WO2006089863A1 - A compensating coupling in the control of a motor - Google Patents

A compensating coupling in the control of a motor Download PDF

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Publication number
WO2006089863A1
WO2006089863A1 PCT/EP2006/060064 EP2006060064W WO2006089863A1 WO 2006089863 A1 WO2006089863 A1 WO 2006089863A1 EP 2006060064 W EP2006060064 W EP 2006060064W WO 2006089863 A1 WO2006089863 A1 WO 2006089863A1
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WO
WIPO (PCT)
Prior art keywords
pressure
valve
motor
line
pressure difference
Prior art date
Application number
PCT/EP2006/060064
Other languages
French (fr)
Inventor
Arto Alfthan
Original Assignee
John Deere Forestry Oy
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by John Deere Forestry Oy filed Critical John Deere Forestry Oy
Publication of WO2006089863A1 publication Critical patent/WO2006089863A1/en
Priority to SE0602042A priority Critical patent/SE529574C2/en

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Classifications

    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/042—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in"
    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • 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
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. 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
    • F15B2211/40—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
    • F15B2211/40553—Flow control characterised by the type of flow control means or valve with pressure compensating valves
    • F15B2211/40561—Flow control characterised by the type of flow control means or valve with pressure compensating valves the pressure compensating valve arranged upstream of the flow control means
    • 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
    • F15B2211/46—Control of flow in the return line, i.e. meter-out 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members

