US3877345A

US3877345A - Displacement sensitive automatic diverter valve

Info

Publication number: US3877345A
Application number: US416955A
Authority: US
Inventors: Edward J Ohms; Lawrence F Schexnayder
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1973-11-19
Filing date: 1973-11-19
Publication date: 1975-04-15
Anticipated expiration: 1992-04-15
Also published as: JPS5083680A; GB1484506A

Abstract

Hydraulic drive circuitry for an elevator equipped scraper vehicle. Separate circuitry including pump means and motor means for operating the elevator drive and for steering the vehicle respectively. A portion of steering pump means flow is selectively directed to the elevator drive circuitry and such directed flow is automatically returned to the steering circuitry to provide maximum flow when needed. Diverter valve means are mechanically linked to the steering control mechanism so that the valve automatically responds to the movement of such control mechanism for directing steering flow from the elevator drive circuitry to the steering circuitry upon demand. Upon fulfillment of steering demand, flow is again automatically supplied to the elevator drive circuitry from the steering circuit by means of the mechanically linked diverter valve.

Description

United States Patent Ohms et al.

[451 Apr. 15, 1975 [75] Inventors: Edward J. Ohms, Washington;

Lawrence F. Schexnayder, Joliet, both of I11.

[73] Assignee: Caterpillar Tractor Company,

Peoria, Ill.

[22] Filed: Nov. 19, 1973 [21] Appl. No.: 416,955

[52] U.S. Cl. 91/412; 60/421; 60/422;

[51] Int. Cl. F15b 11/16 [58] Field of Search 60/421, 422; 91/412, 414

[56] References Cited UNITED STATES PATENTS 2,363,179 ll/l944 Harrington et al. 91/412 2,414,451 l/1947 Christensen 3,386,344 6/1968 Junck et al. 91/414 PILOT SUPPLY DISPLACEMENT SENSITIVE AUTOMATIC DIVERTER VALVE Primary Examiner-Edgar W. Geoghegan Assistant Examiner-Wm. F. Woods Attorney, Agent, or FirmPhillips, Moore, Weissenberger, Lempio & Strabala [57] ABSTRACT Hydraulic drive circuitry for an elevator equipped scraper vehicle. Separate circuitry including pump means and motor means for operating the elevator drive and for steering the vehicle respectively. A portion of steering pump means flow is selectively directed to the elevator drive circuitry and such directed flow is automatically returned to the steering circuitry to provide maximum flow when needed. Diverter valve means are mechanically linked to the steering control mechanism so that the valve automatically responds to the movement of such control mechanism for directing steering flow from the elevator drive circuitry to the steering circuitry upon demand. Upon fulfillment of steering demand, flow is again automatically supplied to the elevator drive circuitry from the steering circuit by means of the mechanically linked diverter valve.

10 Claims, 1 Drawing Figure TO STEERING PATENTEUAPR I 51975 3,877, 345

PILOT SUPPLY STEERING 1 LINDERS DISPLACEMENT SENSITIVE AUTOMATIC DIVERTER VALVE BACKGROUND OF THE INVENTION Self-loading scrapers utilizing elevator mechanisms to assist in scraper bowl loading have become reliable high production earthmoving tools. High production work usually requires the capability for a number of different elevator operation speeds for the most efiicient loading of various different materials. The provision of a selection of elevator drive speeds carries the further advantage that elevator flight velocity may be readily matched to suit the velocities of the vehicle and, of the material which flows over the scraper cutting edge.

For such reasons, variable speed elevator drive mechanisms of various constructions have been provided. However, many of such mechanisms require special electrical drive arrangements or require prohibitively expensive variable displacement hydraulic pumps or are adaptable only to vehicles having electrical traction systems.

Some prior art elevator drive mechanisms provide a combination of the hydraulic fluid flow which is intended to supply the bowl and ejector controls with that intended for the elevator drive motor means to provide higher elevator drive speeds. In such mechanisms, use of the elevator drive pump means alone provides normal speed operation. Such arrangements, however, are often unsatisfactory since priority must be given to the bowl and ejector control circuits at the expense of the speed controls for the elevator. An example of such a system is shown in U.S. Pat. No. 3,258,926 to Junck et al, of common assignment herewith.

Another prior art system utilizes a portion of the hydraulic fluid used for steering the scraper vehicle for the elevator drive motor means for higher speed ranges thereof. With such systems, since at least a portion of the usual steering flow is available for steering at all times, the scraper vehicle will maintain some directional control even while the elevator mechanism is operating at high speeds. The diversion of a portion of the steering fluid to operate the elevator mechanism is a particularly advantageous arrangement during loading of the bowl since at such time the vehicle is normally travelling in a straight line. Even when direction of the vehicle is changed during loading, slow steering speeds are normally quite suitable and usually require only a portion of the total available steering flow for steerage.

