JPS63292001A - Abrasion-sensitive ball joint - Google Patents

Abstract

PURPOSE:To obtain a device which makes it unnecessary to conduct fine adjustment for offsetting a direct-current offset part of a Hall element different for each device after a ball joint is assembled, by a method wherein the Hall element is driven by a pulse and an alternating-current output voltage thereof is amplified by an alternating-current amplifier. CONSTITUTION:A Hall element 9 sensing a magnetic force of a permanent magnet 8 is joined and fixed on the surface on the antiabrasion compensation bearing side of a closing plate 7. When a ball joint 1 surfers an abnormal abrasion, a head part 3 is moved relatively in the direction of a socket opening by the resilience of an abrasion compensation bearing 6. The magnet 8 recedes from the element 9 with this movement, a sensed density of a magnetic flux becomes small, an output voltage of the Hall element lowers, and the pulse amplitude of an output voltage of an alternating-current amplifier 13 lessens. Therefore, an output of a comparator 15 becomes zero, and a transmitter 16 transmits 17 only a carrier wave. This electric wave signal is received by a receiver, and a monitoring device provided for an operator displays that the joint 1 reaches the limit of abrasion.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to sensing internal wear in ball joints used, for example, in automobile suspension systems.

Conventional technology A conventional technology for detecting internal wear of a ball joint, as disclosed in Japanese Patent Application No. 60-273622 filed by the present applicant, includes providing a permanent magnet inside the ball joint and opposing the permanent magnet. Some ball joints have a Hall element placed at a suitable location on the outer periphery of the ball joint to sense the magnetic force of a permanent magnet.

In this ball joint, a permanent magnet is moved in response to internal wear of the ball joint, and the wear limit inside the ball joint is detected by detecting magnetic force that changes as the permanent magnet moves.

Problems to be Solved by the Invention Incidentally, even if Hall elements are of the same standard, each element has a different DC offset voltage, so it is necessary to cancel this DC offset voltage with a DC bias circuit or the like.

In order to cancel this DC offset voltage, there is a problem in that offsets that differ for each element must be finely adjusted and canceled after the ball joint is assembled.

The only way to solve the problem is to pulse-drive the Hall element and amplify the AC output voltage of the Hall element with an AC amplifier.

An AC voltage proportional to the magnetic flux density is output from the working Hall element, and the DC offset voltage is removed from the output by an AC amplifier.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a lower ball joint 1 used in a front suspension of an automobile.

This ball joint 1 includes a stud 2, a socket 4,
It includes a load support bearing 5, a wear compensation bearing 6, and a closing plate 7.

The socket 4 has a cylindrical shape and has openings at both ends, one of which is closed by a closing plate 7, and the other opening allows the handle of the stud to protrude swingably.

The closing plate 7 is made of a rigid non-magnetic material such as stainless steel or aluminum alloy.

The stud 2 has a spherical head 8 at one end of the handle.

The head 3 of the stud is arranged in the socket 4 with the half on the handle side supported by a load-bearing bearing 5 and the half on the side opposite to the handle supported by a wear compensation bearing 6.

Moreover, the head 3, together with the wear compensation bearing 6, is constantly pressed toward the socket opening by a push-up annular portion made of an elastic material such as rubber that is compressed by the attachment of the closing plate 7.

Therefore, while the ball joint 1 is in use, the head 3 or the bearing 5
, 6 are worn, the wear compensation bearing 6 will move relatively toward the socket opening.

Furthermore, the load supporting bearing 5 and the wear compensation bearing 6 are suitably selected from resins with excellent wear properties such as nylon, polyethylene, polyacetal and polyurethane.

A permanent magnet 8, which will be described later, is disposed on the bottom surface of the wear compensation bearing 6 on the side opposite to the spherical seat surface. The magnetic field formed by this permanent magnet extends outside the closing plate 7 made of non-magnetic material.

The closing plate 7 is fixed to the socket opening by deforming the peripheral edge of the socket opening by caulking onto the closing plate 7.

A Hall element 9 serving as a magnetic force sensing device for sensing the magnetic force of the permanent magnet 8 is coupled and fixed to the side surface of the closing plate 7 on the anti-wear compensation bearing side.

On the closing plate T, a battery 10 and an electronic circuit 11 are placed outside.
is fixed.

Furthermore, FIG. 2 shows a detector, which is composed of a permanent magnet 8 shown in FIG. 1, a Hall element 9, a battery 10, and an electronic circuit 11 including devices described later, and detects changes in magnetic flux density. to detect the wear condition inside the ball joint.

Reference numeral 12 denotes a pulse excitation generator which, when supplied with a constant current, generates a pulse current of a predetermined frequency and constant current and supplies it to the Hall element 9 .

13 is an AC amplifier that removes the DC offset voltage from the AC output voltage of the Hall element 9 (Fig. 3) and increases the
The resulting pulse voltage is output (Fig. 4).

Therefore, it is no longer necessary to fine-tune and offset the DC offset of each Hall element, which varies from Hall element to Hall element, after assembly.

15 is a comparator, which compares the wear limit voltage set by the setting device 14 and the output of the AC amplifier 13, and outputs the comparison result (
Figure 5).

A transmitter 16 subjects the output of the comparator 15 to F Bi modulation and outputs it from an antenna 17.

Next, wear detection in the ball joint will be explained.

If the ball shield 1 were to suffer abnormal wear during use, the resilient force of the wear compensation bearing 6 would cause the head 3 to move relative to the opening direction of the socket.

Along with this, the permanent magnet 8 also moves away from the Hall element 9,
The sensed magnetic flux density decreases.

As a result, the Hall element output voltage decreases as shown in FIG. Therefore, the pulse amplitude of the output voltage of the AC amplifier 13 is reduced as shown in FIG.

As a result, the output of the comparator 15 becomes zero as shown in FIG. 5, and the transmitter 16 transmits only the carrier wave.

This radio signal is received by a receiver (not shown), and is displayed on a monitor in the driver's seat to indicate that the ball joint 1 has reached its wear limit.

Effects As described above, according to the present invention, an AC voltage proportional to the magnetic flux density is output from the Hall element, and the DC offset voltage is removed from the output by the AC amplifier. There is no need to make fine adjustments to offset the offset after assembling the ball joint.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a cross-sectional plan view of a ball joint. FIG. 2 is a diagram explaining the principle of the wear detector. 3 to 5 are waveform diagrams of output voltages. (Explanation of symbols) 1...Ball joint. 8...
1 permanent magnet. 9...Hall element. 13...AC amplifier. Figure 1

Claims (1)

[Claims] A permanent magnet 8 is provided inside the ball joint 1, and a Hall element 9 is provided at a suitable location on the outer periphery of the ball joint to face the permanent magnet 8 and sense the magnetic force of the permanent magnet 8.
A wear-sensing ball joint characterized in that the Hall element 9 is pulse-driven, the AC output voltage of the Hall element is amplified by an AC amplifier 13, and the amount of wear is sensed based on the remaining amplitude level.