Definitions

  • the invention relates to a pressurized medium circuit according to claim 1 for controlling a motor irrespective of the loading.
  • the invention relates to a method according to claim 6 in a pressurized medium circuit, for controlling a motor irrespective of the loading.
  • the invention relates to the use of a pressurized medium circuit according to claim 10 for controlling the motor of a fan in a forest machine, irrespective of the loading.
  • Control valves such as proportionally controlled directional valves, are used for supplying a desired volume flow to an actuator operating against a positive load in the normal situation but, depending on the structure or other construction of the mechanisms to be controlled, often also against a negative load (so-called escaping load).
  • the control valves operate on various principles; for example, they have a valve spool that opens and closes valve ports and affects the internal flow resistance of the valve that causes a pressure loss in the medium passing through the valve.
  • the pressurized medium is choked when it flows over the edge of the valve spool, and simultaneously pressure losses are caused, forming a pressure difference e.g. between the input and output ports, that is, the pressure difference of the valve. If the valve spool does not move, the quantity of the volume flow will depend on the pressure difference effective over the control valve. This pressure difference is effected by the feeding pressure of the medium, generated in a pump of the system or maintained in the feeding line, and the loading of the actuator, whose effect is reflected in the pressure line to the actuator.
  • EP 0 008 523 presents a method applying the compensation of the return line (meter-out), wherein the pressure difference of the directional valve in the return line is monitored by a compensator in the return line.
  • the compensator chokes the return flow, if a pressure increase occurs in the line from the actuator.
  • document EP 1 355 065 A1 discloses a compensation arranged in the return line to monitor the pressure difference developing in the directional valve during the operation. Said directional valve is in the return line and is effective on the volume flow from the actuator.
  • EP 0 809 737 B1 teaches the implementation of a so-called meter- out compensation by controlling the choke of the return line in the situation of an escaping load.
  • the choke is used in the inlet line of the actuator to maintain a desired pressure level for the actuator.
  • the aim of the pressurized medium circuit according to the invention is to control the operation of the motor used as an actuator and particularly to slow down and stop it by reducing the risk of cavitation.
  • a particular application is apparatuses for cutting and delimbing of tree trunks, known as such, for example harvester heads in forest machines.
  • a chain saw is applied in these apparatuses.
  • the forest machines include harvesters.
  • a particular application is also the condensing apparatuses of forest machines, in which the present pressurized medium circuit is applied for controlling the fan motor. The mass of the fan blades coupled to the motor tends to maintain the motion also in a stopping
  • the presented circuit is used to prevent cavitation.
  • the fan blades are coupled by means of, for example, a belt to the power transmission shaft of the forest machine, but by using the present circuit, it is possible to control the fan motor irrespective of the speed of rotation of the power transmission shaft.
  • the forest machines include particularly harvesters for processing tree trunks and machines for transporting the tree trunks, or combinations of these.
  • the pressurized medium circuit according to the invention is characterized by the features presented in claim 1.
  • the method according to the invention is characterized by the features presented in claim 6.
  • the use according to the invention is characterized by the features presented in claim 10.
  • Other embodiments of the invention will be disclosed in the other claims.
  • Fig. 1 shows a first embodiment of the invention and the principle of operation of the pressurized medium circuit with its components and couplings, and
  • Fig. 2 shows a second embodiment of invention.
  • a pressurized medium circuit 1 comprises a pressure or inlet line P for the incoming pressurized medium, to be coupled to the pressure line of, for example, a forest machine or a harvester head.
  • the pressurized medium is particularly a hydraulic fluid.
  • the return line T is coupled to the return or tank line of the forest machine or harvester head, to which the medium is returned after it has passed through the actuator M, which is a motor known as such.
  • the motor is the saw motor of a harvester head or the like that rotates a chain saw 10 for cutting a tree trunk, in a way known as such.
  • the motor M is coupled between the connection MT of the return line T and the connection MP of the pressure line P.
  • the volume flow determines the speed of rotation of the motor M, and the pressure difference between the connection MT and the connection MP determines the torque of the motor M.
  • a control valve 3 is coupled in series with the motor M in the pressure line P.
  • it is a proportionally operating choke implemented by a pilot- controlled or direct-controlled, normally closed 2/2 directional valve.
