Front and back control module, control circuit and truss crane

Abstract

The utility model discloses a front and back control module, a control circuit and a joist barrow crane, and belongs to the field of joist barrow cranes. One end of the frequency converter is connected with the first motor, the other end of the frequency converter is used for being connected with an alternating current power supply, the frequency converter is provided with a common terminal, a forward rotation terminal and a reverse rotation terminal, the common terminal and the forward rotation terminal are connected through a first normally open contact, and the common terminal and the reverse rotation terminal are connected through a second normally open contact; the forward control sub-circuit comprises a first normally open button and a first coil which are connected in series; the backward control sub-circuit comprises a second normally open button and a second coil which are connected in series; wherein the forward control sub-circuit and the backward control sub-circuit are connected in parallel and then are connected with an alternating current power supply. The utility model has the technical effect that the harmony of the load gear and the power gear is good.

Description

TECHNICAL FIELD

[0001] The utility model relates to a truss crane, especially to a front and back control module, a control circuit and a truss crane. BACKGROUND

[0002] The truss crane is a kind of hoisting equipment that is across workshop, warehouse or material field and carries out material hoisting, which has the advantages of high operation efficiency and wide operation range.

[0003] But the relevant truss crane when working, power gear drives load gear, because of big load, it is easy to cause the slow start speed of load gear, and power gear starts fast, thus leading to the poor harmony of load gear and power gear, when stopping, power gear stops quickly, and load gear still moves quickly due to inertia, again leading to the poor harmony of load gear and power gear. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a front and back control module, which is convenient for making the harmony of load gear and power gear good, and also aims at providing a control circuit and a truss crane.

[0005] Technical scheme

[0006] A front and back control module, comprising:

[0007] A first motor;

[0008] A frequency converter, one end of the frequency converter is connected with the first motor, the other end of the frequency converter is used to be connected with an alternating current power supply, the frequency converter has a common terminal, a positive rotation terminal and a reverse rotation terminal, the common terminal and the positive rotation terminal are connected through a first normally open contact, and the common terminal and the reverse rotation terminal are connected through a second normally open contact;

[0009] A forward control sub-circuit, comprising a first normally open button and a first coil connected with each other in series;

[0010] A backward control sub-circuit, comprising a second normally open button and a second coil connected with each other in series;

[0011] Wherein, the forward control sub-circuit and the backward control sub-circuit are connected in parallel and used to be connected with the alternating current power supply.

[0012] Optionally,

[0013] The forward control sub-circuit further comprises a first normally closed contact connected with the first normally open button and the first coil in series;

[0014] The backward control sub-circuit further comprises a second normally closed contact connected with the second normally open button and the second coil in series.

[0015] The first normally closed contact and the second normally closed contact are interlocked.

[0016] Optionally,

[0017] The forward control sub-circuit further comprises a first limit switch connected in series with the first normally open button and the first coil.

[0018] The backward control sub-circuit further comprises a second limit switch connected in series with the second normally open button and the second coil.

[0019] Optionally, a first fuse is connected in series with the forward control sub-circuit and the backward control sub-circuit in parallel, and is used to be connected with the AC power supply.

[0020] Optionally, a first air switch is connected at one end of the frequency converter, and the other end of the first air switch is used to be connected with the AC power supply.

[0021] A control circuit comprising a forward-backward control module, further comprising:

[0022] A left-right control module used to be connected with the AC power supply.

[0023] An up-down control module used to be connected with the AC power supply.

[0024] Optionally, the up-down control module comprises:

[0025] A third motor, a first overload thermal relay, a second overload thermal relay, a third overload thermal relay, a fifth contactor, and a sixth contactor, the third motor is connected to the fifth contactor through the first overload thermal relay, the second overload thermal relay, and the third overload thermal relay, the fifth contactor is used to be connected with the AC power supply, the third motor is also connected to the sixth contactor through the first overload thermal relay, the second overload thermal relay, and the third overload thermal relay, and the sixth contactor is used to be connected with the AC power supply.

[0026] An upward control sub-circuit comprising a fifth normally open button, a fifth normally closed contact, a fifth limit switch, and a fifth coil connected in series.

[0027] A downward control sub-circuit comprising a sixth normally open button, a sixth normally closed contact, a sixth limit switch, and a sixth coil connected in series.

