JPH0475481A - Supermagnetostrictive type brake - Google Patents

Abstract

PURPOSE:To provide excellent heat resistance, and to be scarcely affected by heat even if brake oil becomes a high temperature by molding a rod as a drive source for regulating the volume of a volume regulating member of a supermagnetostrictive material. CONSTITUTION:When wheels start to lock, a wheel speed sensor senses it, an ABS controller conducts a magnetic field regulating coil 11 of a volume regulating member 9 and varies a conducting amount, thereby regulating the intensity of a magnetic field to be applied to a supermagnetostrictive rod 10. Thus, brake oil flowing volume in a cylinder chamber 3 is increased, an inner pressure in the chamber 3 is reduced, pressing forces for pressing frictional pads 6, 7 to both sides 2A, 2B of a disc 2 are reduced to reduce a braking force, thereby eliminating locking of the wheels. If the rotating speed of the wheels is increased, conduction of the coil 11 is stopped, the volume of the member 9 is increased to raise the inner pressure in the chamber 3, pressing forces for pressing the pads 6, 7 to both sides 2A, 2B of the disc 2 are increased to increase a braking force.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, an anti-skid brake system (
The present invention relates to a giant magnetostrictive brake device which is suitably used for applications (hereinafter referred to as rABsJ), and in particular uses a giant magnetostrictive material as a drive source during ABS control.

[Prior Art] Generally speaking, among brake devices for ABS equipped with a volume adjustment member installed in a brake cylinder chamber to adjust the volume of the brake cylinder chamber to perform ABS control, the following floating caliper type brake devices are used: There is something like that. That is, the brake device includes a caliper movably attached to a mounting bracket so as to cover both sides of a disc integrally attached to the wheel from the outer circumferential side thereof, and a cylinder chamber formed on one side of the caliper. , is supported by the mounting bracket with the piston slidably mounted in the cylinder chamber and the disc sandwiched therebetween, and due to the displacement of the piston, the piston and the caliper are pressed on both sides of the disc, thereby pushing the disc. A pair of friction pads that are frictionally clamped from both sides to apply braking force, and a volume that is installed in the cylinder chamber and expands and contracts in the cylinder chamber so that brake oil can flow into the cylinder chamber (hereinafter referred to as "brake oil inflow volume"). It is composed of a volume adjusting member that adjusts the size of the container. As the volume adjusting member, a piezoelectric element that expands and contracts by adjusting the applied voltage is generally used.

With the above configuration, by adjusting the voltage applied to the piezoelectric element, the piezoelectric element is expanded and contracted, and its volume is changed, thereby changing the brake oil inflow volume in the cylinder chamber. As a result, the pressure inside the cylinder changes, and the clamping force with which each friction pad frictionally clamps the disk is adjusted, thereby performing ABS control.

[Problem to be solved by the invention] By the way, in the brake device according to the prior art described above,
A piezoelectric element is used as the volume adjusting member, but the high temperature reliability of this piezoelectric element is limited to about 120°C.

On the other hand, when the brakes are used more frequently, the brake oil is heated by the heat generated by the friction between the disc and the friction pad, and the volume adjustment member is also heated together with the brake oil, resulting in high temperatures that may prevent it from functioning correctly. There is a problem in that the reliability of the brake device is low.

The present invention has been made in view of the problems of the prior art described above, and it is an object of the present invention to provide a highly reliable giant magnetostrictive brake device that can function stably even under high temperatures.

[Means for Solving the Problems] The configuration adopted by the present invention in order to solve the above-mentioned problems includes a brake cylinder in which a cylinder chamber is formed, and a piston that is slidably mounted in the cylinder chamber of the brake cylinder. and brake oil is supplied into the cylinder chamber,
a pair of friction pads that apply braking force by frictionally pinching the disc from both sides when the piston is displaced; and a volume that is disposed within the cylinder chamber and adjusts the volume into which brake oil can flow into the cylinder chamber. The volume adjusting member consists of a giant magnetostrictive rod that expands in proportion to the strength of the magnetic field when a magnetic field is applied, and a giant magnetostrictive rod that surrounds the giant magnetostrictive rod. It consists of a magnetic field adjustment coil that adjusts the strength of the magnetic field applied to the rod and causes the rod to expand and contract, and an elastic magnet member provided so as to surround the magnetic field adjustment coil and the giant magnetostrictive rod.