  • the valve has a closed position and an open position.
  • the valve 3 comprises a control line 2 (connection X) effective on the position of the valve stem (or spool) and equipped with a choke 8, and the pressure of the medium in the control line 2 determines the position of the stem and thereby also the internal flow resistance of the valve 3.
  • the pressure difference effective over the valve 3 determines the volume flow and the speed of the motor M. Consequently, the control pressure of the control line 2 is used to determine the internal flow resistance of the valve 3 and further the desired volume flow.
  • the control pressure opens the valve 3 and acts against a spring.
  • the motor M is coupled to the connection MP located after the valve 3 in the pressure line P, and to the connection MT located before a valve 4 in a tank line T.
  • the references MP and MT also refer to the line between said connection and the respective valve.
  • control line 2 instead of the pressure control of the control line 2, it is also possible to use electrical control, wherein the position of the stem of the valve 3 is affected by a proportionally operating electric magnet, by using pilot control, if necessary.
  • the volume flow is determined by the control signal that controls the magnet.
  • the control signal is obtained from the control system of the forest machine.
  • a control valve 4 is coupled in series with the motor M in the return line T, and in this case, it is a proportionally operating choke implemented by a normally open 2/2 valve.
  • the valve has an open position and a position in which the medium is choked, wherein a suitable counterpressure is produced in the return line MT, if necessary, when the pressure in the return line T is low.
  • the valve 4 (meter-out, valve after the actuator) operates as a pressure compensator for the valve 3 (meter-in, valve before the actuator), for maintaining a constant pressure difference over the valve 3.
  • the pressure compensator 4 By placing the pressure compensator 4 in the return line T and the valve 3 in the pressure line P, it is possible to control both the positive load and the negative load (i.e. overspeeding motor) of the motor M.
  • the valve 4 comprises a first control line 5 (equipped with a choke 9) and a second control line 7, which are effective on the position of the valve stem, and the pressure difference between the control lines determines the position of the stem and the internal flow resistance of the valve 4.
  • the internal flow resistance of the valve 4 and the volume flow from the motor M determine the pressure difference effective over the valve 4 and simultaneously the level of the counterpressure effective on the operation of the motor M in the line MT (the pressure in the return line T being low).
  • the difference between the control pressures of the control lines 5 and 7 is effective on the pressure level in the line MT.
  • the pressure of the first control line 5 closes the valve 4 and acts against a spring.
  • the second control line 7 has a reverse effect on the stem and tends to open the valve 4.
  • the counterpressure caused by the valve 4 in the line MT also affects the pressure level in the line MP and particularly the pressure difference over the valve 3, which is to be kept constant.
  • the pressure difference in the valve 4 is decreased/increased in a way inversely proportional to the loading of the motor M, which, in turn, has an effect on the pressure in the line MP.
  • the pressure difference effective over the valve 4 decreases/increases in a way directly proportional to the change in the pressure difference in the valve 3.
  • the pressure compensator 4 is coupled to the return line T, downstream (meter-out) with respect to the motor M used as the actuator, and the valve 3 is coupled in the pressure line P, upstream (meter- in) with respect to the motor M used as the actuator, wherein the actuator is placed between the valves 3 and 4.
  • the valve 3 is not used for choking the medium in the return line T.
  • the pressure compensator 4 is used for controlling the pressure difference effective over the valve 3. The prevailing pressures are monitored by means of the control lines 5 and 7 which, in turn, control the flow resistance of the pressure compensator 4 and the pressure difference developed in the pressure compensator 4.
  • the pressurized medium circuit of Fig. 1 is preferably integrated in the rest of the pressurized medium circuit of the harvester head, implemented, for example, as a valve block provided with the necessary components and control lines.
  • Said valve block is placed in the harvester head and is coupled, on one hand, to the line for supplying the medium and to the return line of the medium, and on the other hand, to the motor at the end of the harvester head.
  • the motor is particularly the motor of a chain saw for sawing tree trunks, placed in the harvester head.
  • FIG. 2 shows, as an embodiment, a motor M for the fan 11 of a condensing apparatus in a forest machine, the pressurized medium circuit 1 of Fig. 1 being applied in its control.
  • the motor M is coupled to connections MT and MP. Consequently, the pressurized medium circuit is used for the control of the fan motor M.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

