US2084001A

US2084001A - Hydraulic shock absorber

Info

Publication number: US2084001A
Application number: US16076A
Authority: US
Inventors: John C Mcginnes
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-04-12
Filing date: 1935-04-12
Publication date: 1937-06-15
Anticipated expiration: 1954-06-15

Description

June 15, 1937. .1.-c. M GINNES HYDRAULIC SHOCK ABSORBER Filed April 12,- 1935 5 Sheets-Sheetl M w m n m H t M m 0 M7 4 1 a l. 6 0 0 a J w 7 m g a m J P w T L 6 a V .I 2 x 7 7// 7 x I June 15, 1937. J. c. MOGINNES 2,084,001. 7 HYDRAULIC SHOCK ABSORBER Filed April 12, 1935 5 Sheets-Sheet 2 l I Inventor 7 gz m 1 Allornep June 15, 1937. .1. c. McGlNNES HYDRAULIC S HOCK ABSORBER I 5 Sheets-Sheet 3 Filed April 12, less Inven [or 6'. M Q/mw A ltomey June. 15, 1937. J. c. M GINNES HYDRAULIC SHOCK ABSOR BER s Sheets-Sheef 4 Filed April 12, 1935 A Home}:

June 15, 1937. J. c. MCGINNES Filed April 12, 1935 5 Sheets-Sheet 5 /E/m 0. gm;

Patented June 15, 1937 HYDRAULIC SHOCK ABSORBER John C. McGinnes, South Williamsport, Pa.

Application April 12,

4 Claims.

This invention relates to a hydraulic shock absorber mainly designed for use on vehicles, the general object of the invention being to provide a shock absorber which can be manufactured to sell at low cost and one which can be easily applied to a vehicle, with means for enabling the movable member to have free travel for any predetermined position and amount of travel for each stroke of the piston or movable member,

one independent from the other.

This invention also consists in certain other features of construction and in the combination and arrangement of several parts, to be hereinafter fully described, illustrated in the accompanying drawings and specifically pointed out in the appended claims.

In describing the invention in detail, reference will be had to the accompanying drawings wherein like characters denote like orcorresponding parts throughout the several views, and in which:-

Figure 1 is a rear view of the device. Figure 2 is a section on the line 2-2 of Figure 1.

Figure 3 is a section on the line 3-3 of Figure 4.

Figure 4 is a section on the line 4-4 of Figure 3.

Figure 5 is a section on the line 5-5 of Figure 3.

on the line 8-8 of Figvalve housing of the device when used on the rear axle, this view showing a part in dotted lines.

Figure 13 is a section on the line l3l3 of Figure 12 this view being in a smaller scale than that of Figure 12.

Figure 14 is a fragmentary view showing a modified way of arranging the passages in the shaft and housing.

Figure 15 is a sectional view showing a modi- 1935, Serial No. 16,076

fication and with the piston moving in one direction.

Figure 16 is a sectional view of another modification and in position when the piston moves in an opposite direction.

Figure 17 is a fragmentary view of a modification showing how the grooves are arranged in the shaft.

Figure 18 is a fragmentary sectional view on the line Ill-l8 of Figure ll.

Figure 19 is a section on the line Iii-l9 of Figure 20 and showing a further modification.

Figure 20 is a section on the line 20-28 of Figure 19 but with the shaft omitted.

In these drawings the numeral l indicates a cylinder or casing having its rear end closed by a plate 2 which may be welded to the casing and this plate is formed with the valve housing or partition member 3 which divides the cylinder into an upper reservoir 4 and a pressure chamber 5. The piston 6 oscillates in the chamber 5 and is connected with the shaft '1, the shaft entering the cylinder through the enlarged central portion of the closed front end of the cylinder, this enlarged part terminating in a substantially cylindrical part 8 to which is connected a packing gland 9 for preventing leakage by the shaft. An arm or lever is adapted to be connected to the outer end of the shaft 1 and to be connected to the movable part of the vehicle which the shock absorber is to be used with.

The member 3 is formed with a centrally arranged substantially semi-circular recess into which the shaft extends and the lower edge of said member 3 slopes downwardly and outwardly as shown at 3 to provide stops for the piston 6, if the piston should happen to move so far as to engage the member 3.

At each end of the member 3 is a passage II) which connects the reservoir 4 with the chamber 5 and this passage is controlled by an upwardly closed valve ll held to its seat by a spring l2. As it will be understood this valve will permit fluid, such as oil, to flow from the reservoir into the chamber 5 but will prevent the oil from passing from the chamber back to the reservoir.