[0028] The one end of the series connection of the normally closed contact of the first overload thermal relay, the normally closed contact of the second overload thermal relay and the normally closed contact of the third overload thermal relay is connected to the upward control sub-circuit and the downward control sub-circuit which are connected in parallel with each other, and the other end is used for being connected with the alternating current power supply; the upward control sub-circuit and the downward control sub-circuit which are connected in parallel with each other are also used for being connected with the alternating current power supply; the fifth normally closed contact and the sixth normally closed contact are interlocked.

[0029] Optionally, the upward and downward control module further comprises:

[0030] The other end of the series connection of the normally closed contact of the first overload thermal relay, the normally closed contact of the second overload thermal relay and the normally closed contact of the third overload thermal relay is connected with the alternating current power supply through the third fuse;

[0031] The third air switch has one end connected with the fifth contactor and the sixth contactor, and the other end used for being connected with the alternating current power supply.

[0032] Optionally, the left and right control module comprises:

[0033] The third contactor has one end connected with the second motor and the second thermal relay, and the other end connected with the alternating current power supply through the second air switch; the fourth contactor has one end connected with the second motor and the second thermal relay, and the other end connected with the alternating current power supply through the second air switch;

[0034] The left control sub-circuit comprises a third normally open button, a third normally closed contact, a third limit switch and a third coil which are connected in series.

[0035] The right control sub-circuit comprises a fourth normally open button, a fourth normally closed contact, a fourth limit switch and a fourth coil which are connected in series.

[0036] The one end of the normally closed contact of the second thermal relay is connected with the left control sub-circuit and the right control sub-circuit which are connected in parallel with each other, and the other end is connected with the alternating current power supply through the second fuse; the left control sub-circuit and the right control sub-circuit which are connected in parallel with each other are also connected with the alternating current power supply; the third normally closed contact and the fourth normally closed contact are interlocked.

[0037] A kind of truss car hoist, comprising a control circuit.

[0038] Beneficial effects:

[0039] (1) the first motor is positively rotated under the action of the frequency converter, so as to reduce the starting speed of the power gear and ensure the harmony of the load gear and the power gear, when stopping, the frequency converter can also reduce the stopping speed of the power gear, so as to ensure the harmony of the load gear and the power gear; the first motor is reversely rotated under the action of the frequency converter, so as to reduce the starting speed of the power gear and ensure the harmony of the load gear and the power gear, when stopping, the frequency converter can also reduce the stopping speed of the power gear, so as to ensure the harmony of the load gear and the power gear;

[0040] (2) if the fifth limit switch or the sixth limit switch fails, causes the upward or downward movement to exceed the preset distance, the first overload thermal relay, the second overload thermal relay and the third overload thermal relay act immediately, so that the normally closed contact, the normally closed contact and the normally closed contact are disconnected, so as to ensure good sensitivity. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 it is a control circuit schematic view of the embodiment 1 of the utility model;

[0042] Figure 2 it is the schematic view of the frequency converter of the embodiment 1 of the utility model. DETAILED DESCRIPTION

[0043] In order to make the technical scheme of the utility model more clear, the utility model is further explained in detail in combination with the drawings and specific embodiments.

[0044] The application will be described in further detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related utility model, and not to limit the utility model. In addition, it should be noted that only parts related to the utility model are shown in the drawings for ease of description. The first, second, and the like in the utility model are set for the convenience of describing the technical solutions of the utility model, and have no specific limiting effect, and all refer to the technical solutions of the utility model. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. In the description of the utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model. In addition, the terms "first", "second", "third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance. Unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances. The multiple technical solutions in the same embodiment and the multiple technical solutions of different embodiments can be arranged and combined to form new technical solutions without contradiction or conflict, which are within the scope of the utility model.

[0045] Embodiment 1

[0046] As Figures 1-2 , the embodiment provides a forward and backward control module, which comprises a first motor M1; a frequency converter VFD, one end of the frequency converter VFD is connected with the first motor M1, the other end of the frequency converter VFD is used for being connected with an alternating current power supply, the frequency converter VFD has a common terminal COM, a forward rotation terminal DI1 and a reverse rotation terminal DI2, the common terminal COM and the forward rotation terminal DI1 are connected through a first normally open contact KM12, the common terminal COM and the reverse rotation terminal DI2 are connected through a second normally open contact KM22; a forward control sub-circuit, comprising a first normally open button SB1 and a first coil KM14 connected with each other in series; a backward control sub-circuit, comprising a second normally open button SB2 and a second coil KM24 connected with each other in series; wherein the forward control sub-circuit and the backward control sub-circuit are connected in parallel and used for being connected with the alternating current power supply.

