A single-phase asynchronous motor drive for a crane

Abstract

The utility model relates to motor technical field more specifically, and relates to a single -phase asynchronous motor drive device for crane. Comprise motor body, external power -off brake assembly, capacitor module and control switch module constitute. Motor body contains first work winding and second work winding, respectively adapts heavy load hoist and no -load descending working condition. The function of control switch module is to connect two kinds of circuits: when hoisting, first capacitor and second work winding are connected in series, and then are connected in parallel with first work winding, when descending, second capacitor and first work winding are connected in series, and then are connected in parallel with second work winding, realize the optimal matching of working condition and electrical characteristic. At the same time, when connecting any work loop, control module synchronously energizes power -off brake coil, removes the brake, and guarantees smooth operation. The device is stable in braking performance, convenient to control, safe and reliable. The utility model mainly applies to single -phase asynchronous motor drive aspect of crane.

Description

Technical Field

[0001] This utility model relates to the field of electric motor technology, and more specifically, to a single-phase asynchronous motor drive device for cranes. Background Technology

[0002] In the field of small lifting machinery, capacitor-run single-phase asynchronous motors are widely used due to their convenience of direct connection to a single-phase power grid. However, existing motors of this type have the following two main technical drawbacks when applied to lifting operations: First, the electromagnetic design of the motor fails to optimize for lifting conditions. In existing technology, the forward winding (corresponding to heavy-load lifting) and the reverse winding (corresponding to no-load or light-load lowering) of the motor typically use the same wire diameter, number of turns, and other parameters, and are configured with the same capacity operating capacitor. This results in the motor generating similar operating current and temperature rise during no-load or light-load lowering operation as it does during heavy-load lifting. This not only causes unnecessary energy loss and heat generation, accelerates the aging of the motor insulation and shortens its service life, but also prevents the material potential of the motor core and windings from being fully utilized according to actual load requirements, resulting in resource waste.

[0003] Secondly, the integration method of the brake poses safety and performance risks. To meet the power-off braking function required by crane mechanisms, existing motors generally integrate the power-off brake into the motor housing. This brake relies on the electromagnetic force generated by the energization of the stator windings to overcome the spring pressure to release the brake, and then brakes under the action of the spring after power is cut off. During motor operation, the heat generated by this structure is directly conducted to the built-in brake friction pads and related components, causing the temperature of the friction pair to rise, its friction coefficient to decrease, and the braking torque to decay, seriously threatening the safety and reliability of lifting operations. Furthermore, to achieve magnetic circuit conduction between the braking surfaces, a section of electrical pure iron that does not generate residual magnetism must be added to the rear end of the rotor. This non-magnetic material occupies the space that could be used for magnetically conductive silicon steel sheets, which is equivalent to shortening the effective length of the stator and rotor cores, directly limiting the improvement of motor power density. Utility Model Content

[0004] To overcome the shortcomings of the existing technology, this utility model provides a single-phase asynchronous motor drive device for cranes. This device fully utilizes the characteristic that crane motors do not require large torque output during reverse rotation, providing a device with high forward power, low current during no-load descent in reverse, stable braking performance, and convenient, safe, and reliable operation.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A single-phase asynchronous motor drive device for a crane includes a motor body, the motor body comprising a front cover, a stator housing, a stator core fixed inside the stator housing, stator windings disposed on the stator core, a rotor rotatably disposed within the stator core cavity via a shaft, and a rear cover fixedly mounted on one end of the stator housing. The front cover is fixedly mounted on the other end of the stator housing. The stator windings include a first working winding and a second working winding with different parameters; the first working winding is used for heavy-load lifting conditions, and the second working winding is used for no-load or light-load lowering conditions. A power failure brake assembly is fixedly installed on the outer end of the rear cover of the motor and is connected to the shaft end of the rotor for transmission. A capacitor module, comprising a first capacitor and a second capacitor with different capacitance values; A control switch module is used to selectively connect a first circuit structure and a second circuit structure; the first circuit structure is a lifting circuit, in which the first capacitor is connected in series with the second working winding and then in parallel with the first working winding; the second circuit structure is a descent circuit, in which the second capacitor is connected in series with the first working winding and then in parallel with the second working winding. The control switch module is also provided with a brake control circuit, which is used to simultaneously energize the power failure brake coil of the power failure brake assembly when the lifting circuit or the lowering circuit is connected.

