US 3904129 A
Description (OCR text may contain errors)
Elited States Patent [191 Lorene [4 1 Sept. 9, 1975 HYDRAULIC SYSTEM FOR VEHICULAR SPREADER  Inventor: Allan L. Lorenc, Fairfax, Iowa  Assignee: Highway Equipment Company,
Cedar Rapids, Iowa  Filed: Sept. 16, 1974  Appl. No.: 506,558
 [1.8. Cl. 239/650; 137/48; 214/58  Int. Cl. AOlC 3/06; A01C 7/08  Field of Search 239/660, 157, 650, 670; 214/58; 137/48  References Cited UNITED STATES PATENTS 3,441,039 4/1969 Rawson 239/650 Primary ExdminerLloyd L. King Attorney, Agent, or Firm-Dawson, Tilton, Fallon &
Lungmus  ABSTRACT A vehicular spreader has a pressure-compensated flow control valve receiving fluid from a variable displacement pump. Bypass fluid from the valve controls the displacement of the pump. The controlled flow of the valve feeds a manual selector valve having two positions. In one position, the selector valve feeds constant speed spinner motors for dispensing salt or the like. Connected in series with the spinner motors is a rateresponsive differential control valve which controls the speed of the conveyor motor feeding materials to the spinner as a function of ground speed of the vehicle. A feedback signal from the conveyor motor to the differential control valve insures an accurate, quick response even at low speeds. In another position, the selector valve permits high-speed operation of the conveyor for pit dumping with the differential control valve closed, or the use of an auxiliary hydraulic device with the differential control valve opened.
7 Claims, 4 Drawing Figures HYDRAULIC SYSTEM FOR VEI-HCULAR SPREADER BACKGROUND AND SUMMARY The present invention relates to hydraulic control systems; and more particularly, it relates to a hydraulic control system for a spreader of the type used to dispense material from a moving vehicle. In a system of this type it is desirable that the amount of material spread over a given area by the vehicle be controlled to give a constant coverage per area, even though the vehicle speed may vary.
One such system is disclosed in the co-owned Raw son US. Pat. No. 3,441,039, issued Apr. 29, 1969.
In such systems, for example, in a salt spreader used on highways or a lime and fertilizer spreader used in agriculture, a large hopper is mounted on a truck, and a conveyor is located beneath the discharge aperture of the hopper for feeding materials to one or more spinners at the rear of the vehicle. The ground speed of the vehicle is sensed, and a signal (either electrical, mechanical or hydraulic) representative of the ground speed is generated and used to actuate a control valve associated with a variable speed motor driving the conveyor. As the vehicle'speeds up, the speed of the conveyor motor is increased, and vice versa.
In these systems, it has been the practice to use a control valve which employs a spring-actuated spool valve to shunt hydraulic fluid from the conveyor motor. In the above-identified patent, a separate mechanical system is employed for controlling the flow as a function of vehicle ground speed.
These and other prior systems have encountered control problems at low vehicle speeds which require con trol of the hydraulic conveyor motor at relatively low speeds. The friction and inertia in the spring-biased valve do not permit a smooth, linear motor speed control, such problems being referred to as striction. Still another problem that is present at higher speed ranges is huntingthat is, due to the nature of the control, the system seeks a speed for the conveyor motor and then overshoots it and must reduce. In other words, the control of the conveyor motor again is not smooth, and desirably, it could be more accurate.
In the present invention, a variable displacement pump is driven by the vehicles engine. The pump feeds a pressure-compensated flow control valve. The bypass fluid from the valve controls the displacement of the pump, and the controlled flow of the valve feeds a manual selector valve having two positions. In one position, the selector valve feeds one or more constant speed spinner motors for dispensing material.