[0047] Specifically, when needing to move forward, the first normally open button SB1 is pressed, so that the first coil KM14 is electrified, thereby causing the first normally open contact KM12 to be attracted, and further causing the common terminal COM and the forward rotation terminal DI1 to be in communication, and finally causing the first motor M1 to rotate forward under the action of the frequency converter VFD, so as to facilitate reducing the starting speed of the power gear and ensuring the harmony of the load gear and the power gear; when stopping, the frequency converter VFD can also reduce the stopping speed of the power gear, so as to ensure the harmony of the load gear and the power gear;

[0048] When needing to move backward, the second normally open button SB2 is pressed, so that the second coil KM24 is electrified, thereby causing the second normally open contact KM22 to be attracted, and further causing the common terminal COM and the reverse rotation terminal DI2 to be in communication, and finally causing the first motor M1 to rotate backward under the action of the frequency converter VFD, so as to facilitate reducing the starting speed of the power gear and ensuring the harmony of the load gear and the power gear; when stopping, the frequency converter VFD can also reduce the stopping speed of the power gear, so as to ensure the harmony of the load gear and the power gear;

[0049] Preferably, the first motor M1 is a three-phase motor; and the frequency converter VFD is preferably a Delixi e180 series.

[0050] Further, as shown in Figure 1 , the forward control sub-circuit further comprises a first normally closed contact KM11 connected in series with the first normally open button SB1 and the first coil KM14; and the backward control sub-circuit further comprises a second normally closed contact KM21 connected in series with the second normally open button SB2 and the second coil KM24; wherein the first normally closed contact KM11 and the second normally closed contact KM21 are interlocked.

[0051] Specifically, the interlocking means that the first normally closed contact KM11 and the second normally closed contact KM21 cannot be in the closed state at the same time, so as to facilitate preventing the forward control sub-circuit and the backward control sub-circuit from being short-circuited; when needing to move forward, the first normally closed contact KM11 is closed and the second normally closed contact KM21 is opened; when needing to move backward, the first normally closed contact KM11 is opened and the second normally closed contact KM21 is closed.

[0052] Further, as shown in Figure 1 , the forward control sub-circuit further comprises a first limit switch SQ1 connected in series with the first normally open button SB1 and the first coil KM14; and the backward control sub-circuit further comprises a second limit switch SQ2 connected in series with the second normally open button SB2 and the second coil KM24.

[0053] Specifically, when moving forward beyond a preset distance, the first limit switch SQ1 is opened, thereby achieving stopping; when moving backward beyond a preset distance, the second limit switch SQ2 is opened, thereby achieving stopping; and the first limit switch SQ1 and the second limit switch SQ2 can be in the form of direct-acting type or rolling type.

[0054] Further, as Figure 1 It also includes a first fuse FU1, which is connected in series with the forward control sub-circuit and the backward control sub-circuit in parallel, and is used to be connected with the AC power supply. Specifically, the first fuse FU1 is used for overcurrent protection, and the first fuse FU1 can be in the form of fast-fuse, slow-fuse, etc.

[0055] Further, as Figure 1 It also includes a first air switch QF1, one end of which is connected with the other end of the frequency converter VFD, and the other end of the first air switch QF1 is used to be connected with the AC power supply. Specifically, the first air switch QF1 is used for overcurrent protection, and the first air switch QF1 can be in the form of thermal magnetic tripping, electronic tripping, etc.

[0056] As Figure 1 The embodiment also provides a control circuit, which includes the forward-backward control module of the embodiment, and further includes: a left-right control module used to be connected with the AC power supply; and an up-down control module used to be connected with the AC power supply. Specifically, the left-right control module is used to realize left and right control; and the up-down control module is used to realize up and down control.

[0057] Further, as Figure 1 The up-down control module includes:

[0058] The third motor M3, the first overload thermal relay KJ1, the second overload thermal relay KJ2, the third overload thermal relay KJ3, the fifth contactor KM5, and the sixth contactor KM6, the third motor M3 is connected to the fifth contactor KM5 through the first overload thermal relay KJ1, the second overload thermal relay KJ2, and the third overload thermal relay KJ3, the fifth contactor KM5 is used to be connected with the AC power supply, and the third motor M3 is also connected to the sixth contactor KM6 through the first overload thermal relay KJ1, the second overload thermal relay KJ2, and the third overload thermal relay KJ3, the sixth contactor KM6 is used to be connected with the AC power supply;

[0059] The up control sub-circuit includes a fifth normally open button SB5, a fifth normally closed contact KM51, a fifth limit switch SQ5, and a fifth coil KM52 connected in series.