A pressurized medium circuit for controlling a motor irrespective of the load, comprising: a pressure line (P, MP), a tank line (T, MT), and a valve (3) whose internal flow resistance can be changed in a controlled manner and which is placed in the pressure line (P, MP), wherein the valve (3) is arranged to control the volume flow of the medium to be supplied to the motor (M). The pressurized medium circuit (1) also comprises a pressure compensator (4) which is placed in a return line (T, MT) and which is arranged to equalize the pressure difference effective over the valve (3) in such a way that the internal flow resistance of the pressure compensator (4) is increased when the pressure difference effective over the valve (3) tends to increase, and that the internal flow resistance of the pressure compensator (4) decreases when the pressure difference effective over the valve (3) tends to decrease.

Description

A COMPENSATING COUPLING IN THE CONTROL OF A MOTOR
The invention relates to a pressurized medium circuit according to claim 1 for controlling a motor irrespective of the loading. The invention relates to a method according to claim 6 in a pressurized medium circuit, for controlling a motor irrespective of the loading. The invention relates to the use of a pressurized medium circuit according to claim 10 for controlling the motor of a fan in a forest machine, irrespective of the loading.
In the control of actuators driven by a pressurized medium, for example motors and cylinders, the control of the volume flow and the pressure is utilized for achieving a desired speed, direction of motion, power, or torque of the actuators. Control valves, such as proportionally controlled directional valves, are used for supplying a desired volume flow to an actuator operating against a positive load in the normal situation but, depending on the structure or other construction of the mechanisms to be controlled, often also against a negative load (so-called escaping load).
The control valves operate on various principles; for example, they have a valve spool that opens and closes valve ports and affects the internal flow resistance of the valve that causes a pressure loss in the medium passing through the valve. The pressurized medium is choked when it flows over the edge of the valve spool, and simultaneously pressure losses are caused, forming a pressure difference e.g. between the input and output ports, that is, the pressure difference of the valve. If the valve spool does not move, the quantity of the volume flow will depend on the pressure difference effective over the control valve. This pressure difference is effected by the feeding pressure of the medium, generated in a pump of the system or maintained in the feeding line, and the loading of the actuator, whose effect is reflected in the pressure line to the actuator.
So that the precise control of the volume flow and thereby, for example, the speed of the actuator would be possible, the above-mentioned pressure difference must be kept constant or the effect of the load must be
9521 WO Appl.doc compensated for in another way. If not, the volume flow will decrease and increase when the pressure caused by the load increases or decreases, respectively. Thus, the effect of the load must be compensated for, particularly in the control valve which operates on the principle of a resistance valve. Generally, a pressure compensator is used to equalize a pressure loss effective over a proportional valve.
EP 0 008 523 presents a method applying the compensation of the return line (meter-out), wherein the pressure difference of the directional valve in the return line is monitored by a compensator in the return line. The compensator chokes the return flow, if a pressure increase occurs in the line from the actuator. Also, document EP 1 355 065 A1 discloses a compensation arranged in the return line to monitor the pressure difference developing in the directional valve during the operation. Said directional valve is in the return line and is effective on the volume flow from the actuator.
Further, EP 0 809 737 B1 teaches the implementation of a so-called meter- out compensation by controlling the choke of the return line in the situation of an escaping load. The choke is used in the inlet line of the actuator to maintain a desired pressure level for the actuator.
For example when the motor is stopped, a strong cavitation occurs in the pressure line, because the motor tends to continue its motion but the supply of the volume flow is cut off. The cavitation has a clear impact on the service life of the components, wherein it is to be avoided.
The aim of the pressurized medium circuit according to the invention is to control the operation of the motor used as an actuator and particularly to slow down and stop it by reducing the risk of cavitation.
A particular application is apparatuses for cutting and delimbing of tree trunks, known as such, for example harvester heads in forest machines. A chain saw is applied in these apparatuses. In particular, the forest machines include harvesters. A particular application is also the condensing apparatuses of forest machines, in which the present pressurized medium circuit is applied for controlling the fan motor. The mass of the fan blades coupled to the motor tends to maintain the motion also in a stopping
9521 WO Appl.doc situation, so the presented circuit is used to prevent cavitation. Conventionally, the fan blades are coupled by means of, for example, a belt to the power transmission shaft of the forest machine, but by using the present circuit, it is possible to control the fan motor irrespective of the speed of rotation of the power transmission shaft. The forest machines include particularly harvesters for processing tree trunks and machines for transporting the tree trunks, or combinations of these.
The pressurized medium circuit according to the invention is characterized by the features presented in claim 1. The method according to the invention is characterized by the features presented in claim 6. The use according to the invention is characterized by the features presented in claim 10. Other embodiments of the invention will be disclosed in the other claims.
The invention will be described in more detail by means of the following example and with reference to the appended drawings, in which
Fig. 1 shows a first embodiment of the invention and the principle of operation of the pressurized medium circuit with its components and couplings, and
Fig. 2 shows a second embodiment of invention.
As shown in Fig. 1 , a pressurized medium circuit 1 comprises a pressure or inlet line P for the incoming pressurized medium, to be coupled to the pressure line of, for example, a forest machine or a harvester head. The pressurized medium is particularly a hydraulic fluid. The return line T is coupled to the return or tank line of the forest machine or harvester head, to which the medium is returned after it has passed through the actuator M, which is a motor known as such. The motor is the saw motor of a harvester head or the like that rotates a chain saw 10 for cutting a tree trunk, in a way known as such. The motor M is coupled between the connection MT of the return line T and the connection MP of the pressure line P. The volume flow determines the speed of rotation of the motor M, and the pressure difference between the connection MT and the connection MP determines the torque of the motor M.
9521 WO Appl.doc - A -