Connected in series with the spinner motors is a rate-responsive pressure differential control valve which controls the speed of a conveyor motor feeding materials to the spinners. The differential control valve receives one input from a remote speed sensing device generating a mechanical signal representative of vehicle speed, and a second mechanical feedback signal representative of the present speed of the conveyor motor. These two signals, and more particularly the difference between them, controls the positioning of an orifice spool for shunting fluid from the conveyor motor, and thereby decreasing its speed, as the vehicle slows down. Conversely, the position of the orifice spool is controlled to feed more fluid to the conveyor motor as the vehicle speed increases.
As the speed of the vehicle engine increases, the speed of the pump increases, thereby increasing its output volume. This volume, in turn, increases the pressure of the bypass fluid from the flow control valve to de-stroke the pump. Thus, a substantially constant flow is provided from the controlled flow output of the valve with a minimum of power used to regulate the flow.
The feedback control of the differential control valve has been found to insure an accurate response even at low speeds, and the response is quick at all speeds. Further, since the valve has a mechanically controlled variable orifice, control of the conveyor motor is continuous. Still further, the problem of hunting described above has been eliminated as have the problems associated with most spring-biased control valves.
When the manual selection valve is in a second position, the spinner motors are not connected in the hydraulic circuit, and this permits high-speed actuation of the conveyor motor for pit dumping, in which case the differential control valve is capable of being closed manually to render conveyor motor speed independent of vehicle speed. Further, with the manual selection valve in the second position, the system permits use of an auxiliary device, if desired, by opening the differential control valve and using quick disconnects to insert the auxiliary device into the circuit.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.
THE DRAWING FIG. 1 is a schematic diagram of a hydraulic system incorporating the present invention;
FIG. 2 is a schematic diagram similar to FIG. 1, wherein the solid lines indicate fluid flow in using the present system with an auxiliary hydraulic speed control device;
FIG. 3 is a view similar to FIG. 1 wherein the solid lines indicate a fluid flow when using the system for spinner speed control to dispense material as a function of vehicle ground speed; and
FIG. 4 is a view similar to FIG. 1 wherein the solid lines indicate fluid flow for conveyor pit dumping speed control.
DETAILED DESCRIPTION Referring then to FIG. 1, reference numeral 10 generally designates a fluid reservoir, and it is shown in two locationsat the upper left-hand corner and at the lower right-hand corner of FIG. 1 and the other drawings as well. As indicated, each of the drawings shows the same elements and possible interrelationships between the elements; however, the system may be set up for different modes of operations, and in FIGS. 2-4, the solid lines of conduit represent actual fluid flow as the system is set up to perform the various functions illustrated in those respective drawings.
Reference numeral 11 indicates a variable displacement hydraulic pump having an inlet port 12 receiving fluid from the reservoir 10 and discharging it through an outlet 13.
The pump 11 may be a radial piston, variable displacement hydraulic pump manufactured and sold under the designation PR-24, PR-30, PR-40 or PR- Jy John Deere & Company of Moline, Ill. The pump is iriven by a shaft which, in turn, is driven by the Jrime mover of the vehicle on which the system is in- ;talled, although obviously a secondary prime mover :ould be used. Variation of the pump displacement is iccomplished by hydraulic rather than mechanical neans; and for this purpose, a flow control inlet port 17 s provided. As the flow through the flow control inlet )ort 17 increases, the pressure increases to reduce the iisplacement of the pump or destrokes the pump.
