CA1204983A - Anti-plug control - Google Patents
Anti-plug controlInfo
- Publication number
- CA1204983A CA1204983A CA000438556A CA438556A CA1204983A CA 1204983 A CA1204983 A CA 1204983A CA 000438556 A CA000438556 A CA 000438556A CA 438556 A CA438556 A CA 438556A CA 1204983 A CA1204983 A CA 1204983A
- Authority
- CA
- Canada
- Prior art keywords
- fluid
- pump
- pressure
- control
- displacement
- 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
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
- F16H61/478—Automatic regulation in accordance with output requirements for preventing overload, e.g. high pressure limitation
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01F—PROCESSING OF HARVESTED PRODUCE; HAY OR STRAW PRESSES; DEVICES FOR STORING AGRICULTURAL OR HORTICULTURAL PRODUCE
- A01F12/00—Parts or details of threshing apparatus
- A01F12/56—Driving mechanisms for the threshing parts
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01F—PROCESSING OF HARVESTED PRODUCE; HAY OR STRAW PRESSES; DEVICES FOR STORING AGRICULTURAL OR HORTICULTURAL PRODUCE
- A01F29/00—Cutting apparatus specially adapted for cutting hay, straw or the like
- A01F29/09—Details
- A01F29/14—Drives
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
- F16H61/433—Pump capacity control by fluid pressure control means
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental Sciences (AREA)
- Control Of Fluid Gearings (AREA)
- Agricultural Machines (AREA)
- Harvester Elements (AREA)
Abstract
Abstract An anti-plug control for a drive to prevent jamming of a driven working element in response to an overload wherein said drive includes a hydrostatic transmission having a variable displacement unit and a fixed displacement unit connected in closed circuit.
A servo control cylinder is connected to a swash plate of the variable displacement unit for causing position-ing thereof. A normally closed pressure-responsive valve monitors the pressure in the high pressure side of the closed circuit and is openable when the pressure reaches a predetermined value to deliver fluid from the closed circuit to the servo control cylinder and modify the displacement of the variable displacement unit to in-crease the speed of the working element to attempt clearing the overloaded condition of the working element.
A servo control cylinder is connected to a swash plate of the variable displacement unit for causing position-ing thereof. A normally closed pressure-responsive valve monitors the pressure in the high pressure side of the closed circuit and is openable when the pressure reaches a predetermined value to deliver fluid from the closed circuit to the servo control cylinder and modify the displacement of the variable displacement unit to in-crease the speed of the working element to attempt clearing the overloaded condition of the working element.
Description
~4~83 ~
Description Anti-Plug Control Technical Field This invention relates to an anti-plug con-trol for a drive which drives a working element, suchas the main rotor of a rotary combine harvester that can be jammed by excessive material. More particular-ly, the invention relates to the ~ontrol of a variable displacement unit of a hydrostatic transmission used independently as the drive means or as part of a hydromechanical transmission drive means with the change of the displacement of the variable displace-ment unit upon the occurrence of a jam effecting an increase in the speed of the working element.
Background Art In rotary ciombine harvesters, there is a driven main rotor to which the crop is fed. The main rotor can be subject to plugging which occurs when the main rotor becomes jammed with crop because the crop is fed thereto in larger quantities than can be passed by the main rotor. The control of this invention senses the pressure in the closed circuit of the hydrostatic transmission and, when the pressure reaches a predeterm;ned value, the control operates to adjust the variable displacement unit of the hydrostatic transmission to increase the speed of the main rotor. It is known in the art to sense the pres-sure in the closed circuit of a hydrostatic transmis-sion and, at some level of pressure, cause a change in the displacement of the variable displacement unit.
However, such a control has been to reduce the torque applied to the motor, rather than cause a change in the ~2e)~s3 speed of the motor of the transmission to increase the speed of the working element driven by the transmis-sion.
Disclosure of the Invention The present invention relates to a new and improved anti-plug control for a drive to prevent jamming of a driven working eIement in response to an overload by varying the displacement of the variable displacement unit of a hydrostatic transmission to increase the speed of the working element. This working element can be the main rotor of a rotary combine harvester or other conveying devices, such as a belt conveyor or an auger, which could be subject to jamming by an excess quantity of material being handled.
A primary feature o~ the invention is to pro-vide an anti-plug control for a drive utilizing a hydrostatic transmission having a variable displacement unit and fixed displacement unit in closed circuit wherein the pressure in the high pressure side of the closed circuit is monitored and, when the pressure exceeds a predetPrm;n~d value, the displacement o~ the variable displacement unit is changed to result in an increase in speed of the working element to cleax material from the working element in an effort to prevent jamming thereof.