A control valve 3 is coupled in series with the motor M in the pressure line P. In this case, it is a proportionally operating choke implemented by a pilot- controlled or direct-controlled, normally closed 2/2 directional valve. The valve has a closed position and an open position. The valve 3 comprises a control line 2 (connection X) effective on the position of the valve stem (or spool) and equipped with a choke 8, and the pressure of the medium in the control line 2 determines the position of the stem and thereby also the internal flow resistance of the valve 3. The pressure difference effective over the valve 3, in turn, determines the volume flow and the speed of the motor M. Consequently, the control pressure of the control line 2 is used to determine the internal flow resistance of the valve 3 and further the desired volume flow. The control pressure opens the valve 3 and acts against a spring. The motor M is coupled to the connection MP located after the valve 3 in the pressure line P, and to the connection MT located before a valve 4 in a tank line T. The references MP and MT also refer to the line between said connection and the respective valve.
Instead of the pressure control of the control line 2, it is also possible to use electrical control, wherein the position of the stem of the valve 3 is affected by a proportionally operating electric magnet, by using pilot control, if necessary. The volume flow is determined by the control signal that controls the magnet. The control signal is obtained from the control system of the forest machine.
A control valve 4 is coupled in series with the motor M in the return line T, and in this case, it is a proportionally operating choke implemented by a normally open 2/2 valve. The valve has an open position and a position in which the medium is choked, wherein a suitable counterpressure is produced in the return line MT, if necessary, when the pressure in the return line T is low.
Instead of the directional valve 4 equipped with a spool, it is also possible to use other types of valves, in which the medium is passed through various control edges or control openings and in which it is possible to have an effect
9521 WO Appl.doc on the pressure difference caused by the valve. However, the operation corresponds to what will be presented in the following.
The valve 4 (meter-out, valve after the actuator) operates as a pressure compensator for the valve 3 (meter-in, valve before the actuator), for maintaining a constant pressure difference over the valve 3. By placing the pressure compensator 4 in the return line T and the valve 3 in the pressure line P, it is possible to control both the positive load and the negative load (i.e. overspeeding motor) of the motor M. By placing the pressure compensator 4 in the way shown in the figure, it is possible to stop the motor M by avoiding cavitation in the pressure line MP, because the pressure compensator 4, when closed, causes a counterpressure for the motor M as the valve 3 is closed, the pressure in the line MP drops and the pressure of the inlet line is effective in the line P. Pressurized medium of the motor M being stopped is led from the return line MP back to the suction side, to the pressure line MP, via a non-return valve 6, which is closed by the pressure of the pressure line MP during normal operation.
The valve 4 comprises a first control line 5 (equipped with a choke 9) and a second control line 7, which are effective on the position of the valve stem, and the pressure difference between the control lines determines the position of the stem and the internal flow resistance of the valve 4. The internal flow resistance of the valve 4 and the volume flow from the motor M, in turn, determine the pressure difference effective over the valve 4 and simultaneously the level of the counterpressure effective on the operation of the motor M in the line MT (the pressure in the return line T being low). Thus, the difference between the control pressures of the control lines 5 and 7 is effective on the pressure level in the line MT. The pressure of the first control line 5 closes the valve 4 and acts against a spring. The second control line 7 has a reverse effect on the stem and tends to open the valve 4. The counterpressure caused by the valve 4 in the line MT also affects the pressure level in the line MP and particularly the pressure difference over the valve 3, which is to be kept constant.
As the loading of the motor M increases, the pressure in the line MP tends to increase, wherein the elevated pressure in the second control line 7 tends to
9521 WO Appl.doc reduce the internal flow resistance of the valve 4 (i.e. the pressure difference) which, in turn, reduces the pressure in the line MT. As a result, the pressure also decreases in the line MP and the pressure difference over the valve 3 is returned (i.e. increased) to its former level. In a corresponding way, as the loading of the motor M decreases, the pressure in the line MP tends to decrease, wherein the decreased pressure in the second control line 7 allows an increase in the pressure difference (i.e. an internal flow resistance) in the valve 4 by means of the control line 5, which, in turn, increases the pressure in the line MT. As a result, the pressure also increases in the line MP, and the pressure difference over the valve 3 is returned (i.e. decreased) to its former level. Consequently, the pressure difference in the valve 4 is decreased/increased in a way inversely proportional to the loading of the motor M, which, in turn, has an effect on the pressure in the line MP. As a result, the pressure difference effective over the valve 4 decreases/increases in a way directly proportional to the change in the pressure difference in the valve 3.
What is essential is that the pressure compensator 4 is coupled to the return line T, downstream (meter-out) with respect to the motor M used as the actuator, and the valve 3 is coupled in the pressure line P, upstream (meter- in) with respect to the motor M used as the actuator, wherein the actuator is placed between the valves 3 and 4. The valve 3 is not used for choking the medium in the return line T. It is also essential that the pressure compensator 4 is used for controlling the pressure difference effective over the valve 3. The prevailing pressures are monitored by means of the control lines 5 and 7 which, in turn, control the flow resistance of the pressure compensator 4 and the pressure difference developed in the pressure compensator 4.
The pressurized medium circuit of Fig. 1 is preferably integrated in the rest of the pressurized medium circuit of the harvester head, implemented, for example, as a valve block provided with the necessary components and control lines. Said valve block is placed in the harvester head and is coupled, on one hand, to the line for supplying the medium and to the return line of the medium, and on the other hand, to the motor at the end of the harvester head. The motor is particularly the motor of a chain saw for sawing tree trunks, placed in the harvester head. The more detailed selection and
9521 WO Appl.doc dimensioning of the valves 3 and 4 will be obvious for a person skilled in the art on the basis of the operation as presented above. The selection and the dimensioning will be carried out, among other things, on the basis of the selected volume flows and pressure levels and the changes allowed in them.
Figure 2 shows, as an embodiment, a motor M for the fan 11 of a condensing apparatus in a forest machine, the pressurized medium circuit 1 of Fig. 1 being applied in its control. The motor M is coupled to connections MT and MP. Consequently, the pressurized medium circuit is used for the control of the fan motor M.
The invention is not limited solely to the example presented above, but it may vary within the scope of the appended claims.
9521 WO Appl.doc