[0060] The down control sub-circuit includes a sixth normally open button SB6, a sixth normally closed contact KM61, a sixth limit switch SQ6, and a sixth coil KM62 connected in series.

[0061] The one end of the series connection of the normally closed contact KJ11 of the first overload thermal relay KJ1, the normally closed contact KJ21 of the second overload thermal relay KJ2 and the normally closed contact KJ31 of the third overload thermal relay KJ3 is connected to the upward control sub-circuit and the downward control sub-circuit which are in parallel with each other, and the other end is used for being connected with the alternating current power supply; the upward control sub-circuit and the downward control sub-circuit which are in parallel with each other are also used for being connected with the alternating current power supply; the fifth normally closed contact KM51 and the sixth normally closed contact KM61 are interlocked.

[0062] Specifically, when upward movement is needed, the fifth normally closed contact KM51 is kept closed, the fifth normally open button SB5 is pressed, the fifth coil KM52 is powered, the fifth contact KM5 is attracted, and the third motor M3 is rotated in the positive direction; when downward movement is needed, the sixth normally closed contact KM61 is kept closed, the sixth normally open button SB6 is pressed, the sixth coil KM62 is powered, the sixth contact KM6 is attracted, and the third motor M3 is rotated in the negative direction.

[0063] The third motor M3 is preferably a three-phase motor; if the fifth limit switch SQ5 or the sixth limit switch SQ6 fails, causing the upward or downward movement to exceed the preset distance, the first overload thermal relay KJ1, the second overload thermal relay KJ2 and the third overload thermal relay KJ3 act immediately to disconnect the normally closed contact KJ11, the normally closed contact KJ21 and the normally closed contact KJ31, thereby ensuring good sensitivity; the interlocking means that the fifth normally closed contact KM51 and the sixth normally closed contact KM61 cannot be in the closed state at the same time, thereby preventing the upward control sub-circuit and the downward control sub-circuit from being short-circuited; when the upward movement exceeds the preset distance, the fifth limit switch SQ5 is disconnected, thereby stopping the machine; when the downward movement exceeds the preset distance, the sixth limit switch SQ6 is disconnected, thereby stopping the machine; the fifth limit switch SQ5 and the sixth limit switch SQ6 can be of the direct-acting type, the rolling type, etc.

[0064] Further, as shown in FIG. 1, the upward control sub-circuit and the downward control sub-circuit each include a first overload thermal relay KJ1, a second overload thermal relay KJ2, a third overload thermal relay KJ3, a fifth normally closed contact KM51, a sixth normally closed contact KM61, a fifth normally open button SB5, a sixth normally open button SB6, a fifth limit switch SQ5, a sixth limit switch SQ6, a fifth contact KM5, a sixth contact KM6, a fifth coil KM52, a sixth coil KM62, a first normally closed contact KJ11, a second normally closed contact KJ21, a third normally closed contact KJ31, a first overload thermal relay KJ1, a second overload thermal relay KJ2, a third overload thermal relay KJ3, a fifth normally closed contact KM51, a sixth normally closed contact KM61, a fifth normally open button SB5, a sixth normally open button SB6, a fifth limit switch SQ5, a sixth limit switch SQ6, a fifth contact KM5, a sixth contact KM6, a fifth coil KM52, a sixth coil KM62, a first normally closed contact KJ11, a second normally closed contact KJ21 and a third normally closed contact KJ31. Figure 1 The upward control sub-circuit and the downward control sub-circuit each further include a third fuse FU3, the other end of the series connection of the normally closed contact KJ11 of the first overload thermal relay KJ1, the normally closed contact KJ21 of the second overload thermal relay KJ2 and the normally closed contact KJ31 of the third overload thermal relay KJ3 is connected with the alternating current power supply through the third fuse FU3; a third air switch QF3, one end of the third air switch QF3 is connected with the fifth contact KM5 and the sixth contact KM6, and the other end of the third air switch QF3 is used for being connected with the alternating current power supply.

[0065] Specifically, the third fuse FU3 and the third air switch QF3 are used for overcurrent protection; the third fuse FU3 can be of the fast-fuse type, the slow-fuse type, etc.; and the third air switch QF3 can be of the thermal-magnetic tripping type, the electronic tripping type, etc.