In carrying out the foregoing, the drive i5 a hydromechanical transmission, with ~he hydrostatic transmission being part thereof, with the variable dis-placement unit having a swash plate and a servo control cylinder connected thereto. A ~luid line extends from the high pressure side of the closed circuit to said servo control cylinder and a normally closed pressure-responsive valve in the fluid line opens when said pre-determined pressure is reached and causes pressure ~Z~?4~3 fluid to act on the servo control cylinder to decrease the displacement of the variable displacement unit, with the result that the speed of the working element is increased.
An object of the invention is to provide an anti-plug control for a drive to prevent jamming of a driven working element in response to an overload wherein the drive includes a fluid motor and a variable displacement fluid pump in closed circuit for supplying fluid to the motor comprising, means for controlling displacement of the pump, means or sensing the pres-suxe of the fluid delivered by the pump to the motor, and means responsive to an increase of said pressure beyond a predetermined value for modifying the dis-placement of the pump to increase the speed of saiddrive.
Still another object of the invention is to provide a control as defined in the preceding paragraph including additional means operable in response to an increase in the fluid pressure a predetermined amount beyond said predetermined value for modifying the displacement of the pump to decrease the speed of the drive.
Still another object of the invention is to provide an anti-plug control for.a drive of the type described in the preceding paragraphs wherein the hydrostatic transmission is a part of a hydromechanical transmission. The control comprises.a fluid line connected between the high pressure side of the closed circuit and a servo control cylinder connected to a movable swash plate of the variable displacement pump, and a normally closed pressure-sensing valve in the fluid line and openable in response to a certain pressure in the high pressure side of the closed circuit to permit 12~ 3 1 fluid pressure from the closed circuit to act on the servo control cylinder and decrease pump displacement to increase the speed of the working element.
Brief Description of the Drawings Fig. 1 is a diagrammatic view o~ a hydro-mechanical transmission; and Fig. 2 is a schematic drawing of the hydro~
static components of the transmission~
Best Mode for Carrying Out the Invention Fig. 1 illustrates a conventional hydro-mechanical transmission wherein a driven input shaft 10 extends to a planetary gear set 11 and a drive shaft 12 extends from the planetary gear set, The planetary gear set typically has a sun gear and a ring gear with intermediate planet gears carried on a planet carrier.
A hydrostatic transmission having a variable displacement unit 15 and a fixed displacement unit 16 ~re connected together in a closed circuit, with the variable displace-ment unit 15 having an input shaft 17 driven by the inputshaft 10 and the fixed displacement unit having an output shaft 18 connected to an element of the planetary gear set. A hydromechanical transmission is shown in U.S.
Patent No. 3,396~607 which issued August 13, 1958 to William A. Ross. As evident from the Ross Patent, the input shaft 10 can connect to the planet gear carrier o~ the planetary gear set and the output shaft 18 o~ the fixed displacement unit connects to the ring gear and with the drive shaft 12 being connected to the sun gear. In a hydromechanical trans-mission, the speed of the planetary gear set element ~.
~2a~ss3 driven by the output shat 18 of the hydrostatic transmission can be either added or subtracted to the rotational speed of the planetary gear set element driven at a constant input speed by the input shaft 10.
With the variable displacement unit 15 at maximum displacement at one side of neutral, the speed - of the drive shaft 12 is at a ~;n;mllm and, as the displacement of the variable displacement unit 15 is decreased, the speed of the drive shaft 12 increases.
The hydrostatic transmission utili~ed in Fig. 1 is shown more particularly in Fig. 2.
The variable displacement unit 15, identified as a variable displacement pump in Fig. 2, and the fixed displacement unit 16, identified as a fixed displacement motor in Fig. 2, are each constructed as an axial piston unit, with the stroke of the pistons controlled by a swash plate.
The variable displacement pump 15 has a casing 20 which rotatably mounts on bearings the input shaft 17. A cylinder block 21 is rotatable within the casing and issplined at 22 to the input shaft for ro-tation therewith. A series of pistons 23 are movable in cylinders within the cylinder block and the stroke thereo~ is controlled by a movable swash plate 24 with shoes carried by the pistons in sliding contact with the swash plate.
The fixed displacement motor 16 has a casing 30 which rotatably mounts the output shaft 18 on bearings and a cylinder block 31 is splined at 32 to the output shaft. ~he cylinder block 31 has cylinders in each of which a piston 33 is movable with the stroke thereof being controlled by a fixed swash plate 34.