Claims

Claims
1. A pressurized medium circuit for controlling a motor irrespective of the load, comprising:
a pressure line (P, MP) for supplying a pressurized medium to the motor (M), - a tank line (T, MT) where the medium is returned from the motor
(M), and a valve (3) whose internal flow resistance can be changed in a controlled manner and which is placed in the pressure line (P,
MP), wherein the valve (3) is arranged to control the volume flow of the medium to be supplied to the motor (M), the volume flow being dependent on the pressure difference effective over said valve (3),
characterized in that the pressurized medium circuit (1 ) also com- prises:
a pressure compensator (4) whose internal flow resistance can be changed in a controlled manner and which is placed in the return line (T, MT), wherein the pressure difference effective over the pressure compensator (4) is dependent on the volume flow of the medium led through said pressure compensator (4), and wherein the pressure compensator (4) is arranged to equalize the pressure difference effective over the valve (3) in such a way that the internal flow resistance of the pressure compensator (4) increases when the pressure difference effective over the valve
(3) tends to increase, and that the internal flow resistance of the pressure compensator (4) decreases when the pressure difference effective over the valve (3) tends to decrease.
2. The pressurized medium circuit according to claim 1 , characterized in that the pressurized medium circuit (1 ) also comprises a first control line
9521 WO Appl.doc (5) that is coupled from said pressure compensator (4) to the pressure line (P), upstream with respect to the valve (3), and a second control line (7) that is coupled to the pressure line (MP), downstream with respect to the valve (3), and the pressure difference between the control lines determines the internal flow resistance of the pressure compensator (4).
3. The pressurized medium circuit according to claim 1 or 2, characterized in that said motor (M) is the motor of a fan (11 ) in a forest machine.
4. The pressurized medium circuit according to claim 1 or 2, characterized in that said motor (M) is the motor of a chain saw (10) in a delimbing and cutting apparatus.
5. The pressurized medium circuit according to any of the claims 1 to 4, characterized in that it also comprises a non-return valve (6) coupled between the pressure line (MP) and the return line (MT) and placed in parallel with the motor (M).
6. A method in a pressurized medium circuit for controlling a motor irrespective of the load, comprising at least the following steps:
supplying a pressurized medium via a pressure line (P, MP) to the motor (M), returning the medium from the motor (M) to a tank line (T, MT), and controlling the volume flow of the medium to be supplied to the motor (M) by means of a valve (3), whose internal flow resistance can be changed in a controlled manner and which is placed in the pressure line (P, MP), wherein the volume flow is dependent on the pressure difference effective over said valve
(3),
characterized in
9521 WO Appl.doc equalizing the pressure difference effective over the valve (3) by means of a pressure compensator (4), whose internal flow resistance can be changed in a controlled manner and which is placed in the return line (T, MT), wherein the pressure difference effective over the pressure compensator (4) is dependent on the volume flow of the medium led through said pressure compensator (4), and increasing the internal flow resistance of the pressure compensator (4) when the pressure difference effective over the valve (3) tends to increase, and decreasing the internal flow resistance of the pressure compensator (4) when the pressure difference effective over the valve (3) tends to decrease.
7. The method according to claim 6, characterized in controlling the internal flow resistance of the pressure compensator (4) by means of a pressure difference between the first control line (5) and a second control line (7), wherein the first control line (5) is coupled to the pressure line (P), upstream with respect to the valve (3), and the second control line (7) is coupled to the pressure line (MP), downstream with respect to the valve (3).
8. The method according to claim 6 or 7, characterized in controlling the motor (M) of a fan (11 ) in a forest machine.
9. The method according to claim 6 or 7, characterized in controlling the motor (M) of a chain saw (10) in a delimbing and cutting apparatus.
10. The use of a pressurized medium circuit for the control of the motor of a fan in a forest machine irrespective of the load, characterized in that the pressurized medium circuit comprises:
a pressure line (P, MP) for supplying a pressurized medium to the motor (M), - a tank line (T, MT) where the medium is returned from the motor
(M), and
9521 WO Appl.doc a valve (3), whose internal flow resistance can be changed in a controlled manner and which is placed in the pressure line (P, MP), wherein the valve (3) is arranged to control the volume flow of the medium to be supplied to the motor (M), the volume flow being dependent on the pressure difference effective over said valve (3), a pressure compensator (4) whose internal flow resistance can be changed in a controlled manner and which is placed in the return line (T, MT), wherein the pressure difference effective over the pressure compensator (4) is dependent on the volume flow of the medium led through said pressure compensator (4), and wherein the pressure compensator (4) is arranged to equalize the pressure difference effective over the valve (3) in such a way that the internal flow resistance of the pressure compensator (4) increases when the pressure difference effective over the valve
(3) tends to increase, and that the internal flow resistance of the pressure compensator (4) decreases when the pressure difference effective over the valve (3) tends to decrease.
9521 WO Appl.doc
PCT/EP2006/060064 2005-02-23 2006-02-17 A compensating coupling in the control of a motor WO2006089863A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
SE0602042A SE529574C2 (en) 2005-02-23 2006-10-02 Compensation clutch when controlling a motor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20055086A FI117571B (en) 2005-02-23 2005-02-23 Compensation clutch when controlling a motor
FI20055086 2005-02-23

