WO1997006045A1 - Valve arrangement for hydraulic work motors, especially for steering devices - Google Patents

Valve arrangement for hydraulic work motors, especially for steering devices Download PDF

Info

Publication number
WO1997006045A1
WO1997006045A1 PCT/DK1996/000337 DK9600337W WO9706045A1 WO 1997006045 A1 WO1997006045 A1 WO 1997006045A1 DK 9600337 W DK9600337 W DK 9600337W WO 9706045 A1 WO9706045 A1 WO 9706045A1
Authority
WO
WIPO (PCT)
Prior art keywords
valve
valve arrangement
inlet
bore
control pressure
Prior art date
Application number
PCT/DK1996/000337
Other languages
French (fr)
Inventor
Holger Krogsgård ROM
Original Assignee
Danfoss A/S
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 Danfoss A/S