connected to the motor forward circuit and the motor reversal circuit, while the other end is connected to the DC brushed motor.

[0018] Compared with the prior art, the advantages of this utility model are as follows:

[0019] 1. During the trial operation of the DC brushed motor electric cylinder, the dedicated controller was eliminated, thus improving the efficiency of the dedicated controller.

[0020] 2. Pure hardware circuit, no programming required, low development cost, and easy to operate;

[0021] 3. It has a stroke limit function to prevent damage to the electric cylinder body due to excessive stroke;

[0022] 4. For the extension or retraction process of the piston rod, a dual interlocking mechanism of the control circuit and the main circuit is adopted to improve the reliability of operation. Attached Figure Description

[0023] The accompanying drawings, as part of this utility model, are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not constitute an undue limitation of the present utility model. Obviously, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0024] In the attached diagram:

[0025] Figure 1 This is a schematic diagram of the main circuit of a control circuit for a DC brushed motor electric cylinder according to the present invention.

[0026] Figure 2 This is a schematic diagram of a control circuit for a DC brushed motor electric cylinder, according to the present invention.

[0027] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0029] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] like Figure 1 , Figure 2 As shown, a control circuit suitable for a DC brushed motor electric cylinder includes the following electrical components:

[0032] DC power supplies: DC power supply I1, DC power supply II30;

[0033] Circuit breakers: Circuit breaker I 2, Circuit breaker II 18, Circuit breaker III 19;

[0034] Fuse: Fuse I 4, Fuse II 16;

[0035] Ammeters: Ammeter I (5mm), Ammeter II (15mm);

[0036] Self-locking buttons: Self-locking button I 20, Self-locking button II 21, Self-locking button III 22;

[0037] Relay KA1: Relay KA1 normally closed contact I 8, Relay KA1 normally open contact I 9, Relay KA1 normally closed contact II 24, Relay KA1 coil 25;

[0038] Relay KA2: Relay KA2 normally closed contact I12, Relay KA2 normally open contact I13, Relay KA2 normally closed contact II23, Relay KA2 coil 26;

[0039] Relay KA3: Normally open contact I7 of relay KA3, coil 27 of relay KA3;

[0040] Relay KA4: Relay KA4 normally closed contact I3, Relay KA4 coil 28;

[0041] Relay KA5: Relay KA5 normally closed contact I17, relay KA5 coil 29;

[0042] Limit switches: Limit switch I 31, Limit switch II 32;

[0043] Connectors: Connector I 6, Connector II 14, Connector III 10;

[0044] Motor: DC brushed motor 11.

[0045] The connection relationships of the above electrical components will be further explained below.

[0046] Continue to refer to Figure 1 , Figure 2 As shown, the control circuit is divided into two parts: a main circuit and a control circuit. The main circuit includes a DC power supply I1, a motor forward rotation circuit, and a motor reverse rotation circuit. The motor forward rotation circuit and the motor reverse rotation circuit are connected in series with the DC power supply I1 and the DC brushed motor 11, respectively. The piston rod extends and retracts by rotating the motor shaft in both directions. An interlock circuit is formed between the motor forward rotation circuit and the motor reverse rotation circuit, with one circuit in a conducting state and the other in a disconnected state. The control circuit includes a DC power supply II30, multiple self-locking buttons, and multiple relays. The coil of one relay is connected in series with one self-locking button to form a branch. Multiple branches are connected in parallel and then connected in series with the DC power supply II30. The contacts of the multiple relays are connected in the main circuit to control the DC brushed motor 11 to rotate forward or in reverse. An interlock circuit is formed between the branch used to control the motor forward rotation and the branch used to control the motor reverse rotation, with one branch in a conducting state and the other in a disconnected state.

[0047] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, each of the main circuits of the motor forward rotation circuit, motor reverse rotation circuit, and control circuit has at least one circuit breaker connected in series, namely circuit breaker I2, circuit breaker II18, and circuit breaker III19 in the figure.

[0048] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, at least one fuse is connected in series in both the forward rotation circuit and the reverse rotation circuit of the motor, namely fuse I4 and fuse II16 in the figure.

[0049] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, at least one ammeter is connected in series in both the forward rotation circuit and the reverse rotation circuit of the motor, namely ammeter I5 and ammeter II15 in the figure.

[0050] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, the control circuit also includes two limit switches and two relays, which limit the extension and retraction of the piston rod.

