CA2390186C - Hydraulic system for a plowing and material spreading equipment - Google Patents
Hydraulic system for a plowing and material spreading equipment Download PDFInfo
- Publication number
- CA2390186C CA2390186C CA 2390186 CA2390186A CA2390186C CA 2390186 C CA2390186 C CA 2390186C CA 2390186 CA2390186 CA 2390186 CA 2390186 A CA2390186 A CA 2390186A CA 2390186 C CA2390186 C CA 2390186C
- Authority
- CA
- Canada
- Prior art keywords
- spreader
- valve
- valve means
- plow
- hydraulic system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01H—STREET CLEANING; CLEANING OF PERMANENT WAYS; CLEANING BEACHES; DISPERSING OR PREVENTING FOG IN GENERAL CLEANING STREET OR RAILWAY FURNITURE OR TUNNEL WALLS
- E01H5/00—Removing snow or ice from roads or like surfaces; Grading or roughening snow or ice
- E01H5/04—Apparatus propelled by animal or engine power; Apparatus propelled by hand with driven dislodging or conveying levelling elements, conveying pneumatically for the dislodged material
- E01H5/06—Apparatus propelled by animal or engine power; Apparatus propelled by hand with driven dislodging or conveying levelling elements, conveying pneumatically for the dislodged material dislodging essentially by non-driven elements, e.g. scraper blades, snow-plough blades, scoop blades
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/12—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for distributing granular or liquid materials
- E01C19/20—Apparatus for distributing, e.g. spreading, granular or pulverulent materials, e.g. sand, gravel, salt, dry binders
- E01C19/201—Apparatus for distributing, e.g. spreading, granular or pulverulent materials, e.g. sand, gravel, salt, dry binders with driven loosening, discharging or spreading parts, e.g. power-driven, drive derived from road-wheels
- E01C19/202—Apparatus for distributing, e.g. spreading, granular or pulverulent materials, e.g. sand, gravel, salt, dry binders with driven loosening, discharging or spreading parts, e.g. power-driven, drive derived from road-wheels solely rotating, e.g. discharging and spreading drums
- E01C19/203—Centrifugal spreaders with substantially vertical axis
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/162—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for giving priority to particular servomotors or users
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/022—Flow-dividers; Priority valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40523—Flow control characterised by the type of flow control means or valve with flow dividers
- F15B2211/4053—Flow control characterised by the type of flow control means or valve with flow dividers using valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
- F15B2211/41509—Flow control characterised by the connections of the flow control means in the circuit being connected to a pressure source and a directional control valve
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/42—Flow control characterised by the type of actuation
- F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/455—Control of flow in the feed line, i.e. meter-in control
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6052—Load sensing circuits having valve means between output member and the load sensing circuit using check valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6055—Load sensing circuits having valve means between output member and the load sensing circuit using pressure relief valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
- F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/78—Control of multiple output members
- F15B2211/781—Control of multiple output members one or more output members having priority
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Soil Working Implements (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
A hydraulic system for operating equipment for removing snow and/or ice from surfaces having a plow, and a spreader for spreading traction enhancing materials onto the surfaces comprises a fixed displacement pump, a priority valve for receiving all of the hydraulic fluid from the pump and directing it to a load sensitive spreader valve and a plow valve. The priority valve is mechanically biased to direct the hydraulic fluid primarily to the spreader valve. The pressure from the fluid directed to the spreader valve is used to oppose the mechanical bias while the load pressure from the spreader valve is used to augment the mechanical bias, such that the spreader valve receives the amount of hydraulic fluid required for its operation. The system further includes an orifice connected to a load sensing line in the spreader valve to bleed fluid from the line. The spreader may include a conveyor and/or an auger and a spinner for spreading materials, as well as a dispenser for liquid materials.
The metering devices for operating the components in the spreader may be solenoid or mechanically operated; the metering devices for operating the plow may be solenoid, air, hydraulic or mechanically operated.
The metering devices for operating the components in the spreader may be solenoid or mechanically operated; the metering devices for operating the plow may be solenoid, air, hydraulic or mechanically operated.
Description
HYDRAULIC SYSTEM FOR PLOWING AND MATERIAL SPREADING
EQUIPMENT
Field of the Invention The invention relates generally to equipment for removing snow and/or ice from roadways, and more particularly to a hydraulic system for controlling the equipment spreader and plow.
