CN100335810C - Magnetic circuit of electromagnet of vehicle electromagnetic brake - Google Patents

Abstract

The present invention relates to the technical field of automobiles, particularly to the shape of an electromagnet magnetic circuit which is a functional component of a brake of an automobile. The brake is especially suitable for automobile dragging braking for a house automobile. The present invention is characterized in that an asymmetric magnetic circuit corresponding to an elliptical major axis is adopted, the magnetic density of the magnetic circuit is designed within the linearity range of a B-H characteristic curve, grooves are arranged on the internal side of the magnetic circuit, the depth of each of the grooves is from 2 to 3mm, the width of each pf the grooves is from 2 to 2.5mm, and the grooves are uniformly distributed on the internal side of the magnetic circuit. The present invention has the advantages that the effect on wear, which is caused when the internal side magnetic attraction is greater than the external side magnetic attraction, counteracts the effect on the wear, which is caused when the internal side speed is lower than the external side speed, and the present invention works. The nonuniform wear is overcome, the service life is extended, the moment with a rotating inclination is simultaneously reduced, and the working reliability is improved.

Description

A kind of electromagnet of vehicle electromagnetic brake

Technical field

The present invention relates to the vehicle technology field, refer in particular to a kind of functional part electromagnet magnetic circuit of electromagnet design of vehicle brake, this break is particularly useful for the trailer brake of GT grand touring.

Background technique

At present, there are many patents that the performance of electromagnet has been done improvement abroad, provided as the patent patnet4014412 of U. S. Patent warnnel electromagnetic brake in 1977 clutch company and prevented that electromagnet itself from rotating the mechanical structure of tendency; Another U. S. Patent becomes accurate ellipse to electromagnet design, and the friction material of filling about the minor axis distribution or asymmetrical distribution, has improved the problem of non-uniform of wearing and tearing before and after antidumping moment and the moving direction on rubbing surface.But the magnetic circuit of electromagnet is about accurate transverse symmetry.By braking process as can be known, electromagnet is that the friction of circumference slide relative is done in the center of circle with the rotating disc center of brake drum during braking, and the outside of electromagnet rubbing surface and inboard have caused the linear velocity difference owing to moving radius is different.And about the magnetic circuit of transverse symmetry, the electromagnetic force in the outside is identical in making, thereby makes rate of wear difference.Report is arranged, scrap, influenced the life-span owing to symmetrical magnetic circuits at first weares and teares the electromagnet outside coil is exposed on one side.In addition, by circle Motion Analysis as can be known, electromagnet self about the transverse symmetrical magnetic circuits certainly leads to the moment that causes cyclovergence, though the cross link joint hole of the connection lever system at electromagnet center has prevented the electromagnet rotation, but the moment of cyclovergence makes the link joint place produce bigger stress, generation is stuck easily, the influence braking.Patent 2004200784379 adopts the method for outside magnetic circuit sectional area difference (so magnetic resistance difference) in the electromagnet to change the size of electromagnetic force, reach the purpose of wearing and tearing evenly and reducing cyclovergence, but this method has 3 deficiencies: 1) sectional area becomes a big side, the space of placing coil diminishes, the Number of ampere turns of coil is restricted, and total electromagnetic force is little.2) do not consider the effective air gap problem of magnetic circuit between rubbing surface, actual measurement and calculating show that effective air gap exists, so the asymmetric effect of actual electrical magnetic force diminishes.3) deviation of gravity center is in the connection place of geometrical center, causes the gravity unbalance factor.

Summary of the invention

The objective of the invention is to overcome above-mentioned deficiency, provide a kind of inboard suction greater than outside suction, the electromagnet that inboard speed offsets the influence of wearing and tearing less than outside speed during with work, it does not change with effective air gap diminishes the asymmetric effect of electromagnetic force.