[0066] Further, the left and right control module comprises: Figure 1

[0067] The second motor M2, the second thermal relay FR2, the third contactor KM3 and the fourth contactor KM4, one end of the third contactor KM3 is connected through the second thermal relay FR2 and the second motor M2, the other end of the third contactor KM3 is connected through the second air switch QF2 for connecting with the alternating current power supply, one end of the fourth contactor KM4 is connected through the second thermal relay FR2 and the second motor M2, the other end of the fourth contactor KM4 is connected through the second air switch QF2 for connecting with the alternating current power supply;

[0068] The left control sub-circuit comprises the third normally open button SB3, the third normally closed contact KM31, the third limit switch SQ3 and the third coil KM32 connected in series;

[0069] The right control sub-circuit comprises the fourth normally open button SB4, the fourth normally closed contact KM41, the fourth limit switch SQ4 and the fourth coil KM42 connected in series;

[0070] One end of the normally closed contact FR21 of the second thermal relay FR2 is connected with the left control sub-circuit and the right control sub-circuit in parallel, the other end of the normally closed contact FR21 of the second thermal relay FR2 is connected through the second fuse FU2 for connecting with the alternating current power supply, the left control sub-circuit and the right control sub-circuit in parallel are also used for connecting with the alternating current power supply, and the third normally closed contact KM31 and the fourth normally closed contact KM41 are interlocked.

[0071] Specifically, when needing to turn left, the third normally closed contact KM31 is kept closed, the third normally open button SB3 is pressed, the third coil KM32 is powered, the third contactor KM3 is attracted, and then the second motor M2 is rotated in the positive direction; when needing to turn right, the fourth normally closed contact KM41 is kept closed, the fourth normally open button SB4 is pressed, the fourth coil KM42 is powered, the fourth contactor KM4 is attracted, and then the second motor M2 is rotated in the reverse direction.

[0072] ​Wherein, the second motor M2 is preferably a three-phase motor; if the third limit switch SQ3 or the fourth limit switch SQ4 fails, resulting in moving more than a preset distance to the left or to the right, the second thermal relay FR2 slowly acts, so that the normally closed contact FR21 is disconnected; interlocking, that is, the third normally closed contact KM31 and the fourth normally closed contact KM41 cannot be in the closed state at the same time, facilitating preventing the left control sub-circuit and the right control sub-circuit from short-circuiting; when moving more than a preset distance to the left, the third limit switch SQ3 is disconnected, thereby achieving shutdown; when moving more than a preset distance to the right, the fourth limit switch SQ4 is disconnected, thereby achieving shutdown; the third limit switch SQ3 and the fourth limit switch SQ4 can be in the form of direct-acting type, rolling type, etc.

[0073] As Figure 1 Figure 1 The embodiment also provides a derrick crane, which comprises the control circuit.

[0074] The above embodiments only express several implementation manners of the utility model, and the description is more specific and detailed, but it cannot be understood as the limitation of the utility model patent scope. It should be pointed out that, for ordinary skilled persons in the art, without departing from the concept of the utility model, a number of modifications and improvements can be made, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent should be subject to the appended claims.

Claims

1. A front and rear control module, characterized by, Comprise: A first motor (M1); A frequency converter (VFD), one end of which is connected with the first motor (M1), the other end of which is used for connecting with an alternating current power supply, the frequency converter (VFD) having a common terminal (COM), a forward rotation terminal (DI1) and a reverse rotation terminal (DI2), the common terminal (COM) and the forward rotation terminal (DI1) being connected through a first normally open contact (KM12), the common terminal (COM) and the reverse rotation terminal (DI2) being connected through a second normally open contact (KM22); A forward control sub-circuit comprising a first normally open button (SB1) and a first coil (KM14) connected in series with each other; A backward control sub-circuit comprising a second normally open button (SB2) and a second coil (KM24) connected in series with each other; Wherein, the forward control sub-circuit and the backward control sub-circuit are connected in parallel and used for connecting with the alternating current power supply.

2. The forward and backward control module according to claim 1, wherein: The forward control sub-circuit further comprises a first normally closed contact (KM11) connected in series with the first normally open button (SB1) and the first coil (KM14); The backward control sub-circuit further comprises a second normally closed contact (KM21) connected in series with the second normally open button (SB2) and the second coil (KM24); Wherein, the first normally closed contact (KM11) and the second normally closed contact (KM21) are interlocked.

3. The forward and backward control module according to claim 1, wherein: The forward control sub-circuit further comprises a first limit switch (SQ1) connected in series with the first normally open button (SB1) and the first coil (KM14); The backward control sub-circuit further comprises a second limit switch (SQ2) connected in series with the second normally open button (SB2) and the second coil (KM24).