Background of the Invention The operation of equipment used for plowing or scraping snow and/or ice from roads, airport runways and similar surfaces and the spreading of traction enhancing material such as sand and/or salt requires the installation of a hydraulic system that supplies power to operate the spreader and plow equipment. The usual installation includes a single gear pump that pushes hydraulic fluid through an open center valve with a power beyond connection, which is used to operate the plow functions. The power beyond is connected to the pressure inlet of the spreader valve, from where it returns to a hydraulic fluid tank or reservoir, or is partially routed to the spreader's hydraulic motors. The principal problem of this circuit is the stoppage of 2o the spreader when any plow function is operated. Other solutions have been used to remedy this problem.
Tandem pumps may be used in two completely separate hydraulic circuits.
One pump supplies the plow hydraulic functions, the other one supplies the spreader only. Simultaneous operation is rendered possible for both the plow and the spreader, but several major inconveniences remain. The system is more expensive, more complicated, requires a larger hydraulic fluid reservoir and consumes more energy.
Another solution is the use of a variable displacement piston pump that is 3o usually controlled by sensing the load. The load sensing pump works in conjunction with closed center valves that share a common pressure supply, which is the pump.
This constitutes a normal load sensing circuit, with all its usual benefits.
The main problem associated with this solution is the very high cost of load sensing valves and pumps.
Canadian Patent 1,060,757 which issued on August 21, 1979 to Larson et al is an example of various types of hydraulic circuits based on a fixed displacement pump, a variable displacement pump or a load sensing pump. In this patent, the circuits are used in power steering systems, which selectively control the flow of fluid toa steering motor and an auxiliary device through the use of a priority valve.
1o Therefore, there is a need for a hydraulic system that provides hydraulic fluid to the spreader on a priority basis in spreader/plow equipment.
Summary of the Invention The invention is directed to a hydraulic system for operating equipment for Is removing snow and/or ice from surfaces having a plow, and a spreader for spreading traction enhancing materials onto the surfaces. The hydraulic system comprises a reservoir for hydraulic fluid, a fixed displacement pump for providing hydraulic fluid from the reservoir, a priority valve having an inlet port for receiving hydraulic fluid from the pump, a first outlet port and a second outlet port, whereby the priority valve 2o is mechanically biased to direct the hydraulic fluid from the inlet port primarily to the first outlet port. The system further includes a spreader valve having an inlet port coupled to the priority valve first outlet port and one or more metering device for controlling fluid flow through the spreader valve for operating the spreader, and a plow valve having an inlet port coupled to the priority valve second outlet port and a z5 metering device for controlling fluid flow through the plow valve for operating the plow. In addition, the system has means for transferring the pressure from the priority valve first outlet port to the priority valve to oppose the mechanical bias thereby directing fluid flow to the second outlet port, means for transfernng load pressure from the spreader valve to the priority valve through a load pressure line to augment 3o the mechanical bias, such that the amount of hydraulic fluid directed from the priority valve first outlet port is proportional to the load pressure from the spreader valve, and means for bleeding fluid to the reservoir from the load pressure transferring means.
In accordance with another aspect of the invention, an orifice is connected between the load pressure line and the reservoir to bleed fluid from the load pressure transferring means. The orifice may be located in the spreader valve.
With regard to a further aspect of the invention, the system may include a relief valve connected between the priority valve and the reservoir to relieve the pressure in the load sensing line. The relief valve may be located in the priority valve.
1o In accordance with another aspect of the invention, the metering device for controlling the fluid flow through the spreader valve may be solenoid operated or mechanically operated.
With respect to another aspect of the invention, the spreader may include a conveyor and/or auger and a spinner for spreading materials, as well as a liquid material dispenser.
Other aspects and advantages of the invention, as well as the structure and operation of various embodiments of the invention, will become apparent to those ordinarily skilled in the art upon review of the following description of the invention in conjunction with the accompanying drawings.
Brief Description of the Drawings The invention will be described with reference to the accompanying drawings, wherein:
Figure 1 illustrates the hydraulic system in accordance with the present invention;
Figure 2 is a schematic of a priority valve used with the present invention;
and Figure 3 is schematic of an alternate spreader valve.