With the pump swash plate 24 positioned as shown in Fig. 2, pistons 23 are stroked for m~; mllm displacement during rotation of the cylinder block and fluid under pressure is delivered from a pump outlet 40 to a fluid line connection 41 extending to the motor 16 and which forms the high pressure side o:E
a closed circuit connecting the pump and motor. The low - pressure side of the closed circuit is through a fluid line connection 42 whereby fluid can return from the motor to the inlet of the pump. This structure is con-ventional and the conventional structure further in-cludes a charge pressure circuit including a charge pump 45 which draws fluid ~rom a reservoir 46 which passes through a filter 47. The charge pump 45 functions to provide make-up fluid to the closed circuit between the pump and motor by supply to the low pressure side through either of the charge check valves 43 and 49which, at their upstream ends, are connected to a fluid line 50 connected to the outlet side of the charge pump and, at their downstream ends are connected to the fluid line connections 41 and 42, respectively. A charge relief valve 51 operates to relieve the charge pressure when it exceeds the setting of the charge relief valve. The reservoir 46 is supplied from fluid within the casing of the motor 16 through a line 52 ~hich extends to the reservoir 46 and has a heat exchanger 53 therein for cooling the ~luid, such as oil.
Another conventional part of a hydrostatic transmission is the displacement control which includes a control valve, indicated generally at 55, and which is supplied with charge pressure fluid through the line 50. The displacement control valve 55 is posi-tiona~le to control the fluid connections of a pair of servo control cylinders 56 and 57 mounted in the pump 3LZ~ 3 casing 20 and which, through pivotally connected links 58 and 59 extended to the swash plate 24, control.the position of the swash plate.
Displacement control valve 55 has a movable valve member 60 which controls communication of the servo control cylinders with either a charge pressure port or tank ports at the displacement control valve.. More particularly, servo control cylinder 56 is connected to a port of the displacement control va~ve by lines 61 and 62 and the servo control cylinder 57 is connected to a port of the displacement control valve by lines 63 and 64.
The displacement of the swa.sh plate 24 is established by initially setting a position of the displacement control valve ~emher.60 which, as shown, can be under the control o~ a handle 68 which is pivotally mounted and which, through linkage, is con-nected to ~he valve member. In the use of the variable displacement pump as part of the hydromechanical transmission for the purposes described herein, only the servo control cylinder 56 need be used to position the swash plate 24 since only one side of the hydro-static closed circuit is pressurized throughout the speed range of the working element driven by the transmission and the internal forces within the variable displacement unit always tend to tilt the swash plate toward a clock-wise extreme position. As the handle 68 is pivoted from the position shown in a direction to shift the valve member toward the left, as viewed in Fig. 2, charge pressure is delivered through lines:61 and62 to the servo control cylinder 56, acting to extend the piston within the cylinder and thereby move the swash plate from the maximum displacement position shown towards a reduced displacement position. The linkage interconnecting the handle 68 and the valve member 60 includes a feedhack linkage connected to the swash plate whereby the valve member is caused to return to a posi-tion where lands of the valve member block the servo - control cylinder 56 from both charge pressure and a tank port at the displacement control valve. This feedback linkage includes a link 70 pivotally connected to an end of the valve member and having pivot con-nections to links 71 and 72 which pivotally connect to the handle 68 and the swash plate, respectively.
With the swash plate 24 positioned as shown in Fig. 2, the pump is at maximum displacement and thereby the motor 16 is operating at maximum speed.
Within the planetary gear set 11 there is a maximum subtraction of speed rom the input speed derived from the input shaft 10 whereby the drive shaft 12 is ro-tating at minimum speed and, in fact, could be non-rotating. As the swash plate is caused to move from maximum displacement toward zero displacement position, the speed of the motor 16 is reduced with the resulting increase in speed of the drive shaft 12.
With the drive shaft 12 driving a main rotor in a rotary combine harvester, or driving some other working element which can become overloaded, there is an increase in pressure in the high pressure side of the closed circuit between the pump and motor when overloading occurs. Means for sensing the pressureon the high pressure side comprises a pressure limiter sensing valve 75 which is normally closed by having a valve member spring-urged to a closed position to close a ~luid line 76 connected to the fluid outlet 40 of the ~æ~ 3 _9_ pump and which has a section 77 extending to the line 61 connected to the servo control cylinder 56. The pres-sure limiter sensing valve can either be pre-set or remotely selectively set to open at a predetermined value of pressure in the fluid line connection 41 between the pump and motor and, when opened, high pressure fluid is directed to the servo control cylin-der 56. This results in moving the swash plate 24 to a reduced displacement position whereby the speed of the motor output shaft 18 reduces and the speed of the drive shaft 12 from the planetary gear set increases.