Know-why of the present invention is:

During the braking of break, electromagnet powers up the electromagnetic force of generation, make electromagnet be drawn onto with the brake drum of wheel rotation make the outer side surface of rotary end surface by ferromagnetic material, form closed magnetic circuit.The rotation of brake drum drives electromagnet and moves.Frictional force therebetween makes the brake lever that connects with the movable cross of electromagnet produce displacement, and the other end of lever makes brake shoe produce displacement, realizes braking.After the end of braking, the electromagnet outage, shoe plate resets under the return spring effect.In the braking process, the force of sliding friction size between the rotating disc of electromagnet and brake drum is directly proportional with electromagnetic force suction, and its rate of wear is directly proportional with electromagnetic force, is directly proportional with the rubbing surface relative velocity.The structure of reliable, durable degree of electromagnet and electromagnet is relevant.Adopting asymmetrical magnetic Circuit Design, is target with the equalising torque, and the asymmetric magnetic circuit of designing about electromagnet rubbing surface minor axis distributes, thereby the rubbing surface wearing and tearing evenly do not have the tendency of toppling before and after making the electromagnet motion.Method with fluting is proposed, make about the inboard electromagnetic force of electromagnet rubbing surface major axis greater than outside electromagnetic force, compensated electromagnet outer side surface friction velocity greater than the caused uneven wear of inner side surface, reduced cyclovergence simultaneously, the suffered moment of torsion in electromagnet connection place is reduced greatly, improved functional reliability.

Technological scheme of the present invention is:

The present invention adopts the asymmetric magnetic circuit about transverse, and the close characteristic linearity range of B-H that is designed in of magnetic circuit of electromagnet magnetic is slotted on inboard magnetic circuit, and groove depth is 2～3mm, and every well width is 2～2.5mm, and is uniform on this side magnetic circuit.

The uniform fluting of the inboard magnetic circuit of electromagnet is removed area percentage and is:

$\frac{2D}{{4R}_0+3D}\×100\%$

R in the formula ₀Be the radius of rotating center to the electromagnet inner side edge, D is the electromagnet minor axis dimension.

Because the fluting size is little, very little to the influence of the permeance of inside and outside both sides magnetic circuit, can think that the both sides magnetic resistance equates, thus the magnetic flux φ of both sides equate, and do not influence the φ symmetry properties because of the air gap of magnetic circuit between rubbing surface.

The realization of asymmetric magnetic circuit scheme, can solve by following formula:

During work, the rate of wear is proportional to FV/A (wherein F is a frictional force, and V is the relative velocity of rubbing surface, and A is a friction area).Electromagnet equates about the interior outer friction surface area of transverse, then by the electromagnetic force calculating formula $F=\frac{{\mathrm{\φ}}^2}{2{\mathrm{\μ}}_{0}S}$ And uniform wear condition μ F ₁R ₁=μ F ₂R ₂(R ₁, R ₂Outside single force point of action in being respectively, μ is a friction factor, F ₁, F ₂The electromagnetism that is respectively inside and outside both sides is made a concerted effort), can derive:

$\frac{F_1}{F_2}=\frac{S_2}{S_1}=\frac{{4R}_0+3D}{{4R}_0+D}$

S in the formula ₁, S ₂Be respectively the magnetic circuit sectional area of inside and outside dual-side.

The groove area percentage removed of the inboard magnetic circuit of uniform fluting then:

$\frac{2D}{{4R}_0+3D}\×100\%$

This design method about the asymmetric magnetic circuit of major axis, make inboard electromagnetic attraction greater than the outside, therefore when braking, the inboard suffered frictional force of electromagnet is greater than the outside, produce a running torque, it is opposite with the running torque direction that electromagnet is produced because of the rotation of brake drum end face, thereby has weakened cyclovergence, makes brake drum steadily, reliably.