Detailed Description of the Invention The hydraulic system in accordance with the present invention is illustrated in figure 1. A fixed displacement pump 1 pumps hydraulic fluid or oil at a constant flow and variable pressure from the reservoir 2 into the inlet port P3 of a priority valve 3 where the flow is divided between the priority outlet port CF and the excess flow port EF. The priority outlet port CF is coupled to the inlet port P4 of a load sensing spreader valve 4 by line 6 while the excess flow port is coupled to the inlet port P5 of an open-centred plow valve S by line 7. For purposes of illustration, the plow valve S
is shown as a conventional three-position, four way valve. By way of example, the load sensing spreader valve 4 is shown as having a first and a second branch with metering devices 41 and 42. Metering device controls fluid flow to motor for a 1 o material transporting device such as a conveyor, an auger or a combination of both, through outlet port P41, while metering device 42 controls fluid flow to a spinner motor through outlet port P42. Valve 4 further includes shuttle valves 43 and 44 such that the highest pressure at the outlets of the metering devices 41 and 42 is transferred to a load sensing port LS4. Though valve 4 has been shown as having two branches, it may have further branches such as for a dispenser of liquid material.
The spreader valve 4 provides a pressure signal from the load sensing port LS4 through a load sensing line 8 to the priority valve 3 load sensing inlet port LS3.
The amount of fluid delivered to the spreader valve 4 by the priority valve 3 will 2o depend on the pressure signal received at the load sensing port LS3 from the spreader valve 4. The amount of fluid directed to the spreader valve 4 is directly proportional to the fluid pressure at the outlet of the spreader valve 4. In this way, the priority valve 3 meters the exact amount of fluid required for the operation of the spreader.
Any pressure or flow changes in the excess flow line 7 have no influence on the metering towards the outlet port CF. The correct sizing of orifices in the hydraulic circuit provide for a damping effect, thus eliminating any sudden peaks in the system that might otherwise result in 'jerky' operation.
The hydraulic circuit may further include a relief valve 31 in the load sensing line 8 that limits the pressure in the spreader valve 4 circuit. The relief valve 31 may be incorporated into the priority valve 3 as shown in figure l, or it may be a separate component.
S
A bypass line 9 with an orifice 10 between the load sensing port LS3 and a drain port T3 is provided to eliminate any possibility of leakage oil through the spreader valve 4 metering devices 41 and 42 building up pressure when the spreader valve 4 is in the OFF position. By-pass line 9 permits the use of spreader valves 4 that have no internal bleed-off for the fluid in the load-sensing line 8, which would otherwise be trapped in the load sensing line 8, maintaining higher than necessary pressure in the line between the pump 1 and the priority valve 3. Examples of spreader valves 4 that do not have bleed-off are the Vickers~ ICSV3000, and the Danfoss~ 2FFC 12 or FFLC 12 valves. A by-pass line may be incorporated in the design of the spreader valve itself such as in the 800 VALACE-2LS or in the VALACE-3LS. Figure 3 is a schematic of such a valve 40 wherein orifice 45 is connected between the load sensing line 8 and a drain port T4 internally in the valve 40.
1 S Proper sizing of the pump 1 assures that, though the spreader valve is operated on a priority basis, there is sufficient excess hydraulic fluid for the operation of the plow valve 5.
The advantages of the above hydraulic circuit are numerous. A single fixed displacement pump is the most economical power source for hydraulic systems.
The use of standard open center valves for the plow functions is another economical advantage. The load sensing priority valve supplies only the oil required for the operation of the spreader, with no excess oil flowing to the reservoir. The priority valve may incorporate a relief valve, which permits the elimination of the relief valve in the spreader valve. The complete circuit is simple and affordable.
Many makes and models of priority valves exist on the market. For instance, the Eaton~ load sensing priority valve comes in VLC, VLE and VLH Models. The Danfoss~ Models OLS40 and OLS80 are priority valves without relief valves, whereas Model OLS 160 has a relief valve incorporated. A schematic of the valve 23 is illustrated in figure 2, which will be used to describe the operation of valve 23 in the hydraulic circuit 20 in accordance with the present invention which includes the fixed displacement pump 21, the spreader load sensitive valve 24 and the plow valve 25.
