JP7672857B2 - Electromagnetic brake and transport cart equipped with electromagnetic brake - Google Patents

Description

The present invention relates to the structure of electromagnetic brakes for large transport vehicles, and more specifically to a technology that provides damage prevention functionality by devising an electromagnetic brake structure.

Some transport carts used to transport large structures are equipped with many wheels. Electromagnetic brakes are used as the parking brakes for such transport carts, and in the case of transport carts with many wheels, an appropriate number of electromagnetic brakes are provided. However, using many electromagnetic brakes creates the problem of increased effort required for inspection. The following technologies have been disclosed as methods for checking the normal operation of such electromagnetic brakes.

Patent Document 1 discloses technology related to electric disc brakes. When the brake pads thermally expand due to braking, the amount of thermal expansion of the brake pads is detected by comparing the temperature measured by the temperature sensor with a predetermined brake pad temperature-brake pad thermal expansion amount characteristic, and the position of the piston is moved backward by a length dimension equivalent to the amount of thermal expansion of the pads by operating the electric motor. This makes it possible to adjust the pad clearance of the electric disc brake.

Patent Document 2 discloses technology relating to a brake diagnostic system and a remote brake diagnostic device. The brake diagnostic system includes an acquisition unit, a calculation unit, and a judgment unit. In the operation section where the movable member moves when the electromagnetic brake is applied or released, the acquisition unit acquires a current waveform showing the change in the current flowing through the coil of the electromagnetic brake. The calculation unit calculates the degree of difference between the current waveform in the operation section when the electric brake is applied the Nth time and the current waveform in the operation section when the electromagnetic brake is applied the N-1 time, or between the current waveform in the operation section when the electromagnetic brake is released the N-1 time, and the current waveform in the operation section when the electromagnetic brake is released the N-1 time. The judgment unit determines the presence or absence of a stability problem in which the movement of the movable member randomly fluctuates based on the variance of the degree of difference for a predetermined number of times.

JP 2009-8241 A JP 2020-85112 A

However, when using the technology of Patent Document 1 on a transport cart, it is necessary to have a mechanism for detecting the thermal expansion rate of the brake pads in all of the numerous electromagnetic brakes and adjusting the position of the pistons. Also, when using the technology of Patent Document 2 on a transport cart, it is necessary to prepare an acquisition unit, a calculation unit, and a judgment unit, respectively, and it becomes necessary to store and analyze all of the information from the numerous electromagnetic brakes.

On the other hand, if the electromagnetic brake is to function as a parking brake when the transport cart is stopped, the electromagnetic brake must be released when the transport cart is moved. However, if the electromagnetic brake remains activated due to some trouble, the transport cart will move while dragging the brake. In particular, in the case of large transport carts, which are equipped with many electromagnetic brakes, even if some electromagnetic brakes remain activated due to a malfunction, the transport cart may move due to the driving force generated by the wheels with the electromagnetic brake released. This may lead to trouble such as the stop brake generating heat or burning out while remaining activated. However, it is not desirable in terms of cost and maintenance to install an electromagnetic brake equipped with a complex function such as that of Patent Document 1 or Patent Document 2 on such a transport cart.

Therefore, the present invention aims to solve these problems and provide an electromagnetic brake capable of detecting contact between the armature and the yoke, or a transport cart using an electromagnetic brake.

To achieve the above objective, an electromagnetic brake according to one aspect of the present invention has the following features:

(1) An electromagnetic brake including a yoke having a coil and an armature that contacts the yoke when the coil is energized,
The yoke or the armature chair is electrically divided into at least two parts, that is, a first yoke and a second yoke, or a first armature chair and a second armature chair,
When the armature contacts the yoke,
an electrical inspection circuit conducting from the first yoke through the armature to the second yoke;
Or, an electrical inspection circuit is completed that is conducted from the first armature chair to the second armature chair via the yoke.
It is characterized by:

The aspect described in (1) above makes it possible to check the contact between the yoke and the armature chair. This is because an electrical inspection circuit is formed by contact between the first yoke and the second yoke and the armature chair, or an inspection circuit is formed by contact between the first armature chair and the second armature chair and the yoke, and contact can be checked by conducting a continuity test. This makes it possible to determine whether the brake is working, whether the electromagnetic brake is a non-excitation actuated brake or an excitation actuated brake.

