US2548809A - Wheel balancer pickup unit - Google Patents

Description

April 10, 1951 H. M. NORMAN 2,548,809

WHEEL BALANCER PICKUP UNIT Filed Sept. 22, 1948 nim/g 77 r, 98 ,V l n v wsu/WQ I alan-1 69S.

Patented pr. 10, 1951 UNITED STATES PATENT OFFICE WHEEL BALANCER PICKUP UNIT Application September 22, 1948, Serial No. 50,623

(Cl. 20G-52) Claims.

The present invention deals with an arrangement whereby the vibratory motion of an out of balance rotating member may be translated into a series of electrical pulses which are in phase with the vibration. The operation depends on the viscous friction of a fluid between a lapped shaft and a sleeve. In the past a pickup unit of the dashpot type has been employed. The present invention has all the advantages of this system and many more of its own.

One of the primary objects of the present invention is to provide an improved device for locating unbalance in wheels.

Another object is to provide `a, balancing switch which is cheap and accurate and easily adjustable.

A further object is to provide a single switch which can be used in the vertical or horizontal direction with no adjustments.

Another object is to provide a switch which has a minimum friction and which has equal resistance in the open and close position.

Another object is to provide a wheel balance pickup which will correct for any shift of the car while the wheel is rotating.

Other objects and advantages ywill appear in the subsequent disclosure.

In the discussion of this switching apparatus the following gures will be referred to:

Fig. 1 is a general view of the pickup unit only, without the electrical contacts.

Fig. 2 is a view showing the construction of the contacts.

Fig. 3 is another view showing a modication of the contacts of Fig. 2.

The principle underlying the invention is that when one of two members, having surfaces which are held close together with a fairly viscous uid between them, is moved at a certain speed, the other surface will move also.

As most clearly shown in Fig. 1, a permanent magnet I0 is provided as a convenient means for attaching the apparatus to the axle housing of the rotating wheel or other part which may vibrate. The magnet ID is carried by a yoke I2 at the end of an adjusting and supporting rod I4. This rod I4 telescopes into a sleeve I6, being held in adjusted position by a screw I 8. A universal connection between sleeve I 6 and a rod 24 is provided by a ball on the former and a socket 22 on the latter. At the other end of rod 24 is a sleeve 26 which is fastened securely to a shaft 28. The shaft 28 is lapped into a sleeve 30 and mounted on the bearings 32 and 34. A bracket 36 which holds an operating arm 38 is clamped to the sleeve 30.

Between the sleeve 30 and the shaft 28 is a uid 39 which has the property of almost constant viscosity under all temperature conditions. An example of such a fluid is one of the Silicone products known as DC20O which at 25 centigrade has a viscosity of 350 centistokes and has approximately constant viscosity over a wide range of temperature. The fit between the shaft 28 and the sleeve 3 is such that the fluid 39 will be retained between these parts by capillary action, thus there is need for only a dust proof casing (not shown) enclosing the unit.

In Figs. 2 and 3 are shown two types of switches that may be used with the pickup. In Fig. 2 the operating arm 38 terminates in an actuator 4|] of insulating material. This actuator is in contact with leaf spring arms 42 and 44 secured to stationary non-conductive supports 46 and 48. The free end of leaf spring 42 is supplied with a contact button 52 which is normally in contact with contact button 54. Contacter 54 is mounted on an arm 56 and secured to a non-conducting block 58. The other leaf spring 44 is in contact with contactor 62 which is mounted in arm 64. Arm 64 is fastened to a block 66 of non-conducting material. The blocks 46 and 48 have upper ends 'I0 `and 'I2 into which are rotatably mounted adjusting screws 'I4 and 16. The ends of these screws are threaded in the blocks 58 and 66 and may be held from rotation by tightening lock nuts 'II into engagement with brackets 46 and 48 respectively. Therefore, by turning the screws, the insulating blocks 58 and 66 may be adjusted to any position. The position most desirable is one in which the contacts have the least amount of pressure. The supports 46 and 48 have limit stop projections 41 and 49 which face toward the bracket 36 in order to keep the sleeve 30 from overtravel when the magnet I0 is subjected to large amplitude vibration.

The parts of the apparatus are in the position shown when no unbalance is present. When an oscillating motion is imparted to the contactor due to vertical vibratory movement of magnet IEJ, the contacts 52-54 will be separated periodically. Contacts 52-54 and lead 68 are connected in an indicating circuit, not shown in the drawing, but similar to one shown and described in the co-pending application of Arthur C. Allen Serial Number 748,049, led May 14, 1947, the contact 52 being connected in the circuit by a lead l0. This circuit will be broken every time the increased weight, causing unbalance of the rotating member, is at the bottom of its rotary cycle. The leaf spring arms 42 and 44 are of the 'same elasticity and will impart equal loads to the actuator 4E) as it moves in either direction from its central position. This tends to keep constant the phasing of the make break of the circuit at 52-54. By adjusting the contacts 54 and 64 until they just make Contact with the springs 42 and. 44 a very sensitive condition is possible. This may be checked for continuity by connect ing the lead lil to the arm 64 such that the contact between 62 and 44 is in series with contacts 52-54, and then adjusting the supports 58 and 656 until a sensitive make condition is present kand current just begins to ow.