The priority valve 23 is a pressure control valve that maintains priority pressure to the closed center spreader valve 24. With the spreader valve 24 OFF, flow through it is blocked and all flow through the priority valve 23 is directed out the EF-port to the plow control valve 25.
With the engine off, the spool 232 is pushed to the right by the spring 233.
The passage to the EF-port is blocked while the passage to the CRport is open causing the fluid to flow through the plow valve 25.
When the pump 21 is first started, all pump flow is routed to the spreader valve 24, which blocks the flow. With the flow blocked, the pressure increases. Pump inlet pressure is supplied through the pilot orifice 234 to the right end of the spool.
232. This causes the priority valve spool 232 to shift against the spring 233 and open the EF-port. As long as the spreader valve 24 is OFF, just enough pressure is maintained at the spreader valve 24 to keep the priority valve spool 232 shifted to the left.
The operating pressure in the plow valve 25 circuit has no effect on the operation of the priority valve 23. With the plow valve 25 in relief, the priority valve 23 will not shift until the spreader valve 24 is activated.
When the spreader is working normally, load~ensing pressure from the spreader valve 24 flows through the orifice LS-port LS23 in the priority valve 23.
The load-sensing pressure plus the spring 233 force the spool 232 to move to the right against the pilot pressure on the right end of the spool 232. This restricts flow to the plow through the EF-port while the CF-port is opened to the spreader valve 24.
The load-sensing circuit LS24/2$/LS23 is a control circuit that routes spreader pressure to the spring 233 side of the priority valve spool 232. It allows the priority valve spool 232 to sense the pressure required by the spreader through the spreader valve 24 under varying conditions.
During normal material spreading operation, oil is metered into the load-s sensing circuit through an orifice in the spreader valve 24. The priority valve 23 supplies just enough oil to the spreader valve 24 to satisfy its needs and evacuates the excess to the plow circuit EF/27/P25/25.
To limit the pressure in the spreader circuit CF/26/P24/24, a relief system to may be built into the priority valve 23 or added as a separate component as illustrated in figure 2. When the conveyor jams, pressure in the spreader circuit increases. This pressure is sensed at the LS-port LS23. When the pressure increases enough to push poppet 235 off of its seat, oil in the load-sensing circuit LS24/28/LS23 flows to return through the T-port T23. Load sensing pressure is is limited to the pressure setting of the relief valve 231.
Pressure to the spreader valve 24 (pilot pressure), which is sensed at the right end of the priority valve spool 232, continues to increase until it can move the spool 232 to the left against the load-sensing pressure plus the spring 233 force.
At this 2o time all oil flows out of the EF-port to the plow circuit EF/27/P25/25.
It is normal that cycle times of the plow circuit EF/27/P25/25 slow down when the spreader operates. Proper sizing of the pump 21 insures adequate flow to all functions under all circumstances.
The present invention provides a simple, flexible, reliable and affordable system for the operation of a material spreader when it is used simultaneously with another hydraulically driven system like a snow plow.
3o While the invention has been described according to what is presently considered to be the most practical and preferred embodiments, it must be understood that the invention is not limited to the disclosed embodiments. Those ordinarily skilled in the art will understand that various modifications and equivalent structures and functions may be made without departing from the spirit and scope of the invention as defined in the claims. Therefore, the invention as defined in the claims must be accorded the broadest possible interpretation so as to encompass all such modifications and equivalent structures and functions.
EQUIPMENT
Field of the Invention The invention relates generally to equipment for removing snow and/or ice from roadways, and more particularly to a hydraulic system for controlling the equipment spreader and plow.
Background of the Invention The operation of equipment used for plowing or scraping snow and/or ice from roads, airport runways and similar surfaces and the spreading of traction enhancing material such as sand and/or salt requires the installation of a hydraulic system that supplies power to operate the spreader and plow equipment. The usual installation includes a single gear pump that pushes hydraulic fluid through an open center valve with a power beyond connection, which is used to operate the plow functions. The power beyond is connected to the pressure inlet of the spreader valve, from where it returns to a hydraulic fluid tank or reservoir, or is partially routed to the spreader's hydraulic motors. The principal problem of this circuit is the stoppage of 2o the spreader when any plow function is operated. Other solutions have been used to remedy this problem.
Tandem pumps may be used in two completely separate hydraulic circuits.
