JPH10313504A - Controller in eddy current brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for preventing an abrupt change in braking force in an eddy current brake. SOLUTION: In a controller, vehicle speed is detected by a vehicle speed sensor 11 so as to detect revolutions of a rotating drum 47. When the detected vehicle speed is down below a given speed, the quantity in continuity to eddy current generating coils 51a to 58a is reduced according to the detected vehicle speed by a controller 13. Then, the braking force of an eddy current retarder 40 is continuously reduced according to the detected vehicle speed, thereby preventing an abrupt release state of brake of the eddy current retarder 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an eddy current brake which is an electromagnetic braking means used for, for example, braking of a vehicle and also referred to as an eddy current retarder.

[0002]

2. Description of the Related Art Eddy current brakes (eddy current retarders) are well known in the prior art, and are widely used especially for large vehicles such as trucks. This eddy current retarder is used, for example, when traveling down a long downhill, and reduces the frequency of use of a service brake (a brake operated by depressing a brake pedal by a driver) to reduce a driver's brake operation burden. In addition, effects such as suppression of service brake lining and pad wear and improvement of service life can be obtained.

An eddy current retarder is provided in a power transmission path from a transmission to an axle shaft, and includes a fixed portion fixedly held on a vehicle body and a rotating portion that rotates together with an output shaft, a propeller shaft, and the like. I have.

[0004] A plurality of electromagnets, each of which includes a core member made of iron or the like and an eddy current generating coil (electromagnetic coil) wound around the core member, are radially arranged on the fixed portion. The rotating unit has a rotating drum (rotating body) formed in a bottomed cylindrical shape, and the tubular portion of the rotating drum covers the electromagnet and rotates with the output shaft and the like. Then, during operation of the vehicle, the driver operates the operation switch to energize the eddy current generating coil, thereby braking the vehicle.

[0005] An example of the eddy current retarder configured as described above is disclosed in Japanese Patent Application Laid-Open No. 3-239199. In this eddy current retarder, by controlling the energizing period (current ON / OFF ratio) to the eddy current generating coil in accordance with the change in running conditions, current control of the eddy current generating coil is performed, and smooth braking is performed. The characteristics were to be obtained.

[0006]

However, in the above-mentioned eddy current retarder, when the vehicle speed of the vehicle becomes low (when the rotation speed of the rotary drum falls below a predetermined rotation speed), the power supply period is reduced. Was stopped, and the vehicle was not braked by the eddy current retarder. For this reason, the braking force of the vehicle is lost at the same time as the control of the power supply period is stopped, and it is necessary for the driver to suddenly perform the braking by the service brake, which causes a feeling of strangeness during driving.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a control device for an eddy current brake which prevents a sudden change in a braking force in the eddy current brake.

[0008]

In order to achieve such an object, a control device for an eddy current brake according to the present invention comprises:
The number of revolutions of the rotating body is detected by the number of revolutions detecting means. When the number of revolutions of the rotating body detected by the number of revolutions detecting means becomes equal to or less than a predetermined number of revolutions, the energization limiting means according to the detected number of revolutions. Control is performed to reduce the amount of power to the eddy current generating coil of the electromagnet.

According to the control device for an eddy current brake configured as described above, the amount of current (current value) supplied to the eddy current generating coil.
, The braking force of the eddy current brake changes. For this reason, when the rotational speed of the rotating body becomes equal to or less than the predetermined rotational speed, if the control for reducing the amount of current to the eddy current generating coil is performed in accordance with the detected rotational speed, the eddy current brake is continuously operated. Can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, the eddy current brake is provided in a power transmission path of a vehicle (for example, a power transmission path from a transmission to an axle shaft).
The so-called eddy current retarder is configured as shown in FIGS. 1 and 2. Therefore, the rotating drum 47 in the eddy current retarder 40 constitutes a “rotating body” described in the claims. This vehicle is also provided with a foot brake (service brake) that is operated by the driver stepping on the foot.