[0051] Further plans will continue to be considered. Figure 1 , Figure 2As shown, a limit switch II 32, used to detect the piston rod extending to its limit position, is connected in series with a relay KA5 coil 29 to form a branch circuit. The normally closed contact I 17 of the relay KA5 is connected in series in the forward rotation circuit of the motor. A limit switch I 31, used to detect the piston rod retracting to its limit position, is connected in series with a relay KA4 coil 28 to form a branch circuit. The normally closed contact I 3 of the relay KA4 is connected in series in the reverse rotation circuit of the motor.

[0052] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, the multiple self-locking buttons include self-locking button I 20, self-locking button II 21, and self-locking button III 22; the multiple relays include relay KA1, relay KA2, and relay KA3.

[0053] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, the self-locking button I 20, the normally closed contact II 23 of relay KA2, and the coil 25 of relay KA1 are connected in series to form a branch; the self-locking button II 21, the normally closed contact II 24 of relay KA1, and the coil 26 of relay KA2 are connected in series to form a branch; the self-locking button III 22 and the coil 27 of relay KA3 are connected in series to form a branch.

[0054] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, normally open contact I9 of relay KA1 and normally closed contact I12 of relay KA2 are connected in series in the forward rotation circuit of the motor; normally open contact I7 of relay KA3, normally closed contact I8 of relay KA1 and normally open contact I13 of relay KA2 are connected in series in the reverse rotation circuit of the motor.

[0055] Further plans will continue to be considered. Figure 1 , Figure 2 As shown, the main circuit also includes connector I6, connector II14, and connector III10. Connector I6 is connected to the motor reversing circuit, connector II14 is connected to the motor forward circuit, and one end of connector III10 is connected to both the motor forward and reversing circuits, while the other end is connected to the DC brushed motor. Port A of connector III10 is electrically connected to ports A-1 and A-2, and port B of connector III10 is electrically connected to ports B-1 and B-2.

[0056] The operating principle of the control circuit for a DC brushed motor electric cylinder described above is given below.

[0057] like Figure 1 , Figure 2 As shown,

[0058] (1) The motor shaft rotates forward and the piston rod extends.

[0059] Circuit breakers III 19 and II 18 are closed. Pressing the self-locking button I20 energizes relay KA1 coil 25, closing KA1's normally open contact I9 and opening normally closed contacts I8 and II 24. Current flows from the DC power supply port U2+, through fuse II 16 and ammeter II 15, through ports A on both sides of connector II 14, and through the closed normally open contact I9 of KA1 to connector III 10. Current flows into connector III 10 from port A-1, out from port A, into the positive terminal of motor 11, out from the negative terminal of motor 11, to port B of connector III 10, and through port B-2 to the normally closed contact I12 of relay KA2. Current flows out from the normally closed contact I12 of KA2, through ports B on both sides of connector II, and back to the DC power supply port U2-, forming a closed circuit. Figure 1 The dotted-lined portion of the main circuit is shown. Current flows in from the positive terminal of motor 11 and flows out from the negative terminal of motor 11. The motor shaft rotates clockwise, at which time the piston rod extends.

[0060] Current flows into connector III10 from terminal A-1. Because terminal A-2 is connected to the normally open contact I13 of KA2, a closed circuit cannot be formed, so current will not flow out from terminal A-2. Current flows into connector III10 from terminal A-1. Because terminal B-1 of connector III10 is connected to the normally closed contact I8 of relay KA1, which is now disconnected, a closed circuit cannot be formed, so current will not flow out from terminal B-1.

[0061] When the self-locking button I20 is released, the coil 25 of relay KA1 is de-energized, the normally open contact I9 of KA1, which was already closed, opens, and the normally closed contacts I8 and II24, which were already open, close. The motor loses power and decelerates until it stops.

[0062] (2) The motor shaft reverses and the piston rod retracts.

[0063] Circuit breaker III 19 and circuit breaker I 2 are closed. Self-locking buttons III 22 and II 21 are pressed. With self-locking button II 21 pressed, relay KA2 coil 26 is energized, KA2 normally open contact I 13 closes, normally closed contact I 12 opens, and normally closed contact II 23 opens. With self-locking button III 22 pressed, KA3 coil 27 is energized, and relay KA3 normally open contact I 7 closes. Current flows from the U1+ terminal of DC power supply I, through circuit breaker I 2, fuse I 4, ammeter I 5, through the A ports on both sides of connector I 6, the normally open contact I 7 of relay KA3 (already closed), and the normally closed contact I 8 of relay KA1, flowing to connector III 10. Current flows in from terminal B-1 of connector III10, flows out from terminal B, flows into the negative terminal of motor 11, flows out from the positive terminal of motor 11, flows to terminal A of connector III10, and then flows through terminal A-2 to the normally open contact I13 of relay KA2, which is now closed. Current flows out from the normally open contact I13 of relay KA2, flows through the B ports at both ends of connector I6, and returns to the U1- terminal of DC power supply I, forming a closed loop. This is shown by the solid lines in the diagram. Current flows in from the negative terminal of motor 11 and flows out from the positive terminal of motor 11, causing the motor shaft to reverse, at which point the piston rod retracts.