For illustrative purposes, the predetermined value or level of the pressure at which the pressure limiter sensing valve 75 will open can be 5,000 psi. If the increase in speed of the drive shaft 12 is sufficient to discharge the excess material from the workingelement, the pressure in the closed circuit will ultimately re-duce and the hydrostatic transmission will return to the speed of operation set by the displacement control valve 55.
In the unlikely event that the working element is unable to discharge excess material and the working element does jam, then the pressure limiter sensing valve 80, which is set to open at a pressure higher than the pressure limiter sensing valve 75, will open.
This valve has an inlet connected to the pump outlet 40 by a line 81 and an outlet connected by a line 82 to a line 83 which connects to the servo control cylinder 57. Each of the pressure limiter sensing valves 75 and 80 are of the type having a valve member urged to a closed position by a spring and with the force of the spring being settable to control the pressur~ at which the valve will open. The pressure limiter sensing valves can be of a type which can be remotely adjustable, When the pressure limiter sensing valve B0 opensO the swash plate 24 moves to a maximum displacement posi-tion, with the result that the drive shaft 12 stops rotation. An optionally usable orifice 85 in the line 76 can be used to insure that pressure limiter sensing valve 80 will be e~fective to override the operation of the pressure limiter sensing valve 75O
Commonly mounted pressure limiter check valves 90 and 91 have their downstream sides connected to the charge pressure line 50 and their upstream ènds connected to the lines 77 and 63, respectively~ whereby the pres-sure in either of the latter lines in excess of the setting of a spring connecting the valve members 90 and ~1 and charge pressure acting on the back side of the valve members will cause a valve member to open to dis-charge fluid to the charge pressure line 50.
If the working element, such as the main rotor o a rotary combine harvester,is driven by a hydrostatic transmission,output to the rotor is usually via reduction gearing rather than by a hydromechani.cal transmission. The same control can be used since the main rotor nor~ y operates in cne direction only and one side of ~he main hydrostatic loop is pressurizedO In such control in a hydrostatic transmission, the pressure-limiter sensing valve 75 when opened would cause delivery of fluid pressure to the ~ervo control cylin-der which would act ~o move the swash plate to increase the displacement of the pump and thereby increase the speed of the motor 160 The pressure limiter sensin~
valv~ 80 would b~ connected to the servo control cylindex which, when ac~ivated~ would move the swash plate to a zero displacement position.
. ,~
Industrial applicability With the anti-plug control disclosed herein, pressure in the closed circuit of a hydrostatic transmlssion can be sensed when a working element becomes overloaded and the hydrostatic transmission adjusted in response to an increase in pressure in the closed circuit of the hydrostatic transmission to in-crease the speed of the drive of the working element in an effort to clear the overload of material and prevent a jam.
Description Anti-Plug Control Technical Field This invention relates to an anti-plug con-trol for a drive which drives a working element, suchas the main rotor of a rotary combine harvester that can be jammed by excessive material. More particular-ly, the invention relates to the ~ontrol of a variable displacement unit of a hydrostatic transmission used independently as the drive means or as part of a hydromechanical transmission drive means with the change of the displacement of the variable displace-ment unit upon the occurrence of a jam effecting an increase in the speed of the working element.
Background Art In rotary ciombine harvesters, there is a driven main rotor to which the crop is fed. The main rotor can be subject to plugging which occurs when the main rotor becomes jammed with crop because the crop is fed thereto in larger quantities than can be passed by the main rotor. The control of this invention senses the pressure in the closed circuit of the hydrostatic transmission and, when the pressure reaches a predeterm;ned value, the control operates to adjust the variable displacement unit of the hydrostatic transmission to increase the speed of the main rotor. It is known in the art to sense the pres-sure in the closed circuit of a hydrostatic transmis-sion and, at some level of pressure, cause a change in the displacement of the variable displacement unit.
However, such a control has been to reduce the torque applied to the motor, rather than cause a change in the ~2e)~s3 speed of the motor of the transmission to increase the speed of the working element driven by the transmis-sion.
Disclosure of the Invention The present invention relates to a new and improved anti-plug control for a drive to prevent jamming of a driven working eIement in response to an overload by varying the displacement of the variable displacement unit of a hydrostatic transmission to increase the speed of the working element. This working element can be the main rotor of a rotary combine harvester or other conveying devices, such as a belt conveyor or an auger, which could be subject to jamming by an excess quantity of material being handled.
