US3631884A

US3631884A - Compensator for temperature-caused length change

Info

Publication number: US3631884A
Application number: US8842A
Authority: US
Inventors: Carl V Von Linsowe
Original assignee: Individual
Current assignee: VON LINSOWE DOROTHY M
Priority date: 1970-02-05
Filing date: 1970-02-05
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

An elongated structure whose effective length is substantially independent of changes in ambient temperature. The structure includes between its ends an elongated portion whose length varies directly with changes in ambient temperature operatively connected end-to-end to a plunger and cylinder assembly whose effective length varies inversely with changes in ambient temperature. Positive-temperature-coefficient fluid is provided in a chamber in the cylinder whereby expansion of this fluid shortens the assembly and contraction of the fluid lengthens the assembly.

Description

United States Patent [72] Inventor CarlV.VonL1nsowe San Jose, Calif. [21] Appl. No. 8,842 [22] Filed Feb. 5, 1970 [45] Patented Jan.4, 1972 [73] Assignee JohnT. Page Portland, Oreg. apart interest [54] COMPENSATOR FOR TEMPERATURE-CAUSED LENGTH CHANGE 6 Claims, 2 Drawing Figs.

[52] U.S.(l 137/344, 239/212 [51] lnt.(l BOSb 9/02, E0 1 h 3/02 [50] Field of Search 137/344; 239/212, 213, 397.5; 73/3682 [56] References Cited UNITED STATES PATENTS 2,183,596 12/1939 Trinks 23 9/3975 p 2,800,364 7/1957 Dick et al. 239/212 X 3,213,918 10/1965 Rudzki et al 239/397.5 X 3,233,459 2/1966 Gleason et al. 73/3682 X 3,259,319 7/1966 Wallace 239/212 X 3,282,103 11/1966 Steele.... 73/3682 X 3,365,946 1/1968 Hall 73/3682 X 3,491,784 l/1970 Lilly 137/815 3,519,206 7/1970 Leaders 239/213 Primary ExaminerSamuel Scott Attorney-Kolisch & Hartwell ABSTRACT: An elongated structure whose effective length is substantially independent of changes in ambient temperature. The structure includes between its ends an elongated portion whose length varies directly with changes in ambient temperature operatively connected end-to-end to a plunger and cylinder assembly whose effective length varies inversely with changes in ambient temperature. Positive-temperature-coefficient fluid is provided in a chamber in the cylinder whereby expansion of this fluid shortens the assembly and contraction of the fluid lengthens the assembly.

mama m 4 mrz ma V. mv awake BY KM q H ML COMPENSATOR FOR TEMPERATURE-CAUSED LENGTH CHANGE BACKGROUND OF THE INVENTION This invention pertains to length-change compensation. More particularly, it pertains to a compensator which may be incorporated with an elongated member whose length changes directly with changes in ambient temperature to produce a structure having an overall length that is substantially independent of ambient temperature. A preferred embodiment of the invention is described herein in conjunction with parts in a mobile irrigator wherein it has been found to have particular utility.

There are many applications where it is desirable to use a structure whose dimensions remain substantially constant despite changes in ambient temperature. This is particularly important where a structure has one or more relatively large dimensions (for example, length), and is interconnected with other structures. In such an assembly, a temperatureproduced dimension change in a structure might well result in overstressing and damage to different parts in the assembly.

As an illustration, in a mobile irrigator having an elongated articulated multiple-section frame, with such supported at different points for travel over the ground in a direction substantially normal to the longitudinal axis of the frame, length-stability in the longitudinal structures of the frame is a very important consideration. The frame in such an irrigator might, for example, be as much as a quarter mile or so. With this the case, any substantial length changes that occur in the frames longitudinal structures may produce damaging side loading on the ground-traveling supports provided for the frame.

SUMMARY OF THE INVENTION Therefore, a general object of the present invention is to provide a novel compensator which may be incorporated with an elongated member whose length changes directly with changes in ambient temperature to produce a length-stable structure having an overall length that is substantially independent of ambient temperature.

Another object of the invention is to provide such a compensator which when incorporated in the type of structure mentioned, is capable of transmitting an axial load.