The output of the pump 11 is fed through a conduit l8 to the inlet of a manually adjustable pressure- :ompensated flow control valve generally designated 20 which includes an outlet port 21 for controlled flow jthat is, a constant flow of fluid depending upon the ietting), a bypass flow port 22, and an inlet port 23. Fluid from the bypass port 22 is fed back to the flow :ontrol input port 17 of the pump 11 by means of a :onduit 24, shown in dashed line. The output of the lalve 20 may be controlled manually, and this is diagrammatically represented by the arrow 27. One such lalve, although the invention is not so limited, is part Io. FC-Sl, sold by Brand Hydraulic, Inc., of Omaha, \leb. The output of the valve 20 is coupled through a :onduit 28, and the fluid flow through the conduit 28 s substantially constant depending upon the setting of :he valve 20, as manually controlled, preferably by a ever located in the cab of the vehicle on which the syszem is mounted. I
The combination of the pump 1 l and valve 20, as dis- :losed, is considered an important feature of the invenzion. They cooperate to achieve a controlled flow 1hrough the conduit 28 which is substantially constant et manually variable, and which is quite efficient in :erms of power consumed by the hydraulic system, particularly in view of the fact that the pump 11 is driven )y a variable speed source, namely, the prime mover of :he vehicle. It must be appreciated that the dispensing ate of the material is controlled by the ground speed )f the vehicle, not the engine speed. For example, asiuming a constant output flow from the flow control /alve 20, if the vehicle engine speeds up, the output "low of the pump ll 1 will increase, and the flow through he feedback conduit 24 will also increase slightly. This low may normally be a nominal 2 gallons per minute, vhereas the flow through the conduit 28 may be of the rder of 25-35 gallons per minute. The increased flow n the feedback conduit 24 will de-stroke the pump 11, hereby maintaining a substantially constant volume. If he engine speed slows down, the resulting flow in the 'eedback conduit 24 will be reduced, and the displacenent of the pump 11 will be increased. Hence, this porion of the system produces a substantially constant low in the conduit 18 with a minimum of power loss. n some prior systems, an increase in pump speed vould merely increase the amount of fluid that was Jumped directly back to the reservoir through a bypass 'alve associated with the spinner motors. Hence, this :xcess fluid represented a substantial amount of unused :nergy since the fluid was being returned to the reser- 'oir through a pressure differential which was the out- )ut pressure of the main pump.
The conduit 28 is connected to a manual selector 'alve 30 having two positions, designated respectively i1 and 32. V
The output 31a of the first position of the selector 'alve 30 is connected by means of a conduit 33 to the input of a pressure-compensated flow divider generally designated by reference numeral 35 and having a first output port 36 and a second output port 37. The output ports 36, 37 are connected respectively to a pair of spinner motors 38, 39, the outputs of which are connected in common to a conduit 40 which feeds the input of a rate-responsive differential control valve 42. The output of the valve 42 is connected by means of a return conduit 43 to the reservoir 10.
The output port 32a of the second position of the manual selector valve is connected to the conduit 45 which is provided with a quick disconnect coupling 46 including a first half 46a shown connected to a mating second half 46b whereby the output 32a is connected to the input of the differential control valve 42.
A second quick disconnect coupling including halves 49, 50, shown in the connected positions in FIG. 2 are used to connect the output 32a of the manual selector valve 30 to an auxiliary hydraulic device (not shown) by means of a feed conduit 51 and a return conduit 52, as will be disclosed. The differential control valve 42 includes a pressure relief 55 and a spool indicated by the arrow 56. The position of the spool 56 controls the size of the orifice, and hence, the flow to outlet port 63. Such a valve is disclosed in US. Pat. No. 3,703,810, which is incorporated herein by reference. Briefly, the position of the spool 56 is controlled by a first input signal from a remote speed sensing device sensing ground speed of the vehicle. This is a mechanical signal wherein a first input shaft represented by the dashed line 60 is rotated at an angular velocity representative of the ground speed of the vehicle. A second input control shaft represented by the dashed line 61 is rotated at an angular velocity representative of the speed of a conveyor motor 62. Thus, the rotation of the shaft till is a feedback signal representative of the speed of the hydraulic motor driving the conveyor beneath the hopper of the vehicle. The inlet port 57 of the valve 42 is connected to the inlet of the conveyor motor 62, and the outlet port 58 of the valve 42 is connected to the outlet of the conveyor motor 62. Thus, the differential control valve 42 is connected hydraulically in parallel with the conveyor motor 62. As the ground speed of the vehicle increases, the shaft 60 rotates at a higher angular velocity, thereby rotating the spool 56 slightly to decrease the orifice of the valve 42 and force more hydraulic fluid to the conveyor motor 62, causing it to increase in speed. The increase in speed of the conveyor motor 62, in turn, causes an increase in the rotational velocity of the shaft 61 which, in turn, moves the spool 56 via the feedback connection until equilibrium is established.