A primary feature o~ the invention is to pro-vide an anti-plug control for a drive utilizing a hydrostatic transmission having a variable displacement unit and fixed displacement unit in closed circuit wherein the pressure in the high pressure side of the closed circuit is monitored and, when the pressure exceeds a predetPrm;n~d value, the displacement o~ the variable displacement unit is changed to result in an increase in speed of the working element to cleax material from the working element in an effort to prevent jamming thereof.
In carrying out the foregoing, the drive i5 a hydromechanical transmission, with ~he hydrostatic transmission being part thereof, with the variable dis-placement unit having a swash plate and a servo control cylinder connected thereto. A ~luid line extends from the high pressure side of the closed circuit to said servo control cylinder and a normally closed pressure-responsive valve in the fluid line opens when said pre-determined pressure is reached and causes pressure ~Z~?4~3 fluid to act on the servo control cylinder to decrease the displacement of the variable displacement unit, with the result that the speed of the working element is increased.
An object of the invention is to provide an anti-plug control for a drive to prevent jamming of a driven working element in response to an overload wherein the drive includes a fluid motor and a variable displacement fluid pump in closed circuit for supplying fluid to the motor comprising, means for controlling displacement of the pump, means or sensing the pres-suxe of the fluid delivered by the pump to the motor, and means responsive to an increase of said pressure beyond a predetermined value for modifying the dis-placement of the pump to increase the speed of saiddrive.
Still another object of the invention is to provide a control as defined in the preceding paragraph including additional means operable in response to an increase in the fluid pressure a predetermined amount beyond said predetermined value for modifying the displacement of the pump to decrease the speed of the drive.
Still another object of the invention is to provide an anti-plug control for.a drive of the type described in the preceding paragraphs wherein the hydrostatic transmission is a part of a hydromechanical transmission. The control comprises.a fluid line connected between the high pressure side of the closed circuit and a servo control cylinder connected to a movable swash plate of the variable displacement pump, and a normally closed pressure-sensing valve in the fluid line and openable in response to a certain pressure in the high pressure side of the closed circuit to permit 12~ 3 1 fluid pressure from the closed circuit to act on the servo control cylinder and decrease pump displacement to increase the speed of the working element.
Brief Description of the Drawings Fig. 1 is a diagrammatic view o~ a hydro-mechanical transmission; and Fig. 2 is a schematic drawing of the hydro~
static components of the transmission~
Best Mode for Carrying Out the Invention Fig. 1 illustrates a conventional hydro-mechanical transmission wherein a driven input shaft 10 extends to a planetary gear set 11 and a drive shaft 12 extends from the planetary gear set, The planetary gear set typically has a sun gear and a ring gear with intermediate planet gears carried on a planet carrier.
A hydrostatic transmission having a variable displacement unit 15 and a fixed displacement unit 16 ~re connected together in a closed circuit, with the variable displace-ment unit 15 having an input shaft 17 driven by the inputshaft 10 and the fixed displacement unit having an output shaft 18 connected to an element of the planetary gear set. A hydromechanical transmission is shown in U.S.
Patent No. 3,396~607 which issued August 13, 1958 to William A. Ross. As evident from the Ross Patent, the input shaft 10 can connect to the planet gear carrier o~ the planetary gear set and the output shaft 18 o~ the fixed displacement unit connects to the ring gear and with the drive shaft 12 being connected to the sun gear. In a hydromechanical trans-mission, the speed of the planetary gear set element ~.
~2a~ss3 driven by the output shat 18 of the hydrostatic transmission can be either added or subtracted to the rotational speed of the planetary gear set element driven at a constant input speed by the input shaft 10.
With the variable displacement unit 15 at maximum displacement at one side of neutral, the speed - of the drive shaft 12 is at a ~;n;mllm and, as the displacement of the variable displacement unit 15 is decreased, the speed of the drive shaft 12 increases.
The hydrostatic transmission utili~ed in Fig. 1 is shown more particularly in Fig. 2.
The variable displacement unit 15, identified as a variable displacement pump in Fig. 2, and the fixed displacement unit 16, identified as a fixed displacement motor in Fig. 2, are each constructed as an axial piston unit, with the stroke of the pistons controlled by a swash plate.
The variable displacement pump 15 has a casing 20 which rotatably mounts on bearings the input shaft 17. A cylinder block 21 is rotatable within the casing and issplined at 22 to the input shaft for ro-tation therewith. A series of pistons 23 are movable in cylinders within the cylinder block and the stroke thereo~ is controlled by a movable swash plate 24 with shoes carried by the pistons in sliding contact with the swash plate.