Therefore, with a simple structure, even if the transport cart tries to move with some of the brakes still applied due to a brake failure as described in the problem, it is possible to detect this in advance and prevent trouble. This effect can be achieved with a simple configuration in which the yoke is divided into a first yoke and a second yoke, the first yoke and the second yoke are insulated from each other, and an inspection circuit can be formed when the first yoke and the second yoke come into contact with the armature chair, or the armature chair is divided and an inspection circuit can be formed when it comes into contact with the yoke, making it possible to provide an electromagnetic brake that is relatively low cost and easy to maintain.

In order to achieve the above object, a transport cart according to another aspect of the present invention has the following features:

(2) A transport vehicle having a plurality of electromagnetic brakes, the electromagnetic brakes being used when the transport vehicle is stopped,
The electromagnetic brake,
a yoke or armature having a coil and electrically divided into at least two;
an armature that contacts the yoke when the coil is energized;
When the coil is energized and the armature contacts the yoke, an electrical inspection circuit is completed, thereby confirming the contact between the yoke and the armature;
It is characterized by:

By using the aspect described in (2) above, even if the electromagnetic brake mounted on the transport cart fails, it is possible to determine the failure and prevent trouble from occurring. For transport cars that use many electromagnetic brakes, it is desirable to be able to check the structure of the electromagnetic brakes with a simple structure, which has advantages in terms of both cost and maintenance.

(3) In the transport cart according to (2),
a check mechanism that energizes the inspection circuit when the vehicle is released from a stopped state, checks the operation of the electromagnetic brake, and then operates the inspection circuit;
is preferred.

The aspect described in (3) above makes it possible for the check mechanism to detect abnormalities before the transport cart moves, preventing brake drag as described in the problem section, and enabling safe operation of the transport cart. As shown in (2), the check mechanism has a simple configuration that can check contact between the yoke and the armature chair by passing electricity through it, so it is easy to check whether the transport cart is normal before moving it, and if an abnormality is found, it can be dealt with immediately. This check mechanism can also be used for periodic inspections, and since it can identify defective electromagnetic brakes, it is expected to make maintenance more efficient.

(4) In the transport cart according to (3),
the checking mechanism is provided with a measuring means for measuring a voltage value when a current is applied to the coil;
is preferred.

According to the aspect described in (4) above, the voltage value is measured and recorded each time the transport cart is maintained, making it possible to know the state of the electromagnetic brake. In order to attract the armature to the yoke, it is necessary to generate magnetic force by passing electricity through a coil attached to the yoke with the armature chair spaced a specified distance away. The magnetic force required at this time varies depending on the distance between the yoke and the armature chair. Therefore, if the distance between the coil and the armature chair increases, a higher voltage is applied to the coil before the yoke and the armature chair are attracted to each other. Therefore, by utilizing this effect and checking the voltage each time maintenance is performed, it is possible to estimate the approximate wear of the electromagnetic brake. Such a check can be performed without disassembling the electromagnetic brake, making it possible to check without the hassle of maintenance.

FIG. 2 is a schematic plan view of the transport platform vehicle according to the embodiment. FIG. 2 is a schematic diagram of a wheel unit according to the present embodiment. FIG. 2 is a plan view of the electromagnetic brake according to the embodiment. FIG. 2 is a side cross-sectional view of the electromagnetic brake according to the embodiment. FIG. 2 is a bottom view of the electromagnetic brake according to the embodiment. FIG. 2 is a cross-sectional view of the electromagnetic brake according to the embodiment. FIG. 4 is a schematic diagram showing a state in which the yoke and the armature chair are separated from each other in this embodiment. 5 is a schematic diagram showing a contact state between a yoke and an armature chair in the embodiment; FIG.

First, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic plan view of a transport cart 100 according to this embodiment. FIG. 2 shows a schematic diagram of a wheel unit 110. The transport cart 100 is equipped with a driver's seat 102 and a transport platform 103, and is supported by 32 tires 101. As shown in FIG. 1, the tires 101 are arranged in a set of four wheels to form a wheel unit 110, which is disposed at eight locations on the lower part of the transport cart 100. Each wheel unit 110 is equipped with an electromagnetic brake 120 and a motor 130. The number of wheel units 110 can be increased or decreased as necessary.

The wheel unit 110 can rotate the tires 101 and run the transport cart 100 by driving the motor 130, and can apply the brakes to prevent the tires 101 of the wheel unit 110 from rotating by activating the electromagnetic brake 120. Note that it is not necessary for the electromagnetic brake 120 and motor 130 to be connected to all wheel units 110, and there is no prohibition on using wheel units 110 that do not have the electromagnetic brake 120 or motor 130 as necessary. The motor 130 and electromagnetic brake 120 are connected to the control device 200 and power source 210, respectively.

Figure 3 shows a plan view of the electromagnetic brake 120. Figure 4 shows a side cross-sectional view of the electromagnetic brake 120. Figure 5 shows a bottom view of the electromagnetic brake 120. Figure 5 corresponds to the back side of Figure 3. The electromagnetic brake 120 employs a non-excitation brake system in which the brake is applied when not energized, and is used as a stopping brake when the transport cart 100 is stopped.

The stator side of the electromagnetic brake 120 is provided with a yoke 121 housed and held in a bracket 132. As shown in FIG. 3, the yoke 121 is made up of a first yoke 121a and a second yoke 121b, each of which has a half-donut shape. The bracket 132 is provided with a number of recesses each holding a spring 123. The yoke 121 holds a coil 122 in an insulated state, and the coil 122 acts as an electromagnet by receiving power from the outside through a lead wire 124, generating magnetic force.

The spring 123 provided on the bracket 132 has one end embedded and held in the bracket 132 as described above, and the other end abuts against the armature chair 125, acting to separate the armature chair 125 and the yoke 121. This creates a gap S between the yoke 121 and the armature chair 125, as shown in Figure 4. The gap S is set to about 0.1 to 0.2 mm.

The armature chair 125 is disk-shaped and has a structure in which the shaft 126 penetrates through it at three places. The shaft 126 is erected on the yoke 121 and supports the plate 128. Therefore, the armature chair 125 is guided by the shaft 126 and can move between the armature chair 125 and the plate 128. For this reason, it is preferable that the sleeve 126a used to ensure sliding between the shaft 126 and the armature chair 125 is made of a material with high self-lubricating properties.

A disk 127 is placed between the plate 128 and the armature chair 125. A hub 129 is held in mesh with the disk 127, and the drive shaft 135 shown in FIG. 6 can be fixed to the hub 129. The drive shaft 135 is structured to extend from the motor 130, and the disk 127 and hub 129 function as a rotor together. Therefore, when the armature chair 125 moves toward the plate 128 while no current is applied, the plate 128 and the armature chair 125 come into surface contact with each other, sandwiching the disk 127, and exerting a large braking force.

The first yoke 121a and the second yoke 121b are each provided with a contact confirmation lead wire 131, and the contact surfaces of the armature chair 125 and the yoke 121 (the first yoke 121a and the second yoke 121b) are not insulated. Therefore, an electric circuit is formed when the armature chair 125 and the yoke 121 come into contact with each other, and contact can be confirmed by passing electricity through the contact confirmation lead wire 131. The contact confirmation lead wire 131 is connected to the control device 200, and the control device 200 issues a command to confirm contact between the yoke 121 and the armature chair 125. If necessary, the operator of the transport cart 100 or the like is notified of the result.