One pump supplies the plow hydraulic functions, the other one supplies the spreader only. Simultaneous operation is rendered possible for both the plow and the spreader, but several major inconveniences remain. The system is more expensive, more complicated, requires a larger hydraulic fluid reservoir and consumes more energy.
Another solution is the use of a variable displacement piston pump that is 3o usually controlled by sensing the load. The load sensing pump works in conjunction with closed center valves that share a common pressure supply, which is the pump.
This constitutes a normal load sensing circuit, with all its usual benefits.
The main problem associated with this solution is the very high cost of load sensing valves and pumps.
Canadian Patent 1,060,757 which issued on August 21, 1979 to Larson et al is an example of various types of hydraulic circuits based on a fixed displacement pump, a variable displacement pump or a load sensing pump. In this patent, the circuits are used in power steering systems, which selectively control the flow of fluid toa steering motor and an auxiliary device through the use of a priority valve.
1o Therefore, there is a need for a hydraulic system that provides hydraulic fluid to the spreader on a priority basis in spreader/plow equipment.
Summary of the Invention The invention is directed to a hydraulic system for operating equipment for Is removing snow and/or ice from surfaces having a plow, and a spreader for spreading traction enhancing materials onto the surfaces. The hydraulic system comprises a reservoir for hydraulic fluid, a fixed displacement pump for providing hydraulic fluid from the reservoir, a priority valve having an inlet port for receiving hydraulic fluid from the pump, a first outlet port and a second outlet port, whereby the priority valve 2o is mechanically biased to direct the hydraulic fluid from the inlet port primarily to the first outlet port. The system further includes a spreader valve having an inlet port coupled to the priority valve first outlet port and one or more metering device for controlling fluid flow through the spreader valve for operating the spreader, and a plow valve having an inlet port coupled to the priority valve second outlet port and a z5 metering device for controlling fluid flow through the plow valve for operating the plow. In addition, the system has means for transferring the pressure from the priority valve first outlet port to the priority valve to oppose the mechanical bias thereby directing fluid flow to the second outlet port, means for transfernng load pressure from the spreader valve to the priority valve through a load pressure line to augment 3o the mechanical bias, such that the amount of hydraulic fluid directed from the priority valve first outlet port is proportional to the load pressure from the spreader valve, and means for bleeding fluid to the reservoir from the load pressure transferring means.
In accordance with another aspect of the invention, an orifice is connected between the load pressure line and the reservoir to bleed fluid from the load pressure transferring means. The orifice may be located in the spreader valve.
With regard to a further aspect of the invention, the system may include a relief valve connected between the priority valve and the reservoir to relieve the pressure in the load sensing line. The relief valve may be located in the priority valve.
1o In accordance with another aspect of the invention, the metering device for controlling the fluid flow through the spreader valve may be solenoid operated or mechanically operated.
With respect to another aspect of the invention, the spreader may include a conveyor and/or auger and a spinner for spreading materials, as well as a liquid material dispenser.
Other aspects and advantages of the invention, as well as the structure and operation of various embodiments of the invention, will become apparent to those ordinarily skilled in the art upon review of the following description of the invention in conjunction with the accompanying drawings.
Brief Description of the Drawings The invention will be described with reference to the accompanying drawings, wherein:
Figure 1 illustrates the hydraulic system in accordance with the present invention;
Figure 2 is a schematic of a priority valve used with the present invention;
and Figure 3 is schematic of an alternate spreader valve.
Detailed Description of the Invention The hydraulic system in accordance with the present invention is illustrated in figure 1. A fixed displacement pump 1 pumps hydraulic fluid or oil at a constant flow and variable pressure from the reservoir 2 into the inlet port P3 of a priority valve 3 where the flow is divided between the priority outlet port CF and the excess flow port EF. The priority outlet port CF is coupled to the inlet port P4 of a load sensing spreader valve 4 by line 6 while the excess flow port is coupled to the inlet port P5 of an open-centred plow valve S by line 7. For purposes of illustration, the plow valve S
is shown as a conventional three-position, four way valve. By way of example, the load sensing spreader valve 4 is shown as having a first and a second branch with metering devices 41 and 42. Metering device controls fluid flow to motor for a 1 o material transporting device such as a conveyor, an auger or a combination of both, through outlet port P41, while metering device 42 controls fluid flow to a spinner motor through outlet port P42. Valve 4 further includes shuttle valves 43 and 44 such that the highest pressure at the outlets of the metering devices 41 and 42 is transferred to a load sensing port LS4. Though valve 4 has been shown as having two branches, it may have further branches such as for a dispenser of liquid material.