The fixed displacement motor 16 has a casing 30 which rotatably mounts the output shaft 18 on bearings and a cylinder block 31 is splined at 32 to the output shaft. ~he cylinder block 31 has cylinders in each of which a piston 33 is movable with the stroke thereof being controlled by a fixed swash plate 34.
With the pump swash plate 24 positioned as shown in Fig. 2, pistons 23 are stroked for m~; mllm displacement during rotation of the cylinder block and fluid under pressure is delivered from a pump outlet 40 to a fluid line connection 41 extending to the motor 16 and which forms the high pressure side o:E
a closed circuit connecting the pump and motor. The low - pressure side of the closed circuit is through a fluid line connection 42 whereby fluid can return from the motor to the inlet of the pump. This structure is con-ventional and the conventional structure further in-cludes a charge pressure circuit including a charge pump 45 which draws fluid ~rom a reservoir 46 which passes through a filter 47. The charge pump 45 functions to provide make-up fluid to the closed circuit between the pump and motor by supply to the low pressure side through either of the charge check valves 43 and 49which, at their upstream ends, are connected to a fluid line 50 connected to the outlet side of the charge pump and, at their downstream ends are connected to the fluid line connections 41 and 42, respectively. A charge relief valve 51 operates to relieve the charge pressure when it exceeds the setting of the charge relief valve. The reservoir 46 is supplied from fluid within the casing of the motor 16 through a line 52 ~hich extends to the reservoir 46 and has a heat exchanger 53 therein for cooling the ~luid, such as oil.
Another conventional part of a hydrostatic transmission is the displacement control which includes a control valve, indicated generally at 55, and which is supplied with charge pressure fluid through the line 50. The displacement control valve 55 is posi-tiona~le to control the fluid connections of a pair of servo control cylinders 56 and 57 mounted in the pump 3LZ~ 3 casing 20 and which, through pivotally connected links 58 and 59 extended to the swash plate 24, control.the position of the swash plate.
Displacement control valve 55 has a movable valve member 60 which controls communication of the servo control cylinders with either a charge pressure port or tank ports at the displacement control valve.. More particularly, servo control cylinder 56 is connected to a port of the displacement control va~ve by lines 61 and 62 and the servo control cylinder 57 is connected to a port of the displacement control valve by lines 63 and 64.
The displacement of the swa.sh plate 24 is established by initially setting a position of the displacement control valve ~emher.60 which, as shown, can be under the control o~ a handle 68 which is pivotally mounted and which, through linkage, is con-nected to ~he valve member. In the use of the variable displacement pump as part of the hydromechanical transmission for the purposes described herein, only the servo control cylinder 56 need be used to position the swash plate 24 since only one side of the hydro-static closed circuit is pressurized throughout the speed range of the working element driven by the transmission and the internal forces within the variable displacement unit always tend to tilt the swash plate toward a clock-wise extreme position. As the handle 68 is pivoted from the position shown in a direction to shift the valve member toward the left, as viewed in Fig. 2, charge pressure is delivered through lines:61 and62 to the servo control cylinder 56, acting to extend the piston within the cylinder and thereby move the swash plate from the maximum displacement position shown towards a reduced displacement position. The linkage interconnecting the handle 68 and the valve member 60 includes a feedhack linkage connected to the swash plate whereby the valve member is caused to return to a posi-tion where lands of the valve member block the servo - control cylinder 56 from both charge pressure and a tank port at the displacement control valve. This feedback linkage includes a link 70 pivotally connected to an end of the valve member and having pivot con-nections to links 71 and 72 which pivotally connect to the handle 68 and the swash plate, respectively.
With the swash plate 24 positioned as shown in Fig. 2, the pump is at maximum displacement and thereby the motor 16 is operating at maximum speed.
Within the planetary gear set 11 there is a maximum subtraction of speed rom the input speed derived from the input shaft 10 whereby the drive shaft 12 is ro-tating at minimum speed and, in fact, could be non-rotating. As the swash plate is caused to move from maximum displacement toward zero displacement position, the speed of the motor 16 is reduced with the resulting increase in speed of the drive shaft 12.