Next, a description will be given of the operation of the electromagnetic brake 120. A cross-sectional view of the electromagnetic brake 110 is shown in Fig. 6, which corresponds to Fig. 4.
<Non-excitation state>
In a non-excited state where the coil 122 is not energized, the disk 127 is sandwiched between the plate 128 and the armature chair 125 as shown in Fig. 4. In other words, the armature chair 125 is biased by a spring 123 held by a bracket 132, thereby pressing the disk 127 against the plate 128. In this state, the disk 127 fixed to the end of the drive shaft 135 via a hub 129 cannot rotate, and therefore the drive shaft 135 cannot rotate, and the motor 130 connected to the drive shaft 135 cannot rotate either. As a result, the tire 101 is in a braked state.

<Excitation state>
On the other hand, in an excited state where the coil 122 is energized, the armature chair 125 is magnetically attracted to the coil 122 against the biasing force of the spring 123 as shown in Fig. 6. As a result, the armature chair 125 moves so as to come into contact with the stator 121, and the disk 127, which is released from the state where it is sandwiched between the armature chair 125 and the plate 128, becomes capable of rotating. Therefore, the drive shaft 135 fixed to the disk 127 via the hub 129 becomes rotatable, and the wheel unit 110 is driven by the rotation of the motor 130.

The electromagnetic brake 120 of this embodiment has the above configuration, and therefore provides the following actions and effects.

First, when a problem occurs in the electromagnetic brake 120 and the brake is not released, it is possible to detect the abnormality with a simple configuration. This is because, in the electromagnetic brake 120, which includes a yoke 121 equipped with a coil 122 and an armature chair 125 that contacts the yoke 121 when current is applied to the coil 122, the yoke 121 is electrically divided into at least two yokes, a first yoke 121a and a second yoke 121b, and when the armature chair 125 contacts the yoke 121, an electrical inspection circuit is completed that conducts from the first yoke 121a through the armature chair 125 to the second yoke 121b. As a result, it is possible to confirm that the armature chair 125 has contacted the yoke 121.

Figure 7 shows a schematic diagram of the yoke 121 and the armature chair 125 in a separated state. Figure 8 shows a schematic diagram of the yoke 121 and the armature chair 125 in a contact state. The first yoke 121a and the second yoke 121b are connected to a contact confirmation lead wire 131, but since the first yoke 121a and the second yoke 121b are insulated from each other, they are not conductive in the state shown in Figure 7, i.e., in the non-excited state. On the other hand, when the armature chair 125 is in contact with the first yoke 121a and the second yoke 121b as shown in Figure 8, the first yoke 121a and the second yoke 121b form an electric circuit via the armature chair 125.

This makes it possible to detect contact between the yoke 121 and the armature chair 125. This contact confirmation can be achieved by passing electricity through the contact confirmation lead wire 131, so abnormality detection can be achieved with a simple configuration in which the yoke 121 is divided into a first yoke 121a and a second yoke 121b, and the first yoke 121a and the second yoke 121b are insulated and held in place. As described in the problem section, when multiple electromagnetic brakes 120 are used on the transport cart 100, a simpler structure has great advantages in terms of both cost and maintenance.

When such an electromagnetic brake 120 is used as a braking device for stopping the transport cart 100, it is sufficient to confirm that the armature chair 125 is separated from the yoke 121, and there is no need for a complex structure or control as shown in Patent Document 1 or Patent Document 2. Therefore, even if multiple electromagnetic brakes 120 are used, costs do not increase, and there is no need to make the electromagnetic brakes 120 structurally large, so it is possible to respond at low cost even when modifying an existing transport cart 100.

In the case of a transport cart 100 using multiple electromagnetic brakes 120, if one of them breaks down, it is possible to determine the malfunction by detecting whether the yoke 121 of the electromagnetic brake 120 is in contact with the armature chair 125. As a result, if it is possible to detect a situation in which one of the wheel units 110 is unintentionally applying the brakes and notify the operator of the malfunction, it is possible to prevent the transport cart 100 from being driven without knowing that the brakes are applied.

