US2016745A - Timing gear silencer - Google Patents

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L.v B. HUTHSHNG TIMING GEAR SILENCER Filed March 13, 1955 Y Patented Oct. 8, 1935 UNITED STATES PATENT. OFFICE vTIR/[ING GEAR SILENCER Leo B. Huthsing,` Los Angeles, Calif. l Application March 13, 193,5, Serial No. 10,954 12 Claims. (o1. 18s-s3) My invention relates toy a device which has a slight retarding or braking action on one of the timing gears such as used in automobile internal combustion engines.

In such gears it is usual to have a fiber gear or the equivalent operating with a metal gear. When these become worn the wear being principally in the ber gear, a back lash action is de" veloped which creates a noise. It is usual to have the ber gear on the cam shaft and hence in the operation of this shaft the cams actuating the tappets of the valves, the back lash action is developed.

A further object and feature of my invention is the employment of a friction shoe which is mounted on theV timing gear casing and which shoe is pressed ,by a spring against the flat rim of one of the timing gears, the practice being usually to press this against the fiber gear. Therefore the shoe creates a slight frictional resistance against the flat face of the ber gear and thus reduces the backlash action, causing a more or lessconstant driving pressure between the teeth of the two meshing gears.

j Another object and feature of my invention is connecting an oil pipe with an oil feed through the shoe to the fiat rim of the fiber timing gear. This not only lubricates the contact faces between the shoe and the gear but also provides 301 additional oil for lubricating the timing gears.

A further detailed feature of my invention is constructing the shoe in the form of a cup with a disk face, the cup of the shoe fitting over a stationary cup which is formed integral with a 3,51 tubular threaded'stern. The stem is threaded through a threaded hole in the timing gear casing until the stationary cup seats on the inside face of the casing. With this assembly I use a coil compression spring betweenthe two oups which thrusts the shoe with a resilient pressure against the flat rim of the gear. The lubrication is provided for by connecting the oil pipe from the oiling system of the engine to the outer end of the tubular stem. The oil thus flows through the 415W stem, filling the two cups and flowing through a perforation inthe shoe.

Another feature of my invention relates to the assembling of the device on the gear casing, in that I pass a long stemmed screw through the tubular stem, the Xed cup, the space having the spring, and thread this into the shoe; the head of the screw engaging the outer end of the stem. 'I'his holds the spring compressed and the two cups in assembly while the device is being fitted 5.5: in the timing gear casing. vWith some types of automobiles it is necessary' to tilt the casing for purposes of assembly. The screw must be removed before the oil pipe can b e connected to the tubular stem.

My invention is illustrated in connection with 5 the accompanying drawing, in which,

Fig. 1 isa side elevation of an engine partly broken away, to show the position of the timing gears and my silencer in assembled position.

Fig. 2 is a transverse section on the line 2-2 10 y of Fig. 1 in the direction of the arrows.

- Fig. 3 is a partial longitudinal section through the silencer assembly and may be considered as taken on the line 3-3 of Fig. 2 in the direction of the arrows. 15

, In the drawing, a cam shaft is indicated by the numeral Il and this is driven by usually a liber driven gear l2, which driven gear meshes with a driving gear I3 which is usually of metal. Such ldriving gear is usually mounted on a crank shaft 20 I4 or similar shaft driven in synchronism with the movement of the engine crank. The fiber timing gear l2 usually has an annular rim I5 which extends outwardly at the sides from the main body portion I6, there being a circular re- 25 cess I1. The teeth I8 extend outwardly from the rim and the rim usually has a flat face I9, this face being in a plane at rightangles to the axis of the cam shaft or the shaft on which such gear ismounted. v Y

The timing gears are enclosed by a gear casing 2i) this being secured to the engine block and crank case 2|, by bolts 22 and in certain types of engines there is a threaded perforation 23 in the gear casing, butwhere there is no such per- 35 foration this may be drilled and tapped in the proper position relative to the rim face I9 of the fiber timing gear.

My silencer assembly illustratedin section in Fig. 3, utilizes a tubular stem 25 exteriorly thread- 40 edras indicated at 2B and having a small bore passage 2l. On the end of this stem there is an inner circular cup 28 which has a base 29 -and a circular rim 30. The friction Shoe 3l has a basev 32with a circular or disk-like bearing sur- 45 face 33. This disk of the shoe is provided with a perforation 34, such perforation being at least partly threaded. The shoe has'an annular flange 35 and thus forms a cup, the rim .Se of the fixed cup and the flange 35 of the cup forming 50 the full overlap. A coil compression spring 36 which is preferably of the combined spiral and helical type, thus forming a cone-shaped spring, is fittedV between the cup forming the shoe and the cup attached to the stem. In order to secure these elements together for assembly purposes, I utilize a long stemmed screw 31 which passes through the bore 21 of the stem and is threaded into the threaded perforation 34 of the base of the shoe. rIhis screw has a head 38 which bears against the outer end of the stem.

The manner of assembly is as follows: On account of the area of the shoe being much larger than the area of the perforation 23 in the gear casing, it is necessary in most types of engines to which my invention may be applied, to loosen the bolts 22 and at least partly tilt the casing outwardly at the top. 'I'his allows inserting of the tubular stem 25 from inside the casing and it is screwed in by hand until the base 29 of the cup 28 seats on the inside surface 39 of the gear casing 20. During this assembly the two cups are held in clamped relationy by the bolt 31 and there is no chance of the bearing shoe being forced out of the assembled position by the compression spring 36. When the housing or casing of the gears is again firmly secured to the engine block and the crank case, the screw 38 may be removed. A lock nut 40 is then threaded on the outer end of the stem and holds the stem from an unscrewing rotation in the perforation 23. When the bolt 31 is removedthe spring forces the shoe 3l longitudinally as regards the axis of the stem and brings the flat face of the shoe into contact with the flat annular surface I9 of the rim of the fiber gear.