[Function] With the above configuration, the giant magnetostrictive rod is extended to a certain length in advance by the magnetic field of the elastic magnet member, and the volume adjusting member is maintained at a constant volume, and the volume adjusting member adjusts the brake oil inflow volume in the cylinder chamber. is maintained constant. Then, by adjusting the amount of current applied to the magnetic field adjustment coil, the strength of the magnetic field applied to the giant magnetostrictive rod is changed, the length of this rod is adjusted, the volume of the volume adjustment member is changed, and the brake inside the cylinder chamber is adjusted. Adjust the size of the oil inflow volume. This changes the cylinder chamber pressure, changes the force with which each friction pad presses both sides of the disk, and performs ABS control.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

First, to explain giant magnetostrictive materials, these magnetostrictive materials include neodymium (Nd)-iron alloys and dysprosium (Dy
)-iron, terbium (Tb)-iron alloy, etc. Further, FIG. 2 shows the relationship between the strength of the magnetic field applied to the giant magnetostrictive material and the magnetostriction value (the amount of deformation of the giant magnetostrictive material), and the characteristic line P in the figure. is the change characteristic of the magnetostriction value when a magnetic field is applied to the giant magnetostrictive material without applying an external pressure in the axial direction to the giant magnetostrictive material as a preload, and the characteristic line P is 0.7 kg/mm for the giant magnetostrictive material.
The change characteristic of the magnetostriction value when a magnetic field is applied to this giant magnetostrictive material with a preload of 1.
The characteristics of changes in the magnetostriction value when a magnetic field is applied to this magnetostrictive material under a preload of 4 kg/II are shown. These characteristic lines PG, PI.

As can be seen from P2, when a magnetic field is applied to the giant magnetostrictive material with a preload applied, the magnetostriction value increases (changes and
Regardless of the direction of the applied magnetic field, the magnetostriction value changes depending on the absolute value of the magnetic field. Furthermore, giant magnetostrictive materials are difficult to be affected by heat (for example, piezoelectric elements can only withstand temperatures of about 120°C, whereas giant magnetostrictive materials can withstand temperatures of about 180°C), and their properties are not very strong even under high heat. It has the advantage of not changing.

The giant magnetostrictive brake device of this embodiment uses the giant magnetostrictive material having the above-described characteristics as a drive source for the volume adjusting member, and has the configuration shown in FIG. 1.

In the figure, reference numeral 1 indicates a disk 2 integrally attached to a wheel (not shown) from the outer circumferential side of both sides 2A, 2 of the disk 2.
A caliper serving as a brake cylinder is movably attached to a mounting bracket (not shown) so as to cover the caliper 1. The caliper 1 has a cylinder part IA formed on one side thereof and defining a cylinder chamber 3 to be described later. formed integrally with the cylinder portion IA and on the other side across the outer periphery of the disk 2;
It is composed of a pad pressing section 1B that presses a friction pad 7, which will be described later.

3 is a cylinder chamber formed in the cylinder part IA,
The cylinder chamber 3 is formed with an opening on the disk 2 side, and two communication holes 3A and 3B are provided on both sides of the cylinder chamber 3, which communicate with a mask cylinder (not shown) via a brake pipe 4.

5 is a piston slidably mounted in the cylinder chamber 3;
A friction pad 6 that presses one side surface 2A of the disk 2 is in contact with the tip of the piston 5. Further, a friction pad 7 that is pressed against the other side surface 2B of the disk 2 is brought into contact with the pad pressing portion IB of the caliper 1, and each friction pad 6.
The disc 2 is frictionally clamped at 7 to provide braking force. Note that 8 indicates an O-ring that is provided on the base end side of the piston 5 and seals between the piston 5 and the inner circumferential surface of the cylinder chamber 3.