While steering flow diversion systems have been generally the most desirable approach, prior art arrangements of this type have not been totally satisfactory. For example, various versions of such a system are shown. in U.S. Pat. No. 3,386,344 to Junck et al, of common assignment herewith. In one of the patented embodiments, flow diversion from the steering circuitry to the elevator circuitry is accomplished by means of a pressure sensitive diverter valve. Because this valve depends for actuation upon system pressure, which is constantly variable, shifting of the diverter valve is erratic and may or may not cause the supplyof necessary fluid to the steering circuit to accommodate a necessarily sharp steering maneuver when the elevator is being driven in a high speed range. The pressure sensitive diverter valve must respond to the pressure which actually depends upon a balance between two independent pressure sources; that is, the pressure extant in the elevator drive circuitry and in the steering circuitry.

An alternate embodiment of the pressure responsive system provides a separately manually controlled mechanical diverter valve. With this system, the operator is required to press a pedal connected by mechanical linkage to the diverter valve for appropriate actuation. This system obviously requires operator distraction from the normal work cycle and is a particularly inefficient system.

SUMMARY AND OBJECTS OF THE INVENTION The instant invention provides a positive-acting efficiently operable multiple speed elevator drive mechanism for a scraper vehicle wherein some vehicle steering pump flow is selectively diverted to an elevator drive motor to provide a higher speed elevator operation. A diverter valve positively controlled by pressurized fluid from a pilot valve which is mechanically actuated by the steering control mechanism automatically diverts steering flow during normal steering conditions and automatically discontinues such diversion upon the accomplishment of a drastic steering maneuver.

The main object of the present invention is to provide a displacement sensitive automatically-operating diverter valve directly responsive to movements of a steering valve which enables the automatic diversion of hydraulic flow from the steering circuit of an elevator scraper to. the elevator circuit thereof for high speed elevator operations while assuring the automatic provision of adequate steering flow to the steering circuit whenever high steering rates are required and assuring the return of such flow to the elevator circuit upon cessation of such steering demands.

Other objects and advantages of the invention will become apparent from the following description and drawing.

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE is a schematic representation of the fluid circuitryfor both the elevator and steering components of a scraper vehicle embodying the principles of the present invention.

DETAILED DESCRIPTION With reference to the drawing, the circuitry and components of the present invention may be appreciated. At 10 is shown a portion of the elevator speed control valve for the elevator of the scraper vehicle. The valve has a spool 12 which, when reciprocated, varies the amount of fluid transmitted to the elevator drive motor 14 with consequent speed control thereof. The position of the spool 12 is determined by that of the multi- .positionable control lever 16. It will be noted that,

through crank member 1 5, the lever 16 also directly controls the position of a spool 18 in a pilot control valve 20, the purpose of which will be explained more fully hereinafter.

The elevator circuitry also includes

hydraulic fluid pumps

22 and 24 which supply fluid to the elevator speed control valve 10 for communication to the drive motor 14 in the usual manner. The pumps draw fluid from a supply sump 25 and return excess fluid thereto. It will be noted that the control lever 16 may be moved selectively to four different positions indicated at l, N,

2, and 3 in the drawing. The lever is moderately restrained in each of these positions by detent means 13 until a'relocation is desired. The circuitry is arranged such that with the control lever 16 disposed in position 1, hydraulic fluid from the pump 24 alone will be communicated to the elevator drive motor 14. Control valve is constructed so that when the lever 16 is in position 1, hydraulic fluid from the pump 22 will be bypassed back to the sump through a drain line 26.

When the control lever 16 is moved to the neutral or N position shown in the drawing, the valve 10 causes by-passing of the full flow from both

pumps

22 and 24 back to the sump 25 through the line 26.

Movement of the control lever 16 to the second position marked 2 in the drawing causes the flow from both

pumps

22 and 24 to be communicated to the elevator drive motor 14 to drive the elevator at a speed faster than that possible with the lever in the 1 position. Finally, the highest elevator speed attainable in the system results from movement of the lever 16 to the position 3 shown in the drawing.