[0006] The control switch module includes a lifting switch unit and a lowering switch unit. The lifting switch unit includes a first lifting contact, a second lifting contact, and a third lifting contact. The lowering switch unit includes a first lowering contact, a second lowering contact, and a third lowering contact. The connection relationship constituting the lifting circuit is as follows: the power supply live wire passes through the first lifting contact, and a first path is connected to one end of the first working winding; the second path passes through the first capacitor and the second lifting contact to one end of the second working winding. The connection relationship constituting the lowering circuit is as follows: the power supply live wire passes through the first lowering contact, and a first path is connected to one end of the second working winding; the second path passes through the second capacitor and the second lowering contact to one end of the first working winding. The common terminal of the first working winding and the second working winding is connected to the power supply neutral line. The connection relationship of the brake control circuit is as follows: one end of the power-off brake coil is connected to the power supply, and the other end is connected to the power supply neutral line via the parallel-connected third lifting contact and the third lowering contact.

[0007] The control switch module also includes a force booster switch. The branch formed by the force booster switch and the second capacitor in series is connected in parallel with the branch formed by the first capacitor and the second lifting contact in series, so that when the force booster switch is closed under lifting conditions, the first capacitor and the second capacitor operate in parallel.

[0008] The lifting switch unit, the lowering switch unit, and the force booster switch are integrated into a portable operator; the operating components of the lifting switch unit and the lowering switch unit are connected by a mechanical interlock structure.

[0009] The rotor is made of stacked silicon steel sheets at one end near the power failure brake assembly, and the length of the stator and rotor cores increases as the power failure brake assembly is externally mounted.

[0010] It also includes a thermal protection switch, which is connected in series in the lifting circuit and installed inside the motor cavity.

[0011] It also includes a junction box, in which both the first capacitor and the second capacitor are installed in the internal cavity of the junction box.

[0012] The cross-sectional area of ​​the conductor of the first working winding in the stator is greater than that of the conductor of the second working winding, and the number of turns of the first working winding is less than the number of turns of the second working winding.

[0013] The motor body includes a front cover, which is fixed to the stator housing at the end away from the rear cover and together with the rear cover supports the rotating shaft.

[0014] It also includes a fan cover, which is fixedly installed on the outer contour of the motor rear cover and outside the power failure brake assembly.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: This design achieves high power and torque during forward lifting and low current and heat generation during reverse descent. It improves the power-to-weight ratio of the motor during forward lifting, enhances the motor's performance requirements, and conserves overall resources. Furthermore, during forward lifting, the forward capacitor C1 and the reverse capacitor C2 can be connected in parallel to achieve short-term high power. For example, in cases of low voltage, pressing the lifting switch unit while simultaneously activating the booster switch for the parallel reverse capacitor C2 increases the input current, thus providing additional force.

[0016] The power-off brake assembly is located at the outer end of the motor's rear cover, overcoming the deficiency of reduced braking force caused by the motor's heat generation, which leads to overheating of the friction plates and the motor's rear cover, thus ensuring safe operation. A thermal protection switch is installed in the crane's forward rotation control circuit. When the crane is overloaded, the forward rotation circuit is cut off by overheat protection. At this time, the reversing button can be pressed to reconnect the circuit and lower the load. The reversing capacitor has a smaller value, resulting in less current and reduced heat generation. This prevents the motor from overheating and burning out, while also ensuring operational safety.

[0017] The lifting switch unit, lowering switch unit, and booster switch are housed in the same handle switch housing, which facilitates operation. At the same time, the lifting switch unit and lowering switch unit are mechanically interlocked, meaning they cannot be pressed simultaneously, ensuring safety.

[0018] The junction box is designed to accommodate both forward and reverse capacitors, simplifying the wiring layout and reducing the wiring failure rate. Attached Figure Description