Still a further object of the invention is to provide a compensator of the type generally indicated which is reliable and simple in construction, and which may readily be incorporated in many different types of structures. 1

Thus, and according to a preferred embodiment of the invention, a compensator is proposed which takes the form of a cylinder and plunger assembly, wherein there is a chamber defined between the plunger and cylinder containing positivetemperature-coefficient liquid. With an increase in ambient temperature, the liquid in the chamber expands, and shifts the plunger and cylinder relative to one another to shorten the overall effective length of the assembly. The reverse action takes place with a decrease in ambient temperature. The compensator is mounted substantially in longitudinal alignment with a structural member whose length varies directly with changes in ambient temperature to produce an overall structure whose length is substantially independent of temperature.

The specific length change which occurs in the compensator for a given temperature change depends upon the dimensions of the plunger and the cylinder. Thus, a compensator may be provided to take care of many different types of situations.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages attained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a simplified front elevation illustrating portions of an elongated articulated mobile irrigator including longitudinal frame structures incorporating the present invention; and

FIG. 2 is an enlarged view illustrating a compensator constructed according to the invention mounted endo relative to a longitudinal truss in the irrigator of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Turning now to the drawings, and referring first to FIG. I, indicated generally at 10 is an elongated articulated mobile irrigator which extends a considerable distance over the ground, shown at 12. The irrigator includes a multiple-section frame made up of two spaced substantially parallel rows of longitudinal structures, such as the row shown in FIG. I containing longitudinal structures 14. Extending transversely between the two rows of longitudinal structures, between points adjacent different sets of confronting ends of the longitudinal structures, are transverse structures (not shown) which are similar in construction to the longitudinal structures. Adjacent sets of ends of longitudinal and transverse structures are interconnected through suitable articulation means, such as those indicated generally by circular outlines at 16, which accommodate a certain amount of relative angular movement between the structures to take care of unevenness in the ground. The longitudinal and transverse structures in the frame are supported above the ground, and for movement thereover, through upright legs 18, and wheels 20 which are carried adjacent the lower ends of the legs.

In the irrigator illustrated, the longitudinal structures are about 120 feet long. The transverse structures which are concealed behind articulation means 16 are about 90 feet long. Legs 18 support the longitudinal and transverse structures about l0 feet above the ground. The overall length of irrigator 10, indicated generally at A in FIG. I, is about one-quarter mile.

The irrigator is propelled over the ground, generally in a direction extending normally out of the plane of FIG. 1, by power drive means including one or more traction units, such as traction unit 22, which is carried adjacent the base of one of legs 18. The irrigator typically travels at a speed of about 1 mile per hour.

As will be more fully explained, each longitudinal structure in the frame of the irrigator includes an elongated rigid truss portion 24, and a compensator, or compensator means, 26. A compensator is mounted on and disposed in substantially longitudinal alignment with its associated truss portion. The truss portions, or trusses, in the longitudinal structures are employed to carry a suitable water-distribution system including conventional sprinkler devices such as those shown at 28.

Referring now to FIG. 2, which shows in somewhat greater detail the construction of a longitudinal structure in the frame of the irrigator, truss 24 includes an elongated central framework represented by dash-dot block 30. Joined to and extending axially from opposite ends of the central framework are hollow rectangular end members 32, 34. The central framework in the truss is represented herein by a dash-dot block for the reason that details of its construction form no part of the invention, and may have any one of a number of different configurations. One type of truss which may be used is described in detail in US Pat. No. 3,562,994, issued to me on Feb. l6, I971, entitled Truss."

At a given ambient temperature, for example 70 F., truss 24 has a length measured between the outer ends of members 32, 34 indicated at T,. On the ambient temperature increasing to, say, F., the truss lengthens (through length changes in its parts) to a length indicated at T The amount which the truss lengthens, of course, depends upon the sizes of its parts, and upon the particular increase in ambient temperature which occurs. Similarly, the truss shortens with a decrease in ambient temperature. Thus, the length of the truss changes directly with changes in ambient temperature.