An elongated chamber I3 is formed in the top part of the member 3 and constitutes a fluid control chamber and a passage l4 co'nnects each end of this chamber [3 with the chamber 5 and a passage [5 connects each end of the chamber l3 with the chamber 5, this passage l5 being spaced outwardly from the passage l4 and is connected with the passage l4 by a port it. The upper end of each passage [5 is reduced to form a valve seat for a ball valve H, the two valves I! being held on their seat by a leaf spring l8 the central part of which passes under a rod l9 supported in the member 3. A cage or shell 20 is located in each passage I 3 and terminates at the point where the port i6 connects with the passage I4, that part of the passage l4 above the port I 6 forming a valve seat for a ball valve 2| which is pressed upwardly against the seat by 'a spring 22 in the cage. The lower end of the cage is reduced to form a valve seat for a ball valve 23 which closes downwardly and a pin 24 acts to hold the spring 62 and shell 23 in position as shown in Figure 7, this pin also acting to limit upward movement of the valve 23.

A pair of oppositely arranged diagonal passages 25 are formed in the shaft and have their lower ends in communication with the chamber 5 one on each side of the piston 6 and diagonally arranged passages 26 are formed in the member 3 and communicate with the control chamber l3 and when the piston 6 and shaft 1 are in certain positions these passages 26 will communicate with the passages 25 in the shaft so as to permit the flow of fluid from one part of the chamber 5 into the chamber l3 and from the chamber l3 into the other part of the chamber 5. The upper end of each passage 25 may be widened as shown at 25' to permit the fluid from a passage in the memher 3 to enter a passage 25, or vice versa, before and after the passages come into alignment.

Thus it will be seen that when the piston 6 is moving in one direction the valve I I opens to permit oil from the reservoir to enter that part of the chamber 5 at the trailing side of the piston and that the fluid compressed by the expanding side of the piston will flow through the passages l5 and I6 forcing the valve l1 off its seat and against the pressure of the spring l8 so that the fluid can enter the chamber l3 and the fluid displaced in the chamber l3 bythe incoming fluid will force the valve 2| off its seat and against the pressure of the spring 22, at the opposite side of the member 3 so that this fluid will enter the chamber 5 at the trailing side of the piston through the port I 6 and passage I5. Some of the fluid compressed by the piston will flow through a passage 25 and a passage 26, when these passages are in communication with each other and some of the fluid in the chamber l3 will flow into the chamber 5 at the trailing side of the piston through the other set of

passages

26 and 25. By varying the lengths of the widened part 25' at the upper ends of the passages 25 the first part of the movement of the piston, in either direction, will take place without resistance on the part of the fluid and the amount of this movement can be controlled by the width of said parts '25. Thus the free movement of the piston can be set for a predetermined distance and the piston returned to its normal position with resistance of which the maximum is governed by the relief valve I1.

The instrument may be altered for use on the rear of the car from the one used on the front by adding the passage 26' (see Figs. 12 and 13), which acts the same as the passage 26 in communicating with the passage 25. Its purpose is for permitting less resistance of the instrument for the first short distance of piston travel when returning to normal position, when the frame of the car is close to the axle. An instrument provided with this feature will permit the car to run at high speed on rough roads with the car loaded,

with less danger of the car frame striking the axle. It permits the frame to move away from the axle faster and the car springs will be ready sooner for the next bump in the road. More provision for preventing jolts or the like is the distance of free piston travel, when leaving normal position, permitted by the widened part 25', ending a short distance before the car frame approaches the axle, permitting the instrument to have resistance a short distance before the jolt can take place.

In Figure 14 is shown an arrangement of valve passages in which the communicating orifices 21 and 21' never totally align because the one 21 in the shaft 7 which passes the other 21' in the member 3 is offset in its line of travel to the other.

A manufacturing advantage is that the instrument is both right and left handed, except for the small passage 26. It is suitable for both front and rear of the car, except for the amount of free piston travel when leaving normal position, as determined by the length of the widened part 25', which is more for the rear of the car, and the addition of the passage 26 for the front.

The instrument is thought of primarily as one that will permit car spring action and resist reaction, which makes a gliding ride out of what would otherwise be a jolting one.

All moving parts such as bearings are lubricated with oil, or whatever is used as a shock absorber medium, under pressure, due to pressure in the compression chamber 5. This oil may have a small quantity of pulverized graphite mixed with the oil which will more or less coat the hearing surfaces, and form a smooth bearing surface of graphite, resisting wear of the instrument.

Normal position may be a position at which the piston rests when the car is empty, also a position at which the piston leaves without resistance and returns to with resistance.

In order to prevent any fluid pressure reaching the gland 9 surrounding the shaft 7 I provide a groove 29 in the casing part 8 which communicates with a passage 30 connecting the groove 29 with the reservoir 4 so ing fluid will pass back to the reservoir. I also provide a passage 3! in the member 3 which connects the reservoir with the space at the rear end of the shaft, see Figure 2, so that air can escape from the compression chamber to the reservoir.