[0019] Figure 1 A schematic diagram of the electric motor structure of this utility model; Figure 2 Electrical schematic diagram of this utility model; Figure 3 Electrical schematic diagram of the forward rotation of this utility model; Figure 4 The electrical schematic diagram of this utility model is reversed; Figure 5 Electrical schematic diagram of the parallel reverse capacitor for forward rotation of this utility model; Figure 6 Schematic diagram of the control switch module of this utility model; In the diagram: 1 is the front cover of the motor, 2 is the stator housing, 3 is the stator winding, 4 is the stator core, 5 is the rotor, 6 is the rear cover of the motor, 7 is the power failure brake assembly, 8 is the motor fan cover, L is the live wire, N is the neutral wire, E is the ground wire, ZAQ is the lifting switch unit, ZAQ1 is the first lifting contact, ZAQ2 is the second lifting contact, ZAQ3 is the third lifting contact, FAQ is the lowering switch unit, FAQ1 is the first lowering contact, FAQ2 is the second lowering contact, FAQ3 is the third lowering contact, C1 is the first capacitor, C2 is the second capacitor, AQ is the force boosting switch, θ is the thermal protection switch, U is the first working winding, W is the second working winding, and YA is the power failure brake coil. Detailed Implementation

[0020] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0022] like Figures 1 to 6 As shown, a single-phase asynchronous motor drive device for a crane includes a motor body, which includes a front cover 1, a stator housing 2, a stator core 4 fixed inside the stator housing 2, a stator winding 3 disposed on the stator core 4, a rotor 5 rotatably disposed in the inner cavity of the stator core 4 via a rotating shaft, and a rear cover 6 fixedly installed at one end of the stator housing 2. The front cover 1 is fixedly installed at the other end of the stator housing 2. The stator winding 3 includes a first working winding U and a second working winding W with different parameters; the first working winding U is used for heavy-load lifting conditions, and the second working winding W is used for no-load or light-load lowering conditions. The power failure brake assembly 7 is fixedly installed on the outer end of the motor rear cover 6 and is connected to the shaft end of the rotor 5 for transmission. The capacitor module includes a first capacitor C1 and a second capacitor C2 with different capacitance values. The control switch module is used to selectively connect the first circuit structure and the second circuit structure. The first circuit structure is a lifting circuit, in which the first capacitor C1 is connected in series with the second working winding W and then in parallel with the first working winding U. The second circuit structure is a descent circuit, in which the second capacitor C2 is connected in series with the first working winding U and then in parallel with the second working winding W. The control switch module is also equipped with a brake control circuit, which is used to simultaneously energize the power failure brake coil YA of the power failure brake assembly 7 when the lifting circuit or the lowering circuit is connected.

[0023] The control switch module includes a lifting switch unit ZAQ and a lowering switch unit FAC. The lifting switch unit ZAQ includes a first lifting contact ZAQ1, a second lifting contact ZAQ2, and a third lifting contact ZAQ3; the lowering switch unit FAC includes a first lowering contact FAC1, a second lowering contact FAC2, and a third lowering contact FAC3. The connection relationship constituting the lifting circuit is as follows: the power supply live wire L, after passing through the first lifting contact ZAQ1, is first connected to one end of the first working winding U; the second path sequentially passes through the first capacitor C1 and the second lifting contact ZAQ2, and is connected to the first working winding U. One end of the two working windings W; the connection relationship forming the descent circuit is as follows: the power supply live wire L is connected to one end of the second working winding W via the first descent contact FAC1, and the second path is connected to one end of the first working winding U via the second capacitor C2 and the second descent contact FAC2; the common end of the first working winding U and the second working winding W is connected to the power supply neutral line N; the connection relationship of the brake control circuit is as follows: one end of the power failure brake coil YA is connected to the power supply, and the other end is connected to the power supply neutral line N via the parallel lifting third contact ZAQ3 and the descent third contact FAC3.

[0024] The control switch module also includes a force booster switch AQ. The branch formed by the force booster switch AQ and the second capacitor C2 in series is connected in parallel with the branch formed by the first capacitor C1 and the second lifting contact ZAQ2 in series. This ensures that when the force booster switch AQ is closed under lifting conditions, the first capacitor C1 and the second capacitor C2 operate in parallel.

[0025] The lifting switch unit ZAQ, the lowering switch unit FAQ, and the force booster switch AQ are integrated into a portable operator; the operating components of the lifting switch unit ZAQ and the lowering switch unit FAQ are connected by a mechanical interlock structure.

[0026] The end of rotor 5 near the power failure brake assembly 7 is made of stacked silicon steel sheets, and the length of the stator and rotor cores of rotor 5 increases as the power failure brake assembly 7 is externally mounted.

[0027] It also includes a thermal protection switch θ, which is connected in series in the lifting circuit and installed inside the motor cavity.