The differential control valve 42 has been found to be very effective and useful in the system of the present invention because it does not exhibit the primary problems associated with spring-loaded or biased hydraulic control valves in that it operates accurately and reliably at low speeds, does not exhibit the phenomenon of hunting for an equilibrium position because there is no overshoot in seeking equilibrium and has a very rapid response time and is therefore able to follow changes in ground speed very well.
Turning now to FIG. 3, the system is shown set up in the spinner speed control modethat is, this is the normal mode of dispensing materials at the rear of the vehicle as a function of ground speed. In this mode, the
manual selector valve 30 is set in the first position 311,
and the manual pressure compensated flow control valve is also set by the operator. This valve gives the operator an opportunity to vary the speed of the spinner motors 38, 39, depending upon the type of material being dispensed and the coverage desired. For example, the setting for dispensing fertilizer on a field may be different than that used to spread salt on a highway. In either case, it will be observed that the speed of the vehicle should control the speed of the conveyor motor so as to accomodate changes in vehicular speed while achieving the same spreading rate.
In this mode, the pump 11 pumps fluid through the pressure compensated flow control valve 20, and through the manual selector valve to the conduit 33 which feeds the pressure-compensated flow divider 35. The flow divider 35 feeds equal amount of fluid to the spinner motors 38, 39; and the fluid re-combines and is fed via conduit 40 to the differential control valve 42 and conveyor motor 62, as discussed. From these, the fluid is returned to the reservoir 10 by means of conduit 43. It will be appreciated that in this mode, the feedback conduit 24 connecting the bypass flow port 22 of the valve 20 is also connected in circuit with the flow control input port 17 of the pump 11. Thus, flow in the conduits 18 and 28 is substantially constant, once set, and independent of the variations in engine speed within the range of the pump. The spinner motors 38, 39 are constant speed motors. The differential flow control valve 42 is regulated in accordance with the ground speed of the vehicle and the feedback signal representative of the speed of the conveyor motor 62, as represented by the shaft 61. Thus, in this mode, the material is dispensed at a predetermined, controlled rate as a function of vehicle ground speed.
Turning now to FIG. 4, the manual selector valve 30 is set in the second position 32 wherein the conduit 28 communicates with the outlet port 32a and the conduit 45. In this mode, the disconnect half 46a is connected to disconnect half 46b to feed the differential control valve 42 directly. However, the differential control valve 42 is closed manually so that all of the fluid passing through conduit 45 is fed directly to the conveyor motor 62, thereby operating it at top speed.
In this mode, of course, the hydraulic pump 11 and pressure-compensated flow control valve 20 are connected in circuit as previously disclosed. This mode is used, for example, when it is desired to dump the contents of the truck hopper. The truck, of course, will be at a stop, so it is not desired that the dumping be accomplished as a function of ground speed, which remains zero. Thus, the differential control valve 42 is closed, and the speed of the conveyor motor 62 is controlled by the pressure-compensated flow control valve 20.
Turning now to the mode of operation depicted in FIG. 2, the system is shown set up for use with an auxiliary hydraulic device, such as a hydraulic-motor-driven charging elevator, if desired, or similar apparatus. In this case, the manual selector valve 30 is again in the second position 32, and the pump 11 and pressure compensated flow control valve 20 are connected in circuit as discussed above. The disconnect half 46a is connected to the disconnect half 49, and disconnect half 50 is connected to disconnect half 46b, thereby communicating the auxiliary feed conduit 51 and auxil iary return conduit 52 with the device, and connecting it in circuit with the differential control valve 42 which is automatically opened when the vehicle is stopped or input is deactivated to short-circuit the conveyor motor 62. Thus, all of the fluid flowing through conduit 28 from the pressure-compensated flow control valve 20 flows through the selector 30, circuit 51, the auxiliary device, circuit 52, valve 42, and into the reservoir 10. It is understood that the speed of the auxiliary device is controlled by the pressure compensated flow control valve, 20, which in turn controls the pump delivery for controlled flow of zero G.P.M. to maximum pump delivery.