It will thus be forced out from Way around the at the rear of is being filled by way of this passage. The air is replaced with oil by the movement of the piston sucking in oil and forcing the air out around the shaft inasmuch as the shaft has only a moving flt in the partition member.

Figure 11 shows a modification of such means in which the shaft is provided with a longitudinal extending passage 32 communicating with the openings 33 in the shaft 7, and said openings are in communication with the groove 30 in seen that air which is being the compression chamber by shaft and reaches the pocket the shaft when the instrument the member 8 so that the escaping liquid or air at the rear of the shaft can return to the reservoir from the groove 38 through the

passages

33 and 32 to the rear end of the shaft and then passed through the passage 3| to the reservoir.

Tapered pins 34 are driven into tapered recesses at the ends of the member 3 and the that the escap with oil escapes to the reservoir adjacent parts of the cylinder I, these pins acting as keys to stifien the device and prevent liquid from escaping from the compression chamher 5 to the reservoir These pins are driven into place so as to make them fit tightly and welded where exposed to the exterior of the instrument.

Small saw cuts 35 extend from the ends of the chamber it in the member 3 at points adjacent the pins 34, as shown in Figure 3, these cuts acting to collect liquid which might otherwise escape, due to pressure from the compression chamber to the reservoir, and return it by way of the control chamber.

The oil or the like is placed in the reservoir 4 through an opening closed by a plug 36 and recesses 31 are formed inv the front and trailing sides of the piston for receiving the projecting parts of the cages and I prefer to form the gland 9 of the packing material 38 pressed upon by the washer 39 which is under compression by the springs 43 which are preferably of the shape shown in Figures 9 and 10.

The instrument has free piston travel for any predetermined position and amount of travel for each stroke of the piston, one independent of the other and this is secured by the arrangement and cooperation of the

valve forming passages

25, 25 and 26 and the check valves 25. In 9 other words, the device can be designed, if desired, for the piston to travel freely, or with resistance, for any part of each stroke.

The diameter of each ball valve ll plus the thickness of the spring I8 is greater than the 5 height of the control chamber and this prevents the ball from getting away from the orifice which forms its seat as the bottom of the ball cannot get as high as the top of the orifice in which it is set.

0 As it will be seen the spring l8 has each end resting on a valve ball I? and the middle resting on the pin l9. It is wider at the middle 50 as to make it form a true arc when compressed, resulting in the spring being very durable as it bends equally throughout its length beball seats itself in the tween the balls. If the spring should have too much resistance, a little material may be taken off the tapered edge, reducing its width, consequently reducing its resistance. If the pin IS 0 is shifted off center, closer to one of the balls than the other and the spring is made widest at that point, one relief valve will have a greater resistance than the other, resulting in one direction of piston travel having a greater maximum resistance than the other. The spring has no holes nor anything thatwill weaken it nor make it expensive to make. It can be compressed only a short distance which protects it against breakage. Although it is not securely O fastened with anything, it cannot become dislocated when the instrument is assembled. Each check valve 2! when opening travels about then seats itself in the shell 20. In doing so it compresses the valve spring 22. The ball is a free-moving fit in the hole containing the ball and shell, keeping the ball in alignment with the shell. The valve will usually open speedily. The liquid naturally filling the shell cannot escape from the shell, only around the ball as the shell, because the orifice in the bottom of the shell is closed with the small ball 23. The result is, the slam of the ball is cushioned with the liquid as the ball seats itself in the shell because it closes the opening in the 5 top of the shell in doing so. This prevents pounding of the ball which compresses a spring which has only a small amount of resistance, eliminating noise and unnecessary wear. When the valve 2! closes, the ball in the bottom of the shell opens the orifice and permits liquid to flow into the shell, consequently permitting the spring to lift the ball from the shell without a tendency to resist it with a vacuum and per mitting the ball to act faster than the action of the shock absorber. In other words, the spring closes the valve before the fluid forces the valve to closed position, due to piston action. The shell is to govern the displacement of the ball, protecting the life of the spring. The liquid in the shell prevents the pounding of the ball on the shell when the valve opens, preventing destruction of the shell. The check valve in the bottom of the shell is to eliminate a suction in the shell when the ball leaves the shell, permitting the spring to close the valve without any resistance due to vacuum. A more or less deli cate spring is to eliminate pressure in the control chamber, which prevents liquid from escaping into the reservoir.