With the lever 16 in the third position, not only is the full delivery from both

pumps

22 and 24 communicated to the elevator drive motor 14 but also a portion of the hydraulic fluid flow from the steering circuitry is diverted to supplement the flow to the elevator drive motor. As will become apparent hereinafter, however, the steering function has a higher priority than the elevator speed function and, upon a requirement for high steering fluid flow, such as during a sharp turning maneuver, the diversion of steering circuit flow to the elevator drive motor is prohibited. lt should be noted that the detent means 13 enables the operator to manipulate other vehicle controls while the elevator is being driven.

The control lever 16, when shifted to the high speed position 3, need not be repositioned when the operator is forced to make a sharp or high speed turn. When such a maneuver is to be made which would require full steering flow, the present system positively reacts to the displacement of a steering valve and automatically causes total available steering pump flow to be directed to the steering components without regard to the needs of the elevator drive. After the operator has completed the high flow steering maneuver and has returned the steering valve 30 to a moderate range, steering valve movement will be positively transmitted to a valve means 28 which will automatically condition a pilot system to direct a portion of the previously diverted steering circuit flow back to the elevator drive motor means.

In more detail, when the control lever 16 is shifted to either the first or second operating positions, a line 32 which communicates with a source of pilot fluid pressure will be held out of communication with another line 34 by virtue of the position of a spool 18 in a valve 20. As will be appreciated by reference to the drawing, at such time a land of the spool 18 blocks the outlet port to the line 34 in the valve 20.

However, when the control lever 16 is moved to the third position, a land of the spool 18 will be moved leftwardly away from the outlet port and the lines 32 and 34 will be in communication through an area surrounding an annular groove 36 in the spool 18. With the lines I 32 and 34 in communication, pilot pressures will be directed from the source (not shown) to the valve 28 into,

an area formed around an annular groove 29 of a spool 40 which is reciprocally received within a bore of the valve 28. With spool 46 positioned as shown in the drawing, pilot pressure from the line 34 will be communicated to a line 42.

Fluid pressure in the line 42 is transmitted to a portion of a diverter valve, shown generally at 46. Such fluid acts upon the end portion of a spool 44 to urge movement of the spool rightwardly against the force of a spring 48. Upon such movement of the spool, there will be fluid communication between a line 50 and a line 52 via an annular groove 54 in the spool 44. When such communication exists, steering circuit flow from one of two steering pumps 56, 59 will be directed from the line 50 through the line 52 to the elevator drive motor 14. In such mode of operation, the steering pump means 56 supplements flow from the elevator pump means 22 and 24 to drive the elevator motor at its highest possible speed.

Steering the vehicle is accomplished by means of an operator controlled linkage 58 which directly actuates a steering valve system which selectively directs fluid under pressure to suitable hydraulic motors through lines 57 and 61. The motors act between a portion of the vehicle frame structure and the wheels thereof for steerage in a conventional manner.

When the elevator is being driven at its highest rate and the selector lever 16 is in position 3, the operator may make slight steering corrections by manipulating the control linkage 58 without changing the speed of the elevator, even though movements of the steering valve 30 and linkage 58 are transmitted directly to the spool 40 of the valve 28 by means of connecting linkage 41. This is so because the disposition of the spaced lands 31 and 33 of the spool 40 are such that slight movements of the spool will not cause communication between the

lines

34 and 42 to be blocked so as to discontinue pressure application to the diverter valve 46.

When normal or minor steering corrections are made, the steering pump 59 is adequate to supply the steering motors with actuating pressure. However, if a sharp turn is to be made which would require a high rate of steering flow, the operator would drastically reposition the control linkage 58 to substantially shift the steering valve 30 to one of its maximum positions. Such movement of the linkage 58 and steering valve 30 would directly transmit a like movement through the linkage 41 to the spool 40 of the valve 28. The land 33 would block passage between the

lines

34 and 42 and discontinue pilot pressure communication to the valve 46. Upon termination of such communication, pressure from the line 42 would be transmitted to drain through the line 60. With line 42 communicating with drain, spool 44 would shift to the left under the influence of the spring 48 and interrupt the flow from the pump 56 to the elevator driver motor 14 and divert such flow from line 50 to the line 62 for direct transmittal to the steering valve 30 and respective steering motor supply lines 57 and 61.

During this entire operation the lever 10 would be held in position 3 by detent means 13 and would require no operator adjustment. Once the drastic steering maneuver had been completed and the operator returned the control linkage 58 to a central range, straight-line position, the spool 40 of the valve 28 would return to a position which would allow communication between the

lines

34 and 42 to condition the valve spool 44 to return rightwardly to provide recommunication of the steering pump means 56 and the elevator drive motor 14 via the

lines

50 and 52.