To prevent such a temperature-produced length change from overstressing and damaging parts in the irrigators framework, compensator 26, constructed and mounted according to the invention, is provided. In general terms, compensator 26 comprises cylinder and plunger parts 36, 38,

respectively. In the embodiment illustrated, cylinder 36 is formed from an elongated tube 40 provided with axially spaced ports 42 closed off by plugs 44 which are screwed into the ports. Joined to the left end of tube 40 in FIG. 2 is a circular plate 46 having a central bore 46a. Joined to the right face of plate 46 is a tubular collar 48. Fastened to the right end of tube 40 is a circular plate 50 having a central bore 50a.

The cylinder is secured to truss member 34 through a mounting plate 52. Plate 52 is suitably joined to plate 46, and includes a central bore 52a, communicating with bore 46a. Lugs 56 joined to the left face of plate 52 extend into member 34 as shown and are secured rigidly thereto through fasteners 58. With such a mounting, he cylinder is disposed with its longitudinal axis substantially in line with the axis of truss 24, and is adapted tomove as a unit with the truss. I

Plunger 38 includes a rod 58 which extends slidably through bore 50a. The left end of the rod joins with a head 60 of larger outside diameter than the rod. A recess 59 provided in the left end of head 60 in FIG. 2 receives one end of a spring, or bias means, 62. The other end of the spring acts against the right face of plate 46, with collar 48 acting as a retainer for this end of the spring. Spring 62 is under compression, and tends to shift the plunger to the right in FIG. 2 relative to the cylinder. The outside of rod 58 is sealed to the inside of bore 50a through a seal 64 which is mounted on plate 50. The outside of head 60 is sealed to the inside of tube 40 through a 'seal 66 mounted on a ring 68 which is suitably secured to the inside of tube 40 at the location shown. The right end of rod 58 connects with an articulation means 16 through a mounting plate 70.

'Indicated generally at 72 is a chamber defined between the cylinder and plunger which is entirely filled with a suitable positive-temperature-coefficient liquid, such as methyl alcohol.

With an ambient temperature of about 70 F., the plunger and cylinder occupy the relative positions shown therefor in solid outline in FIG. 2. With such the case, the organization including compensator 26 and plate 52 has an effective length indicated at C,. On the ambient temperature increasing to about 85 F., the liquid in chamber 72 expands and acts against face 61 on head 60 to contract the compensator. In particular, with such a temperature increase, the compensator decreases in effective length an amount substantially equal to the increase in length resulting (from the same temperature increase) in truss 24. Thus, at the higher ambient temperature mentioned, the length of the organization including compensator 26 and plate 52 is indicated at C curring in the ambient temperature. In this case, the length of 1 the truss decreases and the length compensator 26 increases (by substantially the same amounts). The increase in length in the compensator results from contraction of the fluid captured in chamber 72, and from the action of spring 62.

The invention thus provides novel means for providing an elongated structure whose length is substantially independent of changes in temperature. With a compensator such as compensator26 employed, axial loads may readily be transmitted therethrough. The size of such a load is determined by the stiffness of the spring used corresponding to spring 62.

Ports 42 are used conveniently to provide access for filling chamber 72 with fluid.

The invention offers a considerable advantage in an organization, such as the frame in irrigator 10, where uncontrolled length changes in parts might add up and cause severe internal overstressing and damage. The particular length change which occurs in a compensator due to a given change in ambient temperature is a matter of choice, depending upon the relative sizing of the parts in the plunger and cylinder.

While an embodiment of the invention has been described herein, it is appreciated that variations and modifications may be made without departing from the spirit of the invention.

Iclaim:

1. An elongated mobile instrumentality comprising at least a pair of longitudinal structures disposed substantially end-to-end,

articulation means operatively interconnecting and permitting relative movement between said structures,

and at least a pair of spaced-apart ground-traveling supports supporting said structures for movement over the ground to act on said parts in a manner producing relative movement therebetween which increases the distance between said outer ends under all circumstances with a temperature decrease, and which decreases such distance under all circumstances with a temperature increase; and

means operatively connecting said portion and said compensator means substantially in longitudinal alignment, whereby on a change occurring in the ambient temperature, the resulting length change in said compensator means compensates for the resulting length change in said portion, and the overall length of said structure remains substantially constant.