With the drive shaft 12 driving a main rotor in a rotary combine harvester, or driving some other working element which can become overloaded, there is an increase in pressure in the high pressure side of the closed circuit between the pump and motor when overloading occurs. Means for sensing the pressureon the high pressure side comprises a pressure limiter sensing valve 75 which is normally closed by having a valve member spring-urged to a closed position to close a ~luid line 76 connected to the fluid outlet 40 of the ~æ~ 3 _9_ pump and which has a section 77 extending to the line 61 connected to the servo control cylinder 56. The pres-sure limiter sensing valve can either be pre-set or remotely selectively set to open at a predetermined value of pressure in the fluid line connection 41 between the pump and motor and, when opened, high pressure fluid is directed to the servo control cylin-der 56. This results in moving the swash plate 24 to a reduced displacement position whereby the speed of the motor output shaft 18 reduces and the speed of the drive shaft 12 from the planetary gear set increases.
For illustrative purposes, the predetermined value or level of the pressure at which the pressure limiter sensing valve 75 will open can be 5,000 psi. If the increase in speed of the drive shaft 12 is sufficient to discharge the excess material from the workingelement, the pressure in the closed circuit will ultimately re-duce and the hydrostatic transmission will return to the speed of operation set by the displacement control valve 55.
In the unlikely event that the working element is unable to discharge excess material and the working element does jam, then the pressure limiter sensing valve 80, which is set to open at a pressure higher than the pressure limiter sensing valve 75, will open.
This valve has an inlet connected to the pump outlet 40 by a line 81 and an outlet connected by a line 82 to a line 83 which connects to the servo control cylinder 57. Each of the pressure limiter sensing valves 75 and 80 are of the type having a valve member urged to a closed position by a spring and with the force of the spring being settable to control the pressur~ at which the valve will open. The pressure limiter sensing valves can be of a type which can be remotely adjustable, When the pressure limiter sensing valve B0 opensO the swash plate 24 moves to a maximum displacement posi-tion, with the result that the drive shaft 12 stops rotation. An optionally usable orifice 85 in the line 76 can be used to insure that pressure limiter sensing valve 80 will be e~fective to override the operation of the pressure limiter sensing valve 75O
Commonly mounted pressure limiter check valves 90 and 91 have their downstream sides connected to the charge pressure line 50 and their upstream ènds connected to the lines 77 and 63, respectively~ whereby the pres-sure in either of the latter lines in excess of the setting of a spring connecting the valve members 90 and ~1 and charge pressure acting on the back side of the valve members will cause a valve member to open to dis-charge fluid to the charge pressure line 50.
If the working element, such as the main rotor o a rotary combine harvester,is driven by a hydrostatic transmission,output to the rotor is usually via reduction gearing rather than by a hydromechani.cal transmission. The same control can be used since the main rotor nor~ y operates in cne direction only and one side of ~he main hydrostatic loop is pressurizedO In such control in a hydrostatic transmission, the pressure-limiter sensing valve 75 when opened would cause delivery of fluid pressure to the ~ervo control cylin-der which would act ~o move the swash plate to increase the displacement of the pump and thereby increase the speed of the motor 160 The pressure limiter sensin~
valv~ 80 would b~ connected to the servo control cylindex which, when ac~ivated~ would move the swash plate to a zero displacement position.
. ,~
Industrial applicability With the anti-plug control disclosed herein, pressure in the closed circuit of a hydrostatic transmlssion can be sensed when a working element becomes overloaded and the hydrostatic transmission adjusted in response to an increase in pressure in the closed circuit of the hydrostatic transmission to in-crease the speed of the drive of the working element in an effort to clear the overload of material and prevent a jam.
Claims (10)
1. An anti plug control for a drive to prevent jamming of a driven working element in response to an overload wherein said drive includes a fluid motor and a variable displacement fluid pump for supplying fluid under pressure to the motor comprising, servo means for controlling dis-placement of the pump, sensing means for sensing the pressure of the fluid delivered by the pump to the motor, said sensing means being responsive to an increase of fluid pressure beyond a predetermined value for modifying the displacement of said pump to increase the speed of said drive, and said sensing means being operable in response to an increase in the fluid pressure of predetermined amount beyond said predetermined value for modifying the displacement of the pump to decrease the speed of the drive.
2. A control as defined in claim 1 wherein said sensing means is operable to stop said drive.
3. A control as defined in claim 1 wherein said servo means comprises a pair of servo control cylinders and said sensing means includes a first fluid line extended between the pump outlet and one of said servo control cylinders and a first normally closed pressure-responsive valve in said first fluid line and openable when said fluid pressure reaches said predetermined value.
4. A control as defined in claim 3 wherein said sensing means includes a second fluid line between the pump outlet and the other of said servo cylinders and a second normally closed pressure-responsive valve in said second fluid line set to open at a fluid pressure value higher than said predetermined value.