Reference numeral 9 denotes a volume adjusting member that is installed in the cylinder chamber 3 so as to define one side chamber 3C and the other side chamber 3D, and adjusts the brake oil inflow volume in the cylinder chamber 3. The volume adjusting member 9 is
A giant magnetostrictive rod 10 formed of the giant magnetostrictive material, which expands by a length proportional to the strength of the magnetic field when a magnetic field is applied.
The giant magnetostrictive rod 10 is provided so as to surround it, and by applying an electric current, a magnetic field is applied to the giant magnetostrictive rod 10 to cause it to elongate, and by changing the strength of this magnetic field, the rod 1
A magnetic field adjusting coil 11 for adjusting the amount of extension of 0 is provided so as to surround the magnetic field adjusting coil 11 and the giant magnetostrictive rod 10, and a constant magnetic field is applied to the giant magnetostrictive rod 10 in advance,
It is composed of an elastic magnet member 12 that maintains the giant magnetostrictive rod 10 at a constant length, and as the giant magnetostrictive rod 10 expands and contracts, the elastic magnet member 12 is expanded and the volume of the volume adjusting member 9 changes. ing. moreover,
The elastic magnet member 12 is formed of a flexible magnet such as an elastic rubber magnet, a plastic magnet, or a nylon magnet, and applies a certain preload (for example, 0.7 to 1.4 kg) to the giant magnetostrictive rod 10.
/++m''), and allows the giant magnetostrictive rod 10 to expand and contract due to its own elasticity, allowing it to expand and contract together.

The strength of the magnetic field of the elastic magnet member 12 is set, for example, at point A in FIG.
It will start to expand. Reference numerals 13 and 14 indicate O-rings provided at both ends of the outer circumference of the elastic magnet member 12 to seal between the elastic magnet member 12 and the inner circumferential surface of the cylinder chamber 3.

Further, the volume adjusting member 9 is connected to one side chamber 3C which communicates the inside of the cylinder chamber 3 covered by the piston 5 with one of the communication holes 3A.
and another side chamber 3D communicating with the other communication hole 3B, and the magnetic field adjustment coil 11 is electrically connected to an ABS control device (not shown).

The giant magnetostrictive control valve of this embodiment is constructed as described above, and its operation will be explained next.

Normally, the magnetic field adjustment coil 11 of the volume adjustment member 9 is not energized, the giant magnetostrictive rod 10 is maintained at a constant length by the elastic magnet member 12, and the volume adjustment member 9 has a constant volume. The brake oil inflow volume in the cylinder chamber 3 (the volume of the negative side chamber 3C and the other side chamber 3D) is maintained constant.

During braking, brake oil from the mask cylinder is supplied to both side chambers 3C, 3D via the brake piping 4 and each communication hole 3A, 3B, and presses the volume adjustment member 9 from both side chambers 3C, 3D. The brake oil flowing into the other side chamber 3D pushes the piston 5 and presses one friction pad 6 against the one side surface 2A of the disc 2. and,
Due to the reaction force against the pressing force of the friction pads 6, the caliper 1 is displaced to one side while being supported by the mounting bracket, and presses the other friction pad 7 against the other side surface 2B of the disk 2, causing each of these friction pads 6.7 The disc 2 is frictionally clamped from both sides 2A and 2B to generate braking force.

On the other hand, when the wheels start to lock, a wheel speed sensor (not shown) attached to the wheels detects this, and the ABS control device energizes the magnetic field adjustment coil 11 of the volume adjustment member 9 and adjusts the amount of energization. The strength of the magnetic field applied to the giant magnetostrictive rod 10 is adjusted by changing the magnetic field. Specifically, the magnetic field adjustment coil 11 is energized so that a magnetic field is generated in a direction that cancels the magnetic field produced by the elastic magnet member 12, and the giant magnetostrictive rod 10 is accommodated to reduce the volume of the volume adjustment member 9. The brake oil inflow volume in the chamber 3 becomes large (as a result, the internal pressure in the cylinder chamber 3 decreases, and the pressing force that presses each friction pad 6.7 against both sides 2A and 2B of the disc 2 via the piston 5 becomes smaller, resulting in a control effect). The power is reduced and the wheels are unlocked.Then, as the rotational speed of the wheels increases,
Stop energizing the magnetic field adjustment coil 11, or energize it so that a magnetic field is generated in the same direction as the elastic magnet member 12, increase the volume of the volume adjustment member 9, and reduce the brake oil inflow volume in the cylinder chamber 3. Then, the internal pressure of the cylinder chamber 3 is increased, and each friction pad 6.7 is applied to both sides 2A of the disk 2 via the piston 5.

The braking force is increased by increasing the pressing force against 2B. Then, the above control is repeated to perform ABS control.