The transport cart 100 of this embodiment is used to move heavy objects weighing tens to hundreds of tons, so the drive motor 130 also generates a large force. For this reason, there are cases where the cart continues to run even when some of the electromagnetic brakes 120 are malfunctioning and braking is applied, which can result in problems such as the motor 130 and electromagnetic brakes 120 overheating or burning out, but the present invention makes it possible to prevent such problems.

In addition, the thickness of the disk 127 of the electromagnetic brake 120 changes as it wears away due to friction, and the gap S increases with the change in thickness of the disk 127. In such a case, there may be a problem where the magnetic force of the coil 122 is unable to attract the armature chair 125, and if the armature chair 125 cannot be attracted to the yoke 121, the electromagnetic brake 120 may not be released. If the magnetic force generated by the coil 122 is strong, it is possible to attract the armature chair 125 even if the gap S becomes large, but to do this, it is necessary to increase the voltage applied to the coil or the coil itself.

Therefore, by utilizing this characteristic, a voltmeter corresponding to each electromagnetic brake 120 is prepared, and the voltage value applied to the coil 122 when it is detected that the armature chair 125 has been electrically attracted to the yoke 121 is measured, and the minimum strength of the magnetic force required to attract the armature chair 125 is determined in advance and set as a threshold value, it becomes possible to predict the amount of wear on the disk by checking the voltage value applied to the coil 122 in addition to confirming the adhesion during maintenance. This type of check can be performed without disassembling the electromagnetic brake 120, and it becomes possible to grasp the amount of wear on the disk 127 during maintenance, making it possible to greatly improve maintainability.

The above describes the electromagnetic brake 120 according to the present invention, but the present invention is not limited to this, and various modifications are possible without departing from the spirit of the invention. For example, in this embodiment, multiple electromagnetic brakes 120 are used to function as brakes when the transport cart 100 is stopped, but this does not prevent the electromagnetic brake 120 from being used for anything other than the transport cart 100. Also, although shown as an electromagnetic brake 120, this does not prevent the present invention from being applied to an electromagnetic clutch having a similar structure.

In addition, although the electromagnetic brake 120 of the present invention employs a non-excitation brake type, it is also possible to apply it to an excitation brake type. The configuration of the electromagnetic brake 120 may also be modified as appropriate. For example, the spring 123 is a coil spring type, but it may be changed to a leaf spring or the like instead. In addition, although the yoke 121 has been described as being electrically divided into two and equipped with a first yoke 121a and a second yoke 121b, the armature chair 125 may also be electrically divided into two to complete the inspection circuit. In this case, a lead wire equivalent to the contact confirmation lead wire 131 is connected to the armature chair 125 side.

120: Electromagnetic brake 121: Yoke 121a: First yoke 121b: Second yoke 122: Coil

Claims (4)

An electromagnetic brake including a yoke having a coil and an armature that contacts the yoke when the coil is energized,
The armature chair is electrically divided into at least two armature chairs, a first armature chair and a second armature chair,
When the armature chair contacts the yoke, an electrical test circuit is completed that is conductive from the first armature chair to the second armature chair via the yoke;
An electromagnetic brake characterized by: A transport vehicle having a plurality of wheel units and an electromagnetic brake for each wheel unit, the electromagnetic brake being used when the transport vehicle is stopped,
The electromagnetic brake is
a first yoke and a second yoke electrically divided into at least two parts, insulated from each other and provided with a contact confirmation lead wire;
a coil held in an insulated state by the first yoke and the second yoke;
an armature that contacts the first yoke and the second yoke when the coil is energized;
When the coil is energized and the armature comes into contact with the first yoke and the second yoke, an electrical inspection circuit is completed, and the contact between the first yoke and the second yoke and the armature is confirmed by energizing the contact confirmation lead wire .
A transport cart characterized by the above. The transport vehicle according to claim 2,
a check mechanism that energizes the inspection circuit when the vehicle is released from a stopped state, checks the operation of the electromagnetic brake, and then operates the inspection circuit;
A transport cart characterized by the above. The transport vehicle according to claim 3,
the checking mechanism is provided with a measuring means for measuring a voltage value when a current is applied to the coil;
A transport cart characterized by the above.

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