Advantage of the present invention is: owing to adopt the method for fluting to make magnetic circuit of electromagnet asymmetric about the magnetic circuit of transverse, except making inboard suction greater than outside suction, thereby it is inhomogeneous to have overcome wearing and tearing, prolonged the working life of electromagnet, reduced the moment of cyclovergence, improved outside the reliability of work, and do not influenced the asymmetry of its suction, overcome 3 deficiencies of patent 2004200784379 because of magnetic air gap between rubbing surface.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples

Fig. 1 is an electromagnet profile schematic representation.

Fig. 2 is the worm's eye view of Fig. 1.

Among the figure: 1, electromagnet, 2, electromagnet newel magnetic circuit, 3, cross link joint hole, 4, outside magnetic circuit, 5, inboard fluting magnetic circuit, 6, friction material, 7, groove.

Symbol R wherein ₁Be inboard single force radius, R ₂Be outside single force radius, R ₀Be the distance of brake disc rotating center to the electromagnet inner side edge, h is the electromagnet height, and D is a minor axis length.In addition, F ₁For electromagnetic attraction is made a concerted effort, F ₂For the brake drum end face is made a concerted effort F to the support reaction of electromagnet ₃For frictional force is made a concerted effort, F ₄Be the equivalent action power of bindiny mechanism to electromagnet.F ₅For concentrating frictional force, F in the inboard ₆Concentrate frictional force for the outside, ω is the brake disc sense of rotation.

Embodiment

Shown in accompanying drawing 1,2, it is accurate oval that electromagnet of the present invention (1) is, and its electromagnet newel magnetic circuit (2) center is cross link joint hole (3).

Its mode of execution is: adopt the asymmetric fluting magnetic circuit of transverse; Fluting (7) on inboard magnetic circuit, groove (7) is uniform, the end face of filling friction material (6) and Fig. 2 finding outside magnetic circuit (4), inboard fluting magnetic circuit (5) and newel magnetic circuit (2) forms rubbing surface together, and this packing material adopts the good resinous material of frictional behaviour.

Specific embodiment: 12 o'clock breaks, with formula

Inboard magnetic circuit is opened 20% area.

Among the figure, F ₁, F ₂With F ₃, F ₄Two pairs of equalising torques that form overcome the problem of non-uniform of wearing and tearing before and after tilting moment and the moving direction.F ₅Greater than F ₆Compensate electromagnet outer side surface friction velocity greater than the caused uneven wear of inner side surface, reduced cyclovergence simultaneously, the suffered moment of torsion in electromagnet connection place is reduced greatly, improved functional reliability.

Claims (3)

1. the electromagnet of an electromagnetic vehicle break, it is accurate oval that electromagnet (1) is, its newel magnetic circuit (2) center is cross link joint hole (3), the end face of filling friction material (6) and outside magnetic circuit (4), inboard magnetic circuit (5) and newel magnetic circuit (2) in the electromagnet (1) forms rubbing surface together, it is characterized in that on inboard magnetic circuit, slotting, and magnetic circuit of electromagnet is in the characteristic linearity range of B-H.

2. the electromagnet of a kind of electromagnetic vehicle break according to claim 1 is characterized in that the definite of removal area of the inboard magnetic circuit fluting of electromagnet guaranteed by following formula: $\frac{F_1}{F_2}=\frac{S_2}{S_1}=\frac{4R_0+3D}{{4R}_0+D}$ The percentage of promptly removing area is: $\frac{2D}{4R_0+3D}\×100\%$

S in the formula ₁, S ₂Be respectively the magnetic circuit sectional area of inside and outside dual-side, R ₀Be the radius of rotating center to the electromagnet inner side edge, D is the electromagnet minor axis dimension, F ₁For the inboard electromagnetic force of electromagnet is made a concerted effort F ₂For electromagnet outside electromagnetic force is made a concerted effort.

3. the electromagnet of a kind of electromagnetic vehicle break according to claim 1 is characterized in that described groove depth is 2～3mm, and every well width is 2～2.5mm, and uniform on this side magnetic circuit.

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