While the invention has been described with particular reference to the preferred embodiments, it is apparent that variations and modifications are possible within the purview of the inventive concepts. No limitation with respect to such variations and modifications is intended, except by the scope of the appended claims.

We claim:

1. A fluid control system for controlling flow of pressure fluid from first and second pump means to first and second fluid motor means for driving said motor means including; first fluid communication means for communicating fluid from said first pump means to said first fluid motor means, second fluid communication means for communicating fluid from said second pump means to said second fluid motor means, said first fluid communication means including first control valve means for controlling fluid flow to said first motor means and for controlling the speed of operation of said first motor means, second control valve means for controlling the amount of fluid flow to said second motor means, diverter means for selectively diverting some fluid flow from said second fluid communication means to said first fluid communication means, said diverter means including sensing valve means and mechanical linkage means between said sensing valve means and said second control valve means for directly mechanically transmitting movements of said second control valve means to said sensing valve means for automatically conditioning said diverter means to redirect diverted fluid from said first fluid communication means to said second fluid communication means in response to movement and positioning of said second control valve means.

2. The invention of claim 1, wherein said diverter means further include pilot valve means for transmitting pilot fluid pressure to said sensing valve means in equipped with an elevator device, wherein said first fluid motor means include a variable speed fluid motor for said elevator device in said scraper vehicle and wherein said second fluid motor means include a plurality of fluid motors for steering said scraper vehicle.

6. The invention of claim 4, wherein said leverlinkage means is selectively manually positionable in any of a neutral position or first, second or third sequentially placed speed positions and wherein said diverter means is operative to divert fluid flow from said second fluid communication means to said first fluid communication means only when said lever-linkage means is disposed in said third position, and detent means associated with said first control valve means for retaining said lever-linkage means in each of said neutral or first, second, and third positions.

7. The invention of claim 3, wherein said sensing valve means include a sensing spool member which is directly connected for movement with said mechanical linkage means and which responds directly to movements of said second control valve means, said spool member being axially moveable within said sensing valve means between opposed extreme end positions and a mid-range between said extreme positions, said sensing spool member acting to block flow of pilot pressure from said pilot valve means to said diverter valve means when disposed in either of said opposed extreme end positions and acting to permit flow of pilot pressure from said pilot valve means to said diverter valve means when disposed in said mid-range.

8. The invention of claim 5, wherein said mechanical linkage means include a manually activated operator control lever for causing selective movement of said second control valve means and said sensing valve means to control the flow of fluid transmitted to said second motor means for steering said scraper vehicle.

9. The invention of claim 8, wherein said second pump means include primary and secondary fluid pumps and wherein said primary fluid pump communicates at all times with said second motor means for steering said vehicle.

10. The invention of claim 3, wherein said diverter valve means include a diverter spool member mounted for reciprocating movement within said diverter valve means, said diverter spool member being moveable in a first direction under the influence of pilot pressure from said sensing valve means and said diverter spool member being biased for movement in the opposite direction by mechanical spring means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 77,3 5

INVENTORtS) Edward J Ohms, et al it is certified that error appears in the above-identified patent and that said Letters Patent are hereb corrected as shown below On the Title Page, Item [73], change the spelling of the assignee's corporate name from "Caterpillar Tractor Company" i to Caterpillar Tractor Co.

Signed and Scaled this twenty-second D3) of July 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Attrslirig Officer Commissioner of Parents and Trademarks

Claims

2. The invention of claim 1, wherein said diverter means further include pilot valve means for transmitting pilot fluid pressure to said sensing valve means in response to movement of said first control valve means.

3. The invention of claim 2, wherein said diverter means further includes diverter valve means for selectively directly connecting said first fluid communication means with said second fluid communication means in response to a pilot pressure signal from said pilot valve means and said sensing valve means.

4. The invention of claim 2, wherein said first control valve means and said pilot valve means are mechanically connected for simultaneous movement by lever-linkage means.

5. The invention of claim 1 in a scraper vehicle equipped with an elevator device, wherein said first fluid motor means include a variable speed fluid motor for said elevator device in said scraper vehicle and wherein said second fluid motor means include a plurality of fluid motors for steering said scraper vehicle.

6. The invention of claim 4, wherein said lever-linkage means is selectively manually positionable in any of a neutral position or first, second or third sequentially placed speed positions and wherein said diverter means is operative to divert fluid flow from said second fluid communication means to said first fluid communication means only when said lever-linkage means is disposed in said third position, and detent means associated with said first control valve means for retaining said lever-linkage means in each of said neutral or first, second, and third positions.