The spreader valve 4 provides a pressure signal from the load sensing port LS4 through a load sensing line 8 to the priority valve 3 load sensing inlet port LS3.
The amount of fluid delivered to the spreader valve 4 by the priority valve 3 will 2o depend on the pressure signal received at the load sensing port LS3 from the spreader valve 4. The amount of fluid directed to the spreader valve 4 is directly proportional to the fluid pressure at the outlet of the spreader valve 4. In this way, the priority valve 3 meters the exact amount of fluid required for the operation of the spreader.
Any pressure or flow changes in the excess flow line 7 have no influence on the metering towards the outlet port CF. The correct sizing of orifices in the hydraulic circuit provide for a damping effect, thus eliminating any sudden peaks in the system that might otherwise result in 'jerky' operation.
The hydraulic circuit may further include a relief valve 31 in the load sensing line 8 that limits the pressure in the spreader valve 4 circuit. The relief valve 31 may be incorporated into the priority valve 3 as shown in figure l, or it may be a separate component.
S
A bypass line 9 with an orifice 10 between the load sensing port LS3 and a drain port T3 is provided to eliminate any possibility of leakage oil through the spreader valve 4 metering devices 41 and 42 building up pressure when the spreader valve 4 is in the OFF position. By-pass line 9 permits the use of spreader valves 4 that have no internal bleed-off for the fluid in the load-sensing line 8, which would otherwise be trapped in the load sensing line 8, maintaining higher than necessary pressure in the line between the pump 1 and the priority valve 3. Examples of spreader valves 4 that do not have bleed-off are the Vickers~ ICSV3000, and the Danfoss~ 2FFC 12 or FFLC 12 valves. A by-pass line may be incorporated in the design of the spreader valve itself such as in the 800 VALACE-2LS or in the VALACE-3LS. Figure 3 is a schematic of such a valve 40 wherein orifice 45 is connected between the load sensing line 8 and a drain port T4 internally in the valve 40.
1 S Proper sizing of the pump 1 assures that, though the spreader valve is operated on a priority basis, there is sufficient excess hydraulic fluid for the operation of the plow valve 5.
The advantages of the above hydraulic circuit are numerous. A single fixed displacement pump is the most economical power source for hydraulic systems.
The use of standard open center valves for the plow functions is another economical advantage. The load sensing priority valve supplies only the oil required for the operation of the spreader, with no excess oil flowing to the reservoir. The priority valve may incorporate a relief valve, which permits the elimination of the relief valve in the spreader valve. The complete circuit is simple and affordable.
Many makes and models of priority valves exist on the market. For instance, the Eaton~ load sensing priority valve comes in VLC, VLE and VLH Models. The Danfoss~ Models OLS40 and OLS80 are priority valves without relief valves, whereas Model OLS 160 has a relief valve incorporated. A schematic of the valve 23 is illustrated in figure 2, which will be used to describe the operation of valve 23 in the hydraulic circuit 20 in accordance with the present invention which includes the fixed displacement pump 21, the spreader load sensitive valve 24 and the plow valve 25.
The priority valve 23 is a pressure control valve that maintains priority pressure to the closed center spreader valve 24. With the spreader valve 24 OFF, flow through it is blocked and all flow through the priority valve 23 is directed out the EF-port to the plow control valve 25.
With the engine off, the spool 232 is pushed to the right by the spring 233.
The passage to the EF-port is blocked while the passage to the CRport is open causing the fluid to flow through the plow valve 25.
When the pump 21 is first started, all pump flow is routed to the spreader valve 24, which blocks the flow. With the flow blocked, the pressure increases. Pump inlet pressure is supplied through the pilot orifice 234 to the right end of the spool.
232. This causes the priority valve spool 232 to shift against the spring 233 and open the EF-port. As long as the spreader valve 24 is OFF, just enough pressure is maintained at the spreader valve 24 to keep the priority valve spool 232 shifted to the left.