As described above, in the giant magnetostrictive brake device of this embodiment, the rod 1 serves as a drive source for adjusting the volume of the volume adjusting member 9.
Since it is made of giant magnetostrictive material, it has excellent heat resistance and is hardly affected by heat even when the brake oil reaches a high temperature, and it operates reliably even in high-temperature brake oil, greatly improving safety. As a result, reliability of the device is improved.

Further, an elastic magnet member 1 having elasticity is used as a magnet for applying a certain magnetic field to the giant magnetostrictive rod 10 in advance.
2 is used, the elastic force of the elastic magnet member 12 allows a certain preload to be applied to the giant magnetostrictive rod 10, and there is no need for a special member for applying preload to the giant magnetostrictive rod 10, reducing the number of parts. , cost reduction can be achieved.

Furthermore, since the elastic magnet member 12 itself has elasticity and can expand and contract, even if the giant magnetostrictive rod 10 expands and contracts,
By allowing this to expand and contract together, problems such as cracking of the magnet can be reliably solved.

In addition, in this embodiment, the giant magnetostrictive rod 10 is
The strength of the magnetic field of the elastic magnet member 12 is set so that the magnetostriction value is at a point, and the magnetostriction value is set to increase (change) as the magnetic field changes. In this case, a region where the rate of change of magnetostriction value is small (for example, point B)
The strength of the elastic magnet member 12 may be set so that . Thereby, it is possible to reduce the change in the magnetostriction value with respect to the change in the magnetic field, and it is possible to perform more accurate and delicate adjustment of the internal pressure of the cylinder chamber 3. Here, the setting value of the elastic magnet member 12 was set to the plus side in FIG.
Needless to say, it can be on the negative side.

Further, in this embodiment, a floating caliper type (single piston type) disc brake is explained as an example, but the present invention is not limited to this, and an opposed piston type (objected type) disc brake may also be used. , it is only necessary to provide a volume adjusting member in each cylinder chamber of the brake cylinder, and the same functions and effects as those of the previous embodiment can be achieved.

Effects of the Invention 1 As detailed above, 1 According to the present invention, since the rod serving as the drive source for adjusting the volume of the volume adjusting member is molded from giant magnetostrictive material, it has excellent heat resistance and the brake oil does not reach high temperatures. It is not easily affected by heat (even in high-temperature brake oil) and operates reliably, greatly improving safety.

In addition, since an elastic magnet member having elasticity is used as a magnet to apply a constant magnetic field to the giant magnetostrictive rod in advance, the elastic force of this elastic magnet member makes it possible to apply a certain preload to the giant magnetostrictive rod. No special member is required to apply preload to the rod, reducing the number of parts and reducing costs.

The countersunk ζ elastic magnet member itself has elasticity and can expand and contract, so even if the giant magnetostrictive rod expands and contracts, it will tolerate it and expand and contract together, reliably solving problems such as cracks in the magnet. .

[Brief explanation of drawings]

1 and 2 relate to embodiments of the present invention, FIG. 1 is a longitudinal cross-sectional view showing a giant magnetostrictive brake device, and FIG. 2 shows the strength of the magnetic field applied to the giant magnetostrictive material and the strength of the giant magnetostrictive material. FIG. 3 is a characteristic line diagram showing the relationship with magnetostriction value. 1... Caliper, 2... Disc, 3... Cylinder chamber, 5... Piston, 6.7... Friction pad, 9
...Volume adjustment member, 10... Giant magnetostrictive rod, 11.
...Magnetic field adjustment coil, 12...Elastic magnet member.

Claims (1)

[Claims] a brake cylinder in which a cylinder chamber is formed; a piston slidably mounted in the cylinder chamber of the brake cylinder; brake oil is supplied into the cylinder chamber;
a pair of friction pads that apply braking force by frictionally pinching the disc from both sides when the piston is displaced; and a volume that is disposed within the cylinder chamber and adjusts the volume into which brake oil can flow into the cylinder chamber. The volume adjusting member consists of a giant magnetostrictive rod that expands in proportion to the strength of the magnetic field when a magnetic field is applied, and a giant magnetostrictive rod that is provided so as to surround the giant magnetostrictive rod, and that expands when energized. A giant magnetostrictive type consisting of a magnetic field adjusting coil that adjusts the strength of a magnetic field applied to a magnetostrictive rod and expands and contracts the rod, and an elastic magnet member provided so as to surround the magnetic field adjusting coil and the giant magnetostrictive rod. Brake device.