[0028] It also includes a junction box, in which the first capacitor C1 and the second capacitor C2 are both installed in the internal cavity of the junction box.

[0029] The cross-sectional area of ​​the conductor in the first working winding U in the stator is greater than the cross-sectional area of ​​the conductor in the second working winding W, and the number of turns in the first working winding U is less than the number of turns in the second working winding W.

[0030] The motor body includes a front cover 1, which is fixed to the stator housing 2 at the end away from the rear cover 6, and together with the rear cover 6, supports the rotating shaft.

[0031] It also includes a fan cover 8, which is fixedly installed on the outer contour of the motor rear cover 6 and the outside of the power failure brake assembly 7.

[0032] Before the device is powered on or when it is stopped, all lifting switch units ZAQ, lowering switch units FACQ, and force boosting switches AQ are in the open state. No current flows through the lifting circuit, lowering circuit, and brake control circuit. The de-energized brake coil YA is de-energized, and the motor is reliably locked.

[0033] Start-up operation: The user presses the lifting switch unit ZAQ or the lowering switch unit FAC. The two are mechanically interlocked to ensure that they cannot be turned on at the same time, thus ensuring safety.

[0034] Main Circuit: Pressing the lifting switch unit ZAQ closes the first lifting contact ZAQ1 and the second lifting contact ZAQ2, connecting the lifting circuit and forming a circuit structure where "the first capacitor C1 is connected in series with the second working winding W, and then in parallel with the first working winding U," causing the motor to rotate forward and output high torque. Pressing the lowering switch unit FAC closes its first lowering contact FAC1 and the second lowering contact FAC2, connecting the lowering circuit and forming a circuit structure where "the second capacitor C2 is connected in series with the first working winding U, and then in parallel with the second working winding W," causing the motor to reverse and significantly reducing current and heat generation. Simultaneously, the corresponding third lifting contact ZAQ3 or the third lowering contact FAC3 closes, energizing the de-energized brake coil YA, immediately releasing the brake, and the motor rotor begins to rotate.

[0035] While holding down the lifting switch unit ZAQ, the user also presses the booster switch AQ. At this time, the second capacitor C2 is connected to the circuit through the booster switch AQ, operating in parallel with the first capacitor C1, thus increasing the total capacitance of the circuit. The motor obtains short-term high power and torque output to cope with scenarios requiring additional power, such as heavy-load starting or low voltage. Taking a 1.35 kW two-pole crane capacitor-driven single-phase asynchronous motor as an example, the forward rotation power is increased by 4.4%, the reverse rotation energy saving is 43%, and the power is increased by 22% when the parallel reverse capacitor is connected during forward rotation. By moving the power-off brake out of the motor, the freed-up space can be used to increase the length of the stator and rotor and the windings, which can further increase the motor power by 10%.

[0036] If the motor overheats due to overload during lifting, the thermal protection switch θ, connected in series in the lifting circuit, will activate, cutting off the lifting circuit and brake control circuit. The motor will stop and brake immediately. Since the thermal protection switch θ is not connected in series in the descent circuit, the operator can press the descent switch unit FAQ at this time. The descent circuit and brake control circuit are then connected separately, allowing the device to safely lower the load to the ground in a low-current, low-heat descent mode, greatly improving operational safety.

[0037] Under any operating condition, releasing the currently pressed button resets all contacts, simultaneously cutting off the main circuit and the brake control circuit. The motor is de-energized, and the de-energized brake coil YA is de-energized, causing the device to stop operating quickly and reliably.

[0038] The above description only details the preferred embodiments of the present utility model. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model, and all such changes should be included within the protection scope of the present utility model.

Claims

1. A single-phase asynchronous motor drive device for cranes, characterized in that: The motor body includes a front cover (1), a stator housing (2), a stator core (4) fixed inside the stator housing (2), a stator winding (3) disposed on the stator core (4), a rotor (5) rotatably disposed in the cavity of the stator core (4) via a rotating shaft, and a rear cover (6) fixedly installed at one end of the stator housing (2). The front cover (1) is fixedly installed at the other end of the stator housing (2). The stator winding (3) includes a first working winding (U) and a second working winding (W) with different parameters. The first working winding (U) is used for heavy-load lifting conditions, and the second working winding (W) is used for no-load or light-load lowering conditions. The power failure brake assembly (7) is fixedly installed on the outer end of the motor rear cover (6) and is connected to the shaft end of the rotor (5) for transmission. A capacitor module, comprising a first capacitor (C1) and a second capacitor (C2) with different capacitance values. A control switch module is used to selectively connect a first circuit structure and a second circuit structure; the first circuit structure is a lifting circuit, in which the first capacitor (C1) is connected in series with the second working winding (W) and then in parallel with the first working winding (U); the second circuit structure is a descent circuit, in which the second capacitor (C2) is connected in series with the first working winding (U) and then in parallel with the second working winding (W). The control switch module is also provided with a brake control circuit, which is used to simultaneously energize the power failure brake coil (YA) of the power failure brake assembly (7) when the lifting circuit or the lowering circuit is connected.