The operating pressure in the plow valve 25 circuit has no effect on the operation of the priority valve 23. With the plow valve 25 in relief, the priority valve 23 will not shift until the spreader valve 24 is activated.
When the spreader is working normally, load~ensing pressure from the spreader valve 24 flows through the orifice LS-port LS23 in the priority valve 23.
The load-sensing pressure plus the spring 233 force the spool 232 to move to the right against the pilot pressure on the right end of the spool 232. This restricts flow to the plow through the EF-port while the CF-port is opened to the spreader valve 24.
The load-sensing circuit LS24/2$/LS23 is a control circuit that routes spreader pressure to the spring 233 side of the priority valve spool 232. It allows the priority valve spool 232 to sense the pressure required by the spreader through the spreader valve 24 under varying conditions.
During normal material spreading operation, oil is metered into the load-s sensing circuit through an orifice in the spreader valve 24. The priority valve 23 supplies just enough oil to the spreader valve 24 to satisfy its needs and evacuates the excess to the plow circuit EF/27/P25/25.
To limit the pressure in the spreader circuit CF/26/P24/24, a relief system to may be built into the priority valve 23 or added as a separate component as illustrated in figure 2. When the conveyor jams, pressure in the spreader circuit increases. This pressure is sensed at the LS-port LS23. When the pressure increases enough to push poppet 235 off of its seat, oil in the load-sensing circuit LS24/28/LS23 flows to return through the T-port T23. Load sensing pressure is is limited to the pressure setting of the relief valve 231.
Pressure to the spreader valve 24 (pilot pressure), which is sensed at the right end of the priority valve spool 232, continues to increase until it can move the spool 232 to the left against the load-sensing pressure plus the spring 233 force.
At this 2o time all oil flows out of the EF-port to the plow circuit EF/27/P25/25.
It is normal that cycle times of the plow circuit EF/27/P25/25 slow down when the spreader operates. Proper sizing of the pump 21 insures adequate flow to all functions under all circumstances.
The present invention provides a simple, flexible, reliable and affordable system for the operation of a material spreader when it is used simultaneously with another hydraulically driven system like a snow plow.
3o While the invention has been described according to what is presently considered to be the most practical and preferred embodiments, it must be understood that the invention is not limited to the disclosed embodiments. Those ordinarily skilled in the art will understand that various modifications and equivalent structures and functions may be made without departing from the spirit and scope of the invention as defined in the claims. Therefore, the invention as defined in the claims must be accorded the broadest possible interpretation so as to encompass all such modifications and equivalent structures and functions.
Claims (9)
1. In equipment for removing snow and ice from surfaces having a plow and a spreader for spreading traction enhancing materials onto the surfaces, a hydraulic system for operating the spreader and the plow comprising:
- reservoir means for hydraulic fluid;
- fixed displacement pump means for providing hydraulic fluid from the reservoir;
- priority valve means having an inlet port for receiving hydraulic fluid from the pump means, a first outlet port and a second outlet port, whereby the priority valve means is mechanically biased to direct the hydraulic fluid from the inlet port primarily to the first outlet port;
- spreader valve means having an inlet port coupled to the priority valve means first outlet port and means for controlling fluid flow through the spreader valve for operating the spreader;
- plow valve means having an inlet port coupled to the priority valve means second outlet port and means for controlling fluid flow through the plow valve means for operating the plow;
- means for transferring pressure from the priority valve means first outlet port to the priority valve means to oppose the mechanical bias thereby directing fluid flow to the second outlet port;
- means for transferring load pressure from the spreader valve means to the priority valve means through a load pressure line to augment the mechanical bias, such that the amount of hydraulic fluid directed from the priority valve means first outlet port is proportional to the load pressure from the spreader valve means; and - means for bleeding fluid to the reservoir means from the load pressure transferring means.