2. In an elongated structure the combination comprising:

an elongated portion whose length changes directly with changes in ambient temperature;

elongated compensator means including a pair of elongated relatively reciprocable interconnected parts having spaced-apart relatively movable outer ends which are exposed, biasing means operatively interposed between and acting on said parts urging the same under all circumstances to move relative to one another in a direction tending to increase the distance between said outer ends, and means containing a captive body of positive-temperaturecoefiicient liquid, with such liquid held in a position effective in a direction substantially normal to the structures longitudinal axes,

said longitudinal structures each comprising between its ends an elongated portion whose length changes directly with changes in ambient temperature, and elongated compensator means disposed substantially in longitudinal alignment with said portion whose length changes inversely with changes in ambient temperature in a manner whereby the overall length of the structure remains substantially constant.

3. The structure of claim 2, wherein said bias means comprises a spring under compression.

4. The structure of claim 2, wherein one of said parts comprises a cylinder, and the other part comprises a plunger slidably mounted on said cylinder.

5. The structure of claim 4, wherein said means containing said liquid comprises a chamber defined between said cylinder and said plunger.

6. A length-change compensator for use in combination with an elongated member whose length changes directly with changes in ambient temperatures to produce a structure having an overall length which is substantially independent of temperatures comprising a pair of elongated relatively reciprocable interconnected parts having spaced-apart relatively movable outer ends which are interposed,

biasing means operatively interposed between and acting on said parts urging the same under all circumstances to move relative to one another in a direction tending to increase the distance between said outer ends, and

means containing a captive body of positive-temperaturecoefficient liquid, with such liquid held in a position effective to act on said parts in a manner producing relative movement therebetween which increases the distance between said outer ends under all circumstances with a temperature decrease, and which decreases such distance under all circumstances with a temperature increase.

Claims

1. An elongated mobile instrumentality comprising at least a pair of longitudinal structures disposed substantially end-to-end, articulation means operatively interconnecting and permitting relative movement between said structures, and at least a pair of spaced-apart ground-traveling supports supporting said structures for movement over the ground to act on said parts in a manner producing relative movement therebetween which increases the distance between said outer ends under all circumstances with a temperature decrease, and which decreases such distance under all circumstances with a temperature increase; and means operatively connecting said portion and said compensator means substantially in longitudinal alignment, whereby on a change occurring in the ambient temperature, the resulting length change in said compensator means compensates for the resulting length change in said portion, and the overall length of said structure remains substantially constant.

2. In an elongated structure the combination comprising: an elongated portion whose length changes directly with changes in ambient temperature; elongated compensator means including a pair of elongated relatively reciprocable interconnected parts having spaced-apart relatively movable outer ends which are exposed, biasing means operatively interposed between and acting on said parts urging the same under all circumstances to move relative to one another in a direction tending to increase the distance between said outer ends, and means containing a captive body of positive-temperature-coefficient liquid, with such liquid held in a position effective in a direction substantially normal to the structures'' longitudinal axes, said longitudinal structures each comprising between its ends an elongated portion whose length changes directly with changes in ambient temperature, and elongated compensator means disposed substantially in longitudinal alignment with said portion whosE length changes inversely with changes in ambient temperature in a manner whereby the overall length of the structure remains substantially constant.

6. A length-change compensator for use in combination with an elongated member whose length changes directly with changes in ambient temperatures to produce a structure having an overall length which is substantially independent of temperatures comprising a pair of elongated relatively reciprocable interconnected parts having spaced-apart relatively movable outer ends which are interposed, biasing means operatively interposed between and acting on said parts urging the same under all circumstances to move relative to one another in a direction tending to increase the distance between said outer ends, and means containing a captive body of positive-temperature-coefficient liquid, with such liquid held in a position effective to act on said parts in a manner producing relative movement therebetween which increases the distance between said outer ends under all circumstances with a temperature decrease, and which decreases such distance under all circumstances with a temperature increase.