4. The front and rear control module according to claim 1, wherein Further comprising a first fuse (FU1), the forward control sub-circuit and the backward control sub-circuit being connected in series with the first fuse (FU1) and used for connecting with the alternating current power supply.

5. The front and rear control module according to claim 1, wherein Further comprising a first air switch (QF1), one end of the first air switch (QF1) being connected with the other end of the frequency converter (VFD), the other end of the first air switch (QF1) being used for connecting with the alternating current power supply.

6. A control circuit, characterized by The forward and backward control module according to any one of claims 1-5, further comprising: A left and right control module used for connecting with the alternating current power supply; An up and down control module used for connecting with the alternating current power supply.

7. A control circuit according to claim 6, characterised in that, The up and down control module comprises: A third motor (M3), a first overload thermal relay (KJ1), a second overload thermal relay (KJ2), a third overload thermal relay (KJ3), a fifth contactor (KM5), a sixth contactor (KM6), the third motor (M3) is connected to the fifth contactor (KM5) through the first overload thermal relay (KJ1), the second overload thermal relay (KJ2) and the third overload thermal relay (KJ3), the fifth contactor (KM5) is used for being connected with the alternating current power supply, the third motor (M3) is also connected to the sixth contactor (KM6) through the first overload thermal relay (KJ1), the second overload thermal relay (KJ2) and the third overload thermal relay (KJ3), the sixth contactor (KM6) is used for being connected with the alternating current power supply; The upward control sub-circuit includes a fifth normally open button (SB5), a fifth normally closed contact (KM51), a fifth limit switch (SQ5) and a fifth coil (KM52) connected in series; The downward control sub-circuit includes a sixth normally open button (SB6), a sixth normally closed contact (KM61), a sixth limit switch (SQ6) and a sixth coil (KM62) connected in series; The normally closed contact (KJ11) of the first overload thermal relay (KJ1), the normally closed contact (KJ21) of the second overload thermal relay (KJ2) and the normally closed contact (KJ31) of the third overload thermal relay (KJ3) are connected in series, one end of which is connected to the upward control sub-circuit and the downward control sub-circuit which are connected in parallel with each other, and the other end is used for being connected with the alternating current power supply, the upward control sub-circuit and the downward control sub-circuit which are connected in parallel with each other are also used for being connected with the alternating current power supply, and the fifth normally closed contact (KM51) and the sixth normally closed contact (KM61) are interlocked.

8. A control circuit according to claim 7, characterised in that, The upward and downward control module further includes: A third fuse (FU3), the other end of the normally closed contact (KJ11) of the first overload thermal relay (KJ1), the normally closed contact (KJ21) of the second overload thermal relay (KJ2) and the normally closed contact (KJ31) of the third overload thermal relay (KJ3) connected in series is used for being connected with the alternating current power supply through the third fuse (FU3); A third air switch (QF3), one end of the third air switch (QF3) is connected with the fifth contactor (KM5) and the sixth contactor (KM6), and the other end of the third air switch (QF3) is used for being connected with the alternating current power supply.

9. A control circuit according to claim 6, wherein, The left and right control module includes: A second motor (M2), a second thermal relay (FR2), a third contactor (KM3) and a fourth contactor (KM4), one end of the third contactor (KM3) is connected through the second thermal relay (FR2) and the second motor (M2), the other end of the third contactor (KM3) is connected through a second air switch (QF2) for connecting with the AC power supply, one end of the fourth contactor (KM4) is connected through the second thermal relay (FR2) and the second motor (M2), the other end of the fourth contactor (KM4) is connected through the second air switch (QF2) for connecting with the AC power supply; The left control sub-circuit comprises a third normally open button (SB3), a third normally closed contact (KM31), a third limit switch (SQ3) and a third coil (KM32) connected in series; The right control sub-circuit comprises a fourth normally open button (SB4), a fourth normally closed contact (KM41), a fourth limit switch (SQ4) and a fourth coil (KM42) connected in series; Wherein, one end of the normally closed contact (FR21) of the second thermal relay (FR2) is connected with the left control sub-circuit and the right control sub-circuit in parallel, the other end of the normally closed contact (FR21) of the second thermal relay (FR2) is connected through a second fuse (FU2) for connecting with the AC power supply, the left control sub-circuit and the right control sub-circuit in parallel are also used for connecting with the AC power supply, the third normally closed contact (KM31) and the fourth normally closed contact (KM41) are interlocked.

10. A gantry crane, characterized in that A control circuit as claimed in any one of claims 6 to 9.

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