[0064] Current flows into connector III10 from terminal B-1. Because the normally closed contact I12 of relay KA2, which is connected to terminal B-2, is open, a closed circuit cannot be formed, so current will not flow out from terminal B-2. Current flows into connector III10 from terminal B-1. Because the normally open contact I9 of relay KA1, which is connected to terminal A-1, is open, a closed circuit cannot be formed, so current will not flow out from terminal A-1.

[0065] Release the self-locking button Ⅲ22, then release it again and press the self-locking button Ⅱ21. The normally open contacts of relays KA2 and KA3 that were closed will open, and the normally closed contacts that were open will close. The motor will lose power and decelerate until it stops.

[0066] (3) Travel limit

[0067] DC brushed motor electric cylinders are generally equipped with limit switches at both ends of the stroke to limit the travel.

[0068] When the piston rod extends to its limit position, limit switch II 32 in the control circuit closes, energizing coil 29 of relay KA5, and normally closed contact I 17 of KA5 opens. The motor shaft's forward rotation circuit in the main circuit is disconnected, causing the motor to lose power and decelerate until it stops. When the piston rod retracts, moving away from its extension limit position, limit switch II 32 opens, coil 29 of relay KA5 is de-energized, and normally closed contact I 17 of KA5 returns to its closed state.

[0069] When the piston rod retracts to its limit position, limit switch I31 in the control circuit closes, energizing coil 28 of relay KA4, and normally closed contact I3 of KA4 opens. The motor shaft reversal circuit in the main circuit is disconnected, causing the motor to lose power and decelerate until it stops. When the piston rod extends, moving away from its retracted limit position, limit switch I31 opens, coil 28 of relay KA4 is de-energized, and normally closed contact I3 of KA4 returns to its closed state.

[0070] (4) Double interlock

[0071] Interlock function of control circuit:

[0072] When the self-locking button I20 is pressed, the coil 25 of relay KA1 is energized, the normally closed contact of KA1 opens, and the normally open contact closes, extending the piston rod. At this time, the normally closed contact II24 of relay KA1 opens, and the coil 26 of KA2 in the control circuit is de-energized. Even if the self-locking button II21 is pressed due to a malfunction, the coil 26 of KA2 will not be energized. One of the prerequisites for the piston rod to retract is that the coil 26 of KA2 is energized. Therefore, the piston rod will not retract due to a malfunction when it extends.

[0073] When the piston rod retracts, the normally closed contact II23 of relay KA2 is open, and the coil 25 of relay KA1 in the control circuit is de-energized. Even if the self-locking button I20 is pressed due to a malfunction, the coil 25 of relay KA1 will not be energized. The prerequisite for the piston rod to extend is that the coil 25 of relay KA1 is energized. Therefore, the piston rod will not extend due to a malfunction when it retracts.

[0074] Interlocking function of the main circuit:

[0075] The normally open contact I9 of relay KA1 and the normally closed contact I12 of relay KA2 jointly control the on / off state of the circuit when the piston rod extends. When both normally open contact I9 of relay KA1 and normally closed contact I12 of relay KA2 are closed, the circuit is open, and the piston rod extends. The normally open contact I13 of relay KA2 and normally closed contact I8 of relay KA1 jointly control the on / off state of the circuit when the piston rod retracts. When normally open contact I7 of relay KA3 is closed, and normally open contact I13 of relay KA2 and normally closed contact I8 of relay KA1 are also closed, the circuit is open, and the piston rod retracts. When the normally open contact of the same relay is closed, the normally closed contact must be open. Therefore, the wiring connection of the main circuit forms an interlock for the extension and retraction of the electric cylinder.