From the above description, another advantage of the invention will readily be appreciated. With the control lever 27 in the vehicle cab, an operator is able to shut off the spinner motors and conveyor motors simply by reducing the controlled output flow of the valve 20 to zero. Thus, all of the bypass fluid is fed back to de-stroke the pump 11. This reduces the load on the prime mover, thereby saving power. If electric or hydraulic clutches are not used and when the pumps are driven continuously, unnecessary power losses occur.
Having thus described in detail a preferred embodiment of the present invention, persons skilled in the art will be able to modify certain portions of the hydraulic circuit illustrated, and to substitute equivalent elements for those which have been disclosed while continuing to practice the principle of the invention; and it is, therefore intended, that all such modifications and substitutions be covered as they are embraced within the spirit and scope of the appended claims.
1. A hydraulic system for use with a vehicular spreader having a source of material to be spread, a conveyor beneath said material for conveying the same to a spinner driven by spinner motor means, said conveyor being driven by a conveyor motor, said vehicle further including a prime mover, the improvement comprising: a variable displacement pump driven by said prime mover and including a flow control input port; pressure-compensated flow control valve means receiving fluid from said pump means for delivering the same at a generally constant flow rate to an output port and including a bypass port; means for connecting the bypass port of said flow control valve to the flow control inlet port of said pump; means connecting said spinner motor means in circuit with said pump; differential flow control valve means connected across said conveyor motor and in circuit with said spinner motor means and responsive to a first control signal representative of the ground speed of the vehicle and a second feedback signal representative of the speed of said conveyor motor to adjust the flow of fluid to said conveyor motor.
2. The apparatus of claim- 1 wherein said fluid control valve means is rate-responsive and includes an aperture, the size of which is controlled by a movable spool, the position of said spool being responsive both to said ground speed control signal and said feedback signal representative of the speed of said conveyor motor.
3. The apparatus of claim 1 wherein said flow control valve means is manually adjustable, whereby the output thereof can be adjusted according to the requirements of the material being spread.
4. The apparatus of claim 3 wherein said flow control valve includes a control lever in the operators cab, whereby when the controlled output thereof is shut off,
he bypass output de-strokes the pump to shut down he spreader system during over-the-road travel.
5. The apparatus of claim 1 further comprising a seector valve having a first and a second position and :onnected to the controlled flow output of said flow :ontrol valve, the first output thereof communicating with said spinner motor means; a disconnect communi- :ating said manual selector valve in said second posi- IiOl'l directly with said differential flow control valve and said conveyor motor, whereby when said selector lalve is in said second position and said differential lalve is closed, said conveyor motor may be operated at desired speed as controlled by said pressure compen- ;ated flow control valve in a pit dump mode.
6. The apparatus of claim 5 further comprising sec- )nd quick disconnect means adapted to replace said first quick disconnect means to interrupt the fluid cir- :uit for the insertion of an auxiliary hydraulic device, whereby when said differential valve means is open, ;aid auxiliary device may be operated by said pump and ;aid conveyor motor is bypassed.
7. In a hydraulic system adapted for use with a vehicular spreader wherein the vehicle is equipped with a prime mover, spinner motor means operating a spinner, and a conveyor motor operating a conveyor to move material from a storage location to said spreader, the improvement comprising: a variable displacement pump having an input flow control port associated with a mechanism for de-stroking said pump as the volume at said inlet flow control port increases; pressurecompensated flow control valve means delivering fluid from said pump at a constant flow rate and including a bypass port; means for communicating said bypass port with said input flow control port of said pump means; means communicating said spinner motor means with the output of said flow control valve; and a differential flow control valve having a spooloperated orifice connected across said conveyor motor, the position of said spool being responsive to a first signal representative of ground speed of the vehicle and a second signal representative of the speed of said conveyor motor.