Fig. 3 is a slight modification of Fig. 2 in that the actuator 4Q is replaced by a roller l2. This tends to eliminate any friction losses present in the system of Fig. 2 because as the arm 38 cscillates, the roller i2 can roll on the leaf spring arms 42 and 44.

This system has the great advantage over previous dashpot pickup units in that it can be used in the horizontal or vertical direction with the same set of contacts. By slowly swinging the arm 24 about the axis of shaft 28 to the vertical direction, one can check on unbalance along the axis of the wheel. The slow movement of the arm 2li will not tend to rotate the sleeve 3i? with the shaft 28.

In this type of system automatic centering of the arm 38 is one of the advantages. When the pickup magnet i9 is vibrating at frequencies of three cycles per second or more and has very short amplitude, then the sleeve and the shaft rotate as one piece. Below three cycles per second and for vibrations of high amplitude the shaft rotates within the sleeve. Thus a small shift of the axle to which the magnet IE) is attached will not rotate the sleeve, thereby not disrupting the phasing, and the higher frequency vibration due to unbaiance will continue to open and shut the contacts 52 and 54.

These embodiments of the invention are not to be construed as limiting it, but the invention is to be limited only in so far as the following claims do so.

I claim:

l. A vibration pickup apparatus comprising a pair of relatively rotatable parts bearing in one another and having a close t between them, a viscous liquid lling the space between the parts, a linkage including a radial arm xed to one of the parts for connecting the part to a vibrating element and producing rotation of the parts as a result of the vibration of the element, a generally radial arm fixed to the other of said parts, resilient means engaging the latter part to provide resilient resistance to rotation of said part in either direction, and a switch position for operation by said latter arm whenever it is moved in one direction.

2. In an apparatus for detecting unbalance in rotating bodies, a sleeve, a shaft extending through the sleeve and having a close t theren in, a pick-up arm extending radially from the shaft, a magnet and supporting arm therefor, a universal joint connecting the supporting arm to the pick-up arm whereby vibratory movement of the magnet will cause oscillation of the shaft, a viscous fluid between the shaft and the sleeve, an actuator arm mechanically connected to the sleeve, a pair of spring arms each supported at one end and having their free ends positioned in engagement with the actuator arm, a contact at the free end of one spring arm, an adjustable contact adjacent the spring arm contact, and an adjustable stop adjacent the free end of the second spring arm, whereby the first mentioned spring arm will be moved by the said actuator arm to open the contacts upon oscillation of the magnetic pick-up arm.

3. An apparatus for producing an electrical signal in response to the vibration of a body which may move beyond the range of its vibratory motion, comprising a pair of relatively rotatable closely spaced members, one within the other, a thin film of viscous liquid between said members and forming the only means for transmitting forces due to the vibration of the body from one of the members to the other, a linkage including a radial arm fixed to one of the members and means at the outer end of the arm for securing the arm to a vibrating body for translating the motion of the body into rotational motion of the member, a radial arm fixed to the other of said members, and a vibration pickup connected with the outer end of the latter arm for providing electrical signals in response to Vibrations of the arm.

AA self-aligning apparatus for connecting a vibrating body with a vibration pickup, comprising a pair of relatively rotatable parts having closely adjacent cylindrical surfaces, a viscous fluid positioned between the surfaces to provide intercouplingbf the parts, means rotatably supporting one of the parts, a radial arm fixed to one of the parts and having means at its outer end for connecting with a Vibrating body to produce vibratory rotation of the parts, and a radial arm iixed to the other of the parts adapted for connection with a vibration pickup.

5. An apparatus for producing electrical signals in response to the vibrations of a body which may move beyond the range of its vibratory motion, comprising a pair of relatively rotatable closely spaced cylindrical members, a thin film of Viscous liquid positioned between the members forming the only means for transmitting a force from one of the members to the other, said film of liquid permitting comparatively slow relative rotation of the members to correct misalignment, means rotatably supporting one of the members, a radial lever fixed to one of the members, means plvotally connected with the lever for attachment to a vibrating body for producing vibratory rotations of the member, a radial arm fixed to the other of the members, a pair of spring arms respectively contacting opposite surfaces of said arm to provide resilient resistance to rotation of said arm in either direction, and an electrical contact member adjacent one of said spring arms.

HORACE M. NORMAN,

REFERENCES CTED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 740,547 Fiske Oct. 6, 1903 1,338,122 Carlstedt Apr. 27, 1920 1,947,332 Christen Feb. 13, 1934 2,383,405 Merrill et al Aug. 21, 1945 FOREIGN PATENTS Number Country Date 61,504 Switzerland Sept. 20, 1912

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