In the modification shown in Figure 15 the control chamber is eliminated and angle passages iii! are formed in the abutment member 5i, each passage 5% having an enlarged end opening into the compression chamber, said enlarged part has a ball valve 52 therein held in place by a pin 53 and the shaft 1 is provided with the passages 5d arranged as shown and the upper end of each passage is widened as shown at 54'. Thus the fluid compressed by the piston will pass through a passage 56 into a passage 56, when said passages 5i! and 56 come into communication with each other during movement of the shaft 1' and then said fluid will pass by the valve 52 into that part of the compression chamber which is at the trailing side of the piston and of course, when the piston moves in an opposite direction the fluid will discharge from the other passage 50. Instead of having the check valve in the passages 59 they may be placed in the passages 54" as shown in Figure 16.

Figures 17 and. 18 show a modification somewhat like that shown in Figure 15 except that grooves are formed in the shaft 1" for the entrance of the fluid, the upper ends of these grooves being provided with right angle extensions 55" which communicate with the passages 56 in the valve housing 5'4, when the piston has moved to a certain position.

Figures 19 and 20 show a somewhat similar construction but the valves 53 are located in the passages so in the shaft and the grooves are formed in the housing as shown at fill. Of course, these forms of the invention will be provided with the passages for connecting the reservoir with the compression chamber and the upwardly closing valve in said passages, these parts not being shown.

Figures 15 to 20 show various arrangements of passages for permitting the flow of fluid and preventing the fiow of fluid for the same direction of piston travel, it being understood that fluid cannot pass from in front of the piston until the piston reaches a position Where the passages in the shaft and the abutment member are in communication, and then the fluid can pass from in front of the piston, back into the compression chamber in rear of the piston. Then when the passages are placed out of communication with each other by movement of the piston, the fluid is trapped in the chamber in front of the piston.

It is thought from the foregoing description that the advantages and novel features of the invention will be readily apparent.

It is to be understood that changes may be made in the construction and in the combination and arrangement of the several parts, provided that such changes fall within the scope of the appended claims.

What is claimed is:

1. A device of the class described comprising a cylinder, a partition member dividing the cylinder into a reservoir and a compression chamber, a shaft extending into the compression chamber and having a bearing in a part of the partition member, an oscillating piston connected with the shaft and located in the compression chamber, said partition member having a control chamber therein having its ends in communication with the compression chamber at opposite sides of the piston, valve means for controlling such communication, said shaft having passages therein opening out into the compression chamber at opposite sides of the piston and said partition member having conduits therein for communicating with the passages in the shaft. when the shaft is in certain positions, said conduits communicating with the control chamber and valve controlled means for connecting the reservoir with the compression chamber at each side of the piston.

2. A device of the class described comprising a cylinder, a partition member in the cylinder dividing the same into an upper reservoir and a lower compression chamber, a shaft extending into the compression chamber, an oscillating piston connected with the shaft and located in the compression chamber, said partition member having passages connecting the reservoir with the compression chamber at both sides of the piston, upwardly closing spring-pressed valves controlling said passages, an elongated control chamber in the partition member, passages connecting the ends of the control chamber with the compression chamber at the sides of the piston, upwardly opening control valves for some of the passages, spring means for holding said control valves in closing position, downwardly opening check valves for the other passages, spring means for holding said check valves in closed position, the shaft having diagonal arranged passages therein opening out into the compression chamber one on each side of the piston, said partition member having passages therein connecting the passages in the shaft, when the shaft is in a certain position with the control chamber.

3. A device of the class described comprising a cylinder, a partition member therein dividing th same into a reservoir and a compression chamber, a shaft extending into the chamber, a piston connected with the shaft and oscillating in the compression chamber, said shaft having conduits opening out into the compression chamber one at each side of the piston, said partition member having conduits therein opening out into the compression chamber one on each side of the piston, the last mentioned conduits communicating with the conduits of the shaft when the shaft is in certain positions and check valves for controlling the fiow of fluid through said conduits, said partition member having passages connecting the reservoir with the compression chamber one on each side of the piston and spring-pressed valves controlling said passages and closing toward the reservoir.

i. A shock absorber comprising a pressure chamber, a piston movable in said chamber, means for supplying a liquid to said chamber on opposite sides of said piston, a passage in the shock absorber leading from one side of the piston to the other, said passage being open to permit the flow of liquid therethrough only according to certain positions of the piston, said passage also being closed to prevent the flow of liquid therethrough according to certain other positions of the piston, said passage having therein a check valve mechanism comprising two parts one stationary and the other adapted to move to a limited extent, said two parts forming a, closed hollow chamber when the check valve is in one position and an open hollow chamber when the check valve is in another position, said stationary part having a check valve in the opposite end from the end adjacent the movable part to permit liquid to flow into but not from said hollow chamber, said hollow chamber having a spring therein which yieldingly presses said movable part toward its valve seat, said two parts being inserted in a round hole in which they closely fit, said round hole having a portion of its length at its inner end reduced in diameter to form a valve seat for said movable part, said round hole portion which is reduced in diameter forming part of said passage which leads from one side of the piston to the other.

JOHN C. MCGINNES.