The operation of the eddy current retarder 40 is controlled by the controller 13. The controller 13 causes the detection signal from the vehicle speed sensor 11 for detecting the running speed of the vehicle to detect the rotation speed of the rotary drum 47, and sets the eddy current retarder 40 to an operation state (braking state) or an operation stop state. Retarder operation switch 12 for switching whether or not
The controller 13 controls the operation of the eddy current retarder 40 based on each input signal.

The eddy current retarder 40 is disposed on the output shaft of the transmission or on a propeller shaft connected thereto,
The drive transmitted through this is braked. The eddy current retarder 40 includes a fixed housing 41 fixedly held to the vehicle body 70, a bracket 42 coupled thereto, a fixed portion including a plurality of electromagnets 51 to 58 attached to the bracket 42, and a fixed housing 41. Bearing 44
a shaft 4 rotatably held via a and 44b
5. Flange couplings 46a, 46b, flange couplings 46a connected to both ends of the shaft 45
And a rotating unit composed of a rotating drum 47 and the like coupled to the rotary shaft.

The bracket 42 constituting the fixed portion has a cylindrical portion, and a plurality of electromagnets are mounted on the outer peripheral surface of the cylindrical portion at substantially equal intervals in a radial manner. The number of the electromagnets is several to several tens according to the required braking force. In the eddy current retarder 40, eight electromagnets 51 to 58 are mounted by bolts 51c to 58c. . Each of the electromagnets 51 to 58 includes a core member 51b to 58b made of a ferromagnetic material such as iron, and eddy current generating coils 51a to 58a wound around the core members 51b to 58b.

On the other hand, flange couplings 46a and 46b are connected to both ends of a shaft 45 constituting a rotating portion coaxially with the shaft 45 by a spline.
7 is bolted to the flange coupling 46a. The cylindrical portion of the rotating drum 47 is
1 to 58, and in this state, the core members 51b to 5b
The outer peripheral end surface of 8b is located close to and opposed to the inner peripheral surface of the rotating drum 47. A plurality of radiating fins 47a are formed on the outer periphery of the cylindrical portion of the rotary drum 47, and a plurality of radiating fins 47a are formed through the center of the cylindrical portion in a radial direction so as to discharge hot air therein. A hole 47b is formed.

In the eddy current retarder 40 having the above structure, the flange couplings 46a and 46b are connected to the transmission output shaft or a propeller shaft connected thereto.
The rotating part rotates together with the output shaft and the propeller shaft. In this state, when the eddy current generating coils 51a-58a of the electromagnets 51-58 are energized, the core members 51b-5
A magnetic flux is generated in the axial direction (radial direction of the eddy current retarder) in 8b, and this magnetic flux flows in the extension direction and crosses the cylindrical portion of the rotating drum 47. For this reason, the rotating drum 47
An eddy current is generated in the cylindrical portion of the rotary drum 47, and a braking torque opposite to the rotation direction of the rotary drum 47 is generated by the action of the eddy current, whereby the rotation is braked.

Here, in the eddy current retarder 40,
Operation control is performed according to the vehicle speed. As described above, the operation control of the eddy current retarder 40 is performed by the controller 13, and when the eddy current retarder 40 is in the operating state by the retarder operation switch 12, the controller 13 performs control based on the input signal from the vehicle speed sensor 11. As shown in FIG. 3, when the vehicle speed V detected by the vehicle speed sensor 11 falls below the predetermined speed V1, the eddy current generating coil 51a
The control to reduce the amount of current (current) to 58a is performed.

That is, when the vehicle speed V detected by the vehicle speed sensor 11 is higher than a predetermined speed V1, the current to each of the coils 51a to 58a is supplied at a current value of 100% without any limitation. You. When the vehicle speed V detected by the vehicle speed sensor 11 becomes equal to or lower than the predetermined speed V1, the controller 13 controls the energization time to the eddy current generating coils 51a to 58a by a duty ratio control at a control rate corresponding to the vehicle speed V. I do. As a result, the current value becomes 0
It can be controlled between 100%.