2. A single-phase asynchronous motor drive device for a crane according to claim 1, characterized in that: The control switch module includes a lifting switch unit (ZAQ) and a lowering switch unit (FAQ). The lifting switch unit (ZAQ) includes a lifting first contact (ZAQ1), a lifting second contact (ZAQ2), and a lifting third contact (ZAQ3); the lowering switch unit (FAQ) includes a lowering first contact (FAQ1), a lowering second contact (FAQ2), and a lowering third contact (FAQ3). The connection relationship constituting the lifting circuit is as follows: the power supply live wire (L) passes through the lifting first contact (ZAQ1), and the first path is connected to one end of the first working winding (U). The second path passes through the first capacitor (C1) and the lifting second contact (ZAQ2) sequentially to the second... One end of the working winding (W); the connection relationship constituting the descent circuit is as follows: the power supply live wire (L) is connected to one end of the second working winding (W) via the first descent contact (FAQ1), and the second path is connected to one end of the first working winding (U) via the second capacitor (C2) and the second descent contact (FAQ2); the common terminal of the first working winding (U) and the second working winding (W) is connected to the power supply neutral wire (N); the connection relationship of the brake control circuit is as follows: one end of the power failure brake coil (YA) is connected to the power supply, and the other end is connected to the power supply neutral wire (N) via the parallel lifting third contact (ZAQ3) and the descent third contact (FAQ3).

3. A single-phase asynchronous motor drive device for a crane according to claim 2, characterized in that: The control switch module also includes a force booster switch (AQ). The branch formed by the force booster switch (AQ) and the second capacitor (C2) in series is connected in parallel with the branch formed by the first capacitor (C1) and the second lifting contact (ZAQ2) in series, so that when the force booster switch (AQ) is closed under lifting conditions, the first capacitor (C1) and the second capacitor (C2) operate in parallel.

4. A single-phase asynchronous motor drive device for a crane according to claim 3, characterized in that: The lifting switch unit (ZAQ), the lowering switch unit (FAQ), and the force booster switch (AQ) are integrated into a portable operator; the operating components of the lifting switch unit (ZAQ) and the operating components of the lowering switch unit (FAQ) are connected by a mechanical interlock structure.

5. A single-phase asynchronous motor drive device for a crane according to claim 1, characterized in that: The rotor (5) is made of stacked silicon steel sheets at one end near the power failure brake assembly (7), and the length of the stator and rotor (5) core increases as the power failure brake assembly (7) is external.

6. A single-phase asynchronous motor drive device for a crane according to claim 1, characterized in that: It also includes a thermal protection switch (θ), which is connected in series in the lifting circuit and is located inside the motor cavity.

7. A single-phase asynchronous motor drive device for a crane according to claim 1, characterized in that: It also includes a junction box, in which the first capacitor (C1) and the second capacitor (C2) are both installed in the internal cavity of the junction box.

8. A single-phase asynchronous motor drive device for a crane according to claim 1, characterized in that: The cross-sectional area of ​​the conductor of the first working winding (U) in the stator is greater than that of the conductor of the second working winding (W), and the number of turns of the first working winding (U) is less than the number of turns of the second working winding (W).

9. A single-phase asynchronous motor drive device for a crane according to claim 1, characterized in that: The motor body includes a front cover (1), which is fixed to the stator housing (2) at one end away from the rear cover (6) of the motor, and together with the rear cover (6), supports the rotating shaft.

10. A single-phase asynchronous motor drive device for a crane according to claim 9, characterized in that: It also includes a fan cover (8), which is fixedly installed on the outer contour of the motor rear cover (6) and outside the power failure brake assembly (7).

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