[0076] In summary, this utility model provides a control circuit suitable for DC brushed motor electric cylinders, achieving the following functions and effects:

[0077] 1. Verify whether the DC brushed motor electric cylinder is running normally by building a pure hardware circuit;

[0078] 2. A self-locking button in conjunction with a relay is used to control the extension and retraction of the electric cylinder piston rod and the start and stop of the motor;

[0079] 3. A dual interlocking mechanism for the main circuit and control circuit is adopted to ensure the reliable operation of the electric cylinder piston rod;

[0080] 4. An ammeter is connected in the circuit for real-time current monitoring, and a fuse is connected for short-circuit protection.

[0081] 5. The control circuit is designed to work in conjunction with the limit switch on the electric cylinder to limit the travel.

[0082] 6. The circuit is equipped with a circuit breaker, which can be manually disconnected in case of circuit abnormality to protect the motor and power supply.

[0083] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0084] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features found in other embodiments but not others, combinations of features from different embodiments are also within the scope of protection of this invention and form different embodiments. For example, in the embodiments described above, those skilled in the art can use them in combination based on known technical solutions and the technical problems to be solved by this application.

[0085] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A control circuit suitable for a DC brushed motor electric cylinder, characterized in that: Includes the main circuit and the control loop; The main circuit includes a motor forward rotation circuit and a motor reverse rotation circuit. The motor forward rotation circuit and the motor reverse rotation circuit are powered by DC power supply I to drive a DC brushed motor. The piston rod extends and retracts by rotating the motor shaft in both directions. An interlock circuit is formed between the motor forward rotation circuit and the motor reverse rotation circuit, with one circuit in the on state and the other circuit in the off state. The control circuit includes a DC power supply II, multiple self-locking buttons, and multiple relays. The coil of one relay is connected in series with one self-locking button to form a branch. Multiple branches are connected in parallel and then connected in series with the DC power supply II. The contacts of the multiple relays are respectively connected in the main circuit to form a circuit for controlling the DC brushed motor to rotate forward or in reverse. An interlock circuit is formed between the branch for controlling the motor to rotate forward and the branch for controlling the motor to rotate in reverse, with one branch in a conducting state and the other branch in a disconnected state.

2. The control circuit for a DC brushed motor electric cylinder according to claim 1, characterized in that: At least one circuit breaker is connected in series in the main circuits of the motor forward rotation circuit, the motor reverse rotation circuit, and the control circuit.

3. The control circuit for a DC brushed motor electric cylinder according to claim 1, characterized in that: At least one fuse is connected in series in both the motor forward rotation circuit and the motor reverse rotation circuit.

4. The control circuit for a DC brushed motor electric cylinder according to claim 1, characterized in that: At least one ammeter is connected in series in both the motor forward rotation circuit and the motor reverse rotation circuit.

5. A control circuit for a DC brushed motor electric cylinder according to claim 1, characterized in that: The control circuit also includes two limit switches and two relays, which limit the extension and retraction of the piston rod.

6. A control circuit for a DC brushed motor electric cylinder according to claim 5, characterized in that: Limit switch II, used to detect the piston rod extending to its limit position, is connected in series with the coil of relay KA5 to form a branch. The normally closed contact I of relay KA5 is connected in series in the motor forward rotation circuit. A limit switch I, used to detect the piston rod retracting to its limit position, is connected in series with the coil of a relay KA4 to form a branch. The normally closed contact I of relay KA4 is connected in series in the motor reversing circuit.

7. A control circuit for a DC brushed motor electric cylinder according to claim 1, characterized in that: The plurality of self-locking buttons include self-locking button I, self-locking button II, and self-locking button III; the plurality of relays include relay KA1, relay KA2, and relay KA3.

8. A control circuit for a DC brushed motor electric cylinder according to claim 7, characterized in that: The self-locking button I, the normally closed contact II of relay KA2, and the coil of relay KA1 are connected in series to form a branch; the self-locking button II, the normally closed contact II of relay KA1, and the coil of relay KA2 are connected in series to form a branch; the self-locking button III and the coil of relay KA3 are connected in series to form a branch.

9. A control circuit for a DC brushed motor electric cylinder according to claim 8, characterized in that: The normally open contact I of relay KA1 and the normally closed contact I of relay KA2 are connected in series in the forward rotation circuit of the motor; the normally open contact I of relay KA3, the normally closed contact I of relay KA1, and the normally open contact I of relay KA2 are connected in series in the reverse rotation circuit of the motor.

10. A control circuit for a DC brushed motor electric cylinder according to claim 1, characterized in that: The main circuit also includes connector I, connector II and connector III; connector I is connected to the motor reverse circuit, connector II is connected to the motor forward circuit, and one end of connector III is connected to the motor forward circuit and the motor reverse circuit, while the other end is connected to the DC brushed motor.

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