- reservoir means for hydraulic fluid;
- fixed displacement pump means for providing hydraulic fluid from the reservoir;
- priority valve means having an inlet port for receiving hydraulic fluid from the pump means, a first outlet port and a second outlet port, whereby the priority valve means is mechanically biased to direct the hydraulic fluid from the inlet port primarily to the first outlet port;
- spreader valve means having an inlet port coupled to the priority valve means first outlet port and means for controlling fluid flow through the spreader valve for operating the spreader;
- plow valve means having an inlet port coupled to the priority valve means second outlet port and means for controlling fluid flow through the plow valve means for operating the plow;
- means for transferring pressure from the priority valve means first outlet port to the priority valve means to oppose the mechanical bias thereby directing fluid flow to the second outlet port;
- means for transferring load pressure from the spreader valve means to the priority valve means through a load pressure line to augment the mechanical bias, such that the amount of hydraulic fluid directed from the priority valve means first outlet port is proportional to the load pressure from the spreader valve means; and - means for bleeding fluid to the reservoir means from the load pressure transferring means.
2. A hydraulic system as claimed in claim 1 wherein the means for bleeding hydraulic fluid comprises an orifice connected between the load pressure line and the reservoir means.
3. A hydraulic system as claimed in claim 2 wherein the orifice is located in the spreader valve means.
4. A hydraulic system as claimed in claim 1 which further includes a relief valve connected between the priority valve means and the reservoir means to relieve the pressure in the load pressure transferring means.
5. A hydraulic system as claimed in claim 1 wherein the means for controlling the fluid flow through the spreader valve means is a solenoid operated metering device.
6. A hydraulic system as claimed in claim 1 wherein the means for controlling the fluid flow through the spreader valve means is a mechanically operated metering device.
7. A hydraulic system as claimed in claim 1 wherein the spreader includes a conveyor, an auger and a spinner for the materials.
8. A hydraulic system as claimed in claim 1 wherein the spreader includes a conveyor or auger and a spinner for the materials.
9. A hydraulic system as claimed in claims 7 or 8 wherein the spreader includes a liquid dispensing device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2390186 CA2390186C (en) | 2002-07-02 | 2002-07-02 | Hydraulic system for a plowing and material spreading equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2390186 CA2390186C (en) | 2002-07-02 | 2002-07-02 | Hydraulic system for a plowing and material spreading equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2390186A1 CA2390186A1 (en) | 2004-01-02 |
| CA2390186C true CA2390186C (en) | 2006-01-10 |
Family
ID=30449895
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2390186 Expired - Fee Related CA2390186C (en) | 2002-07-02 | 2002-07-02 | Hydraulic system for a plowing and material spreading equipment |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2390186C (en) |
-
2002
- 2002-07-02 CA CA 2390186 patent/CA2390186C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2390186A1 (en) | 2004-01-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7431101B2 (en) | Load sensing hydraulic system | |
| US4986071A (en) | Fast response load sense control system | |
| JP3150980B2 (en) | Pressure compensation hydraulic pressure control device | |
| CA1125145A (en) | Power transmission | |
| EP0468944B1 (en) | An arrangement for controlling hydraulic motors | |
| US6715402B2 (en) | Hydraulic control circuit for operating a split actuator mechanical mechanism | |
| US6675904B2 (en) | Apparatus for controlling an amount of fluid for heavy construction equipment | |
| NZ200515A (en) | Hydraulic control system with pilot controlled meter-in valve | |
| CN103328829B (en) | There is the independent metering valve of current limiter | |
| CA2390186C (en) | Hydraulic system for a plowing and material spreading equipment | |
| US6467553B1 (en) | Hydraulic plow balancing system | |
| US4892465A (en) | Automatic control for variable displacement pump | |
| KR101011992B1 (en) | Double-circuit hydraulic system | |
| US4495766A (en) | Controls for hydrostatic systems | |
| EP2005006B1 (en) | Pilot-operated differential-area pressure compensator and control system for piloting same | |
| CA2725851C (en) | Load sensing hydraulic system | |
| GB2049814A (en) | Pumps for Hydraulic Systems | |
| EP0063025A1 (en) | Hydraulic control circuit for an hydraulic ram | |
| CA2571609C (en) | Load sensing hydraulic system | |
| JP3868730B2 (en) | Brake mechanism for self-propelled construction machinery | |
| RU2092718C1 (en) | Hydraulic drive | |
| RU2150552C1 (en) | Synchronously-controlled hydraulic system | |
| SU1521649A1 (en) | Positive displacement steering drive | |
| SU1235816A1 (en) | Hydraulic drive for crane boom | |
| RU2233572C2 (en) | Hydraulic system for tractor hitch |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20180703 |