It is preferable to assemble the device and locate the perforation 23 so that the axial centerl of the shoe is approximately midway between the inner and outer periphery of the flat surface I9 of the rim of the gear. If desired, this bolt 31 may be removed before the bolts 22 clamping the gear casing in place are screwed down tight.

In order to lubricate the silencer, I provide an oil pipe 45 which at one end 46 is connected to the engine and to the oiling pressure system thereof. The other end is attached by a threaded gland or nut 41 to the outer threaded .end of the stem 25. To assure that the bolt 31 will not inadvertently be left in place, this bolt must be removed before the oil pipe 45 can be attached to the stem.

The manner of operation and functioning of my invention is as follows: It will be obvious that the shoe 3l is pressed by the compression spring 35 against the flat annular face of the fiber timing gear. This shoe is prevented from displacement by the intertting of the rim 3l) of the flange 35 of the fixed cup structure 28 and the movable cup structure of the shoe 3l. However, there is no resistance to the rotation of this shoe on its axis should there be any force rotating it, but apparently it does not rotate on its axis. The shoe therefore gives a large surface which exerts a pressure sidewise on the fiat annular surface of the gear, and hence as the gear rotates, there is a frictional resistance to such rotation. This resistance is sufficient to cause the teeth of the meshing gears to always have a pressure relation and hence eliminates the backlash and thus the clash and noise of the timing gears.

The iiow of lubricating oil has an important function in my invention. This oil fills the hollow chamber containing the spring 36, the fit of the rim 30 and flange 35 being such that but little oil escapes at this joint and practically all of the oil is discharged through the perforation 34 in the base of the shoe. This oil comes directly in contact with the fiat annular face of the gear and hence lubricates the bearing surface of the .shoe on the gear. 'I'his reduces the friction, but not sufiiciently to allow the gears to have a backlash and become noisy. The oil also keeps the shoe and the gear cool and the spring 36 cool so these will not become hot through frictional 5 heat. Moreover, the fiow of oil thoroughly lubricates the timing gears, thus causing an improved power transmission between the metal and the driven ber gear.

Various changes may be made inthe details 1o of construction without departing from the spirit or scope of the invention as dened by the appended claims.

I claim:

l 1. In a device as described, the combination of 15 an engine having a rotating timing gear, a casing for said gear having a perforation, a friction shoe, a supporting device for said shoe extending through the perforation, and a spring engaging the shoe to press the shoe into contact witha 20 smooth surface of the gear.

2. In a device as claimed in claim 1, means to inject oil through the perforation and the casing to lubricate the said shoe and the said smooth surfacerof the gear. 25 3. In a device as described, the combination of a rotatable timing gear having a smooth annular surface, a casing for the gear having a perforation, a stem extending through the perforation,

a shoe, a spring developing a pressure between 3C` the stem and the shoe, to press the shoe against the said surface of the gear, whereby a frictional resistance to the rotation of the gear is developed.

4v. In a device as claimed in claim 3, the stem being hollow and the shoe having a perforation 35 and an oil connection outside the casing to the stern for injecting oil to the Contact surfaces ofi the shoe and the gear. Y

5. In a device as described, the combination of an engine having a rotating timing gear with a 40 smooth annular surface, a casing for the gear having a perforation, a stem threaded in said perforation, a shoe having a circularface, a spring between the shoe and a portion of the stem to press the face of the shoe against the 45v said annular surface of the gear and thereby cre. ate a resistance to the rotation of the gear.

6. In a device as claimed in claim 5, the stem being tubular, the shoe having a central perforation, an interconnection between the shoe and 50 part of the stem to restrict the fio-w of oil through the perforation of the shoe, and an oil pipe secured to the end of the stem projecting on the outside of the casing.

'1. In a device as described, the combination of 55 an engine having a rotating timing gear with a smooth annular surface, a casing for the gear having a perforation, a stem extending through the perforation and having a cup-like head on the inside, a cup-like shoe interfltted with the cup 60 of the stem, the said shoe having a smooth surface to engage the said surface of the gear, a spring between the said cups, whereby a friction resistance is developed betweenthe shoe and the gear.

8. In a device, as claimed in claim '7, the stem and the cup attached thereto having a central bore, the shoe having a perforation and an oil pipe connected to the end of the stem outside of the casing.

9. In a device as described, the combination of an engine having a timing gear with a smooth annular surface in a plane at right angles to the axis of the gear, a casing for the gear having a perforation, a stem extending through the perfo- 'l5 ration, a cup-like head on the stem having a bearing on the inside of the casing, the said cup having an annular rim, a shoe having a disk with a friction surface and an annular flange intertting with the rim of the cup, a coil spring between the cup and the shoe to press the shoe into contact with the annular` surface of the gear.

10. In a device as claimed in claim 9, the stem and the cup connected thereto having a central bore, the cup having a central perforation, the t formed by the rim and the fiange restricting ow of oil and an oil pipe connected to the stern projecting outside of the casing.

11. In a device as claimed in claim 9 the stem and the cup secured thereto having a central bore,

the shoe having a threaded socket, a bolt extending through the bore and threaded in the socket and having a head engaging the outside of the stern, the said bolt holding the stem, cup and shoe and the spring assembled for connection to the perforation in the casing.

12. In a device as described, the combination of an engine having a rotating timing gear, a casing for the gear, a shoe resiliently mounted on the casing and bearing against a portion of the gear adapted to create a frictional resistance to the rotation of the gear, and means to inject oil between the shoe and the gear to lubricate their contact surfaces.

LEO B. HUTHSING. 15

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