Therefore, the duty ratio control by the controller 13 is performed from the time when the vehicle speed V becomes lower than V1, and the energization time is shortened so that the current value becomes smaller as the vehicle speed V becomes slower, thereby controlling the eddy current retarder 40. Reduce the power gradually. When the vehicle speed V becomes 0 (when the vehicle stops), the eddy current generating coil 5
The power supply to 1a to 58a is cut off, and the operation of the eddy current retarder 40 is stopped.

Here, the eddy current generating coils 51a to 58a
The control for reducing the amount of power to the power supply is not limited to the duty ratio control (control of the power supply time) as described above, and the current value may be directly controlled. Further, while only one requirement such as the energization time and current may be controlled, a plurality of requirements may be controlled together.

In the above eddy current retarder 40, the vehicle speed V of the vehicle is detected in order to detect the number of revolutions of the rotating body (the rotating drum 47). However, the present invention is not limited to this. Instead, the rotational speed of the rotary drum 47 may be directly detected.

In the eddy current retarder 40, the temperatures of the rotating drum 47 and the coils 51a to 58a are detected. If these temperatures are higher than a predetermined temperature, the eddy current generating coil It may be configured to perform control to reduce the amount of current supplied to 51a to 58a.

For example, as shown by a dashed line in FIG. 3, when the temperature of the rotary drum 47 and each of the coils 51a to 58a is equal to or higher than a predetermined temperature, even if the vehicle speed V is equal to or higher than the predetermined speed V1, (For example, 5
(A current value of 0%). And
When the vehicle speed V reaches the predetermined speed V1 from this state,
Control is performed so that the current value becomes smaller than the current value immediately before reaching the predetermined speed V1.

[0023]

As described above, according to the control apparatus for an eddy current brake of the present invention, when the rotation speed of the rotating body detected by the rotation speed detecting means becomes equal to or lower than the predetermined rotation speed, the detection is performed. Control is performed to reduce the amount of power to the eddy current generating coil by the power supply limiting means according to the rotation speed.
By reducing the amount of current supplied to the eddy current generating coil in this manner, the braking force of the eddy current brake gradually decreases, so that the braking by the eddy current brake is not suddenly released, and the driver can A braking feeling without discomfort can be obtained.

The vehicle speed is 0 because the vehicle is stopped.
In other words, when the rotation speed of the rotating body is 0, the current supplied to the eddy current brake is also 0, so that it is possible to prevent unnecessary consumption of the power of the battery that is the power supply source. Further, by performing the above-described control, the amount of heat generated by the eddy current generating coil is also reduced, so that overheating of the eddy current generating coil can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of the control device for an eddy current brake according to the present invention, taken along the line II in FIG. 2;

FIG. 2 is a view of the eddy current brake controlled by the control device, as viewed from an arrow II in FIG. 1;

FIG. 3 is a graph showing a concept of control in the control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Vehicle speed sensor (rotation speed detection means) 12 Retarder operation switch 13 Controller (energization restriction means) 40 Eddy current retarder (Eddy current brake) 47 Rotating drum (Rotating body) 51-58 Electromagnet 51a-58a Eddy current generating coil

Claims (1)

[Claims] A rotating body formed of a ferromagnetic material and an electromagnet, wherein the rotating body is disposed so as to cross a magnetic flux generated from the electromagnet, and the rotating body is generated by an eddy current generated in the rotating body. In an eddy current brake configured to brake rotation, a rotation speed detection unit that detects a rotation speed of the rotating body, and the rotation speed detected by the rotation speed detection unit is equal to or less than a predetermined rotation speed. A control device for controlling the eddy current generating coil of the electromagnet in accordance with the detected number of rotations to reduce the amount of current supplied to the eddy current generating coil. .