Publications (1)

Publication Number Publication Date
WO2006089863A1 true WO2006089863A1 (en) 2006-08-31

Family

ID=34224296

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Application Number Title Priority Date Filing Date
PCT/EP2006/060064 WO2006089863A1 (en) 2005-02-23 2006-02-17 A compensating coupling in the control of a motor

Country Status (3)

Country Link
FI (1) FI117571B (en)
SE (1) SE529574C2 (en)
WO (1) WO2006089863A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104847732A (en) * 2015-03-17 2015-08-19 北京理工大学 Valve-controlled cylinder system for unbalance load

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4275643A (en) * 1978-08-25 1981-06-30 Clayton Dewandre & Co. Ltd. Hydraulic control systems
DE4342309A1 (en) * 1993-12-11 1995-06-14 Linde Ag Open circuit hydrostatic drive system for vehicle
US6230606B1 (en) * 1998-05-15 2001-05-15 Smc Kabushiki Kaisha Speed control apparatus for cylinder
EP1355065A1 (en) * 2002-04-17 2003-10-22 Sauer-Danfoss (Nordeborg) A/S Hydraulic control

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4275643A (en) * 1978-08-25 1981-06-30 Clayton Dewandre & Co. Ltd. Hydraulic control systems
DE4342309A1 (en) * 1993-12-11 1995-06-14 Linde Ag Open circuit hydrostatic drive system for vehicle
US6230606B1 (en) * 1998-05-15 2001-05-15 Smc Kabushiki Kaisha Speed control apparatus for cylinder
EP1355065A1 (en) * 2002-04-17 2003-10-22 Sauer-Danfoss (Nordeborg) A/S Hydraulic control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104847732A (en) * 2015-03-17 2015-08-19 北京理工大学 Valve-controlled cylinder system for unbalance load

Also Published As

Publication number Publication date
SE529574C2 (en) 2007-09-18
FI20055086A (en) 2006-08-24
FI20055086A0 (en) 2005-02-23
SE0602042L (en) 2006-10-02
FI117571B (en) 2006-11-30

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