5. A control as defined in claim 4 wherein said fluid lines from the pump outlet are interconnected and an orifice is in the fluid line to said one servo control cylinder to insure flow to the other servo control cylinder when the second pressure-responsive valve opens.
6. A control as defined in claim 1 wherein said servo means includes a pair of servo control cylinders positioning a pump swashplate and a pair of fluid lines connected to the pump outlet and connected one to each of said servo control cylinders, and said sensing means include a pair of normally closed pressure-responsive valves positioned one in each of said fluid lines for blocking fluid flow to said servo control cylinders, said pressure-responsive valves being openable at different values of pressure at said pump outlet whereby said swashplate is urged in one direction when one valve opens and in an opposite direction when the other valve opens.
7. A control as defined in claim 1 wherein said drive is a hydromechanical transmission, said variable dis-placement pump being at maximum displacement when said drive is at minimum speed and the displacement of said variable displacement pump being decreased when the fluid pressure exceeds said predetermined value to decrease the speed of said motor and increase the speed of the drive.
8. A control as defined in claim 7 wherein said sensing means includes a first valve which opens to deliver fluid from said pump outlet to a servo control cylinder reducing pump displacement.
9. A control as defined in claim 7 including means operable when the fluid pressure substantially exceeds said predetermined value by said predetermined amount to increase the displacement of said pump which increases the speed of said motor and reduce the speed of said drive.
10. A control as defined in claim 9 wherein said sensing means includes a second valve which opens to deliver fluid from said pump outlet to a second servo cylinder to increase pump displacement.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US44940782A | 1982-12-13 | 1982-12-13 | |
| US449,407 | 1982-12-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1204983A true CA1204983A (en) | 1986-05-27 |
Family
ID=23784051
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000438556A Expired CA1204983A (en) | 1982-12-13 | 1983-10-06 | Anti-plug control |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS59113826A (en) |
| CA (1) | CA1204983A (en) |
| DE (1) | DE3344869A1 (en) |
| FR (1) | FR2537386B1 (en) |
| GB (1) | GB2131920B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19632977B4 (en) * | 1996-08-16 | 2009-04-02 | Claas Kgaa Mbh | Device and method for intake control of a forage harvester |
| EP0914764A1 (en) * | 1997-11-04 | 1999-05-12 | Agco Corporation | Combine harvester rotor speed control and control method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1301792A (en) * | 1961-09-27 | 1962-08-17 | Inst Leichtbau Und Okonomische | Hydraulic control system, especially for vehicles |
| US3248913A (en) * | 1964-03-12 | 1966-05-03 | Emerson Electric Co | Torque and speed responsive system |
| US3396607A (en) * | 1966-02-21 | 1968-08-13 | Sundstrand Corp | Hydrostatic transmission |
| FR2037306A5 (en) * | 1970-01-09 | 1970-12-31 | Applic Mach Motrices | |
| DE2204849A1 (en) * | 1972-02-02 | 1973-08-09 | Weserhuette Ag Eisenwerk | HYDRAULIC CIRCUIT FOR LOW-LOSS PRESSURE LIMITATION FOR OPEN, SEMI-OPEN AND CLOSED HYDRAULIC CIRCUITS |
| CH590086A5 (en) * | 1976-04-14 | 1977-07-29 | Cyphelly Ivan J | |
| DE2817484A1 (en) * | 1978-04-21 | 1979-10-31 | Linde Ag | Variable volume hydraulic pump - has operating lever with piston in cylinder with drain valve shut=off set by output pressure |
| FR2426816A2 (en) * | 1978-05-24 | 1979-12-21 | Eaton Corp | Electrohydraulic controller for hydrostatic transmission - has devices biassing valve spool toward positions porting fluid to standard controller and from manual controller respectively |
-
1983
- 1983-10-06 CA CA000438556A patent/CA1204983A/en not_active Expired
- 1983-11-02 FR FR8317384A patent/FR2537386B1/en not_active Expired
- 1983-12-08 GB GB08332758A patent/GB2131920B/en not_active Expired
- 1983-12-12 JP JP23291483A patent/JPS59113826A/en active Pending
- 1983-12-12 DE DE19833344869 patent/DE3344869A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB8332758D0 (en) | 1984-01-18 |
| FR2537386B1 (en) | 1987-05-07 |
| GB2131920A (en) | 1984-06-27 |
| GB2131920B (en) | 1986-03-12 |
| JPS59113826A (en) | 1984-06-30 |
| DE3344869A1 (en) | 1984-06-14 |
| FR2537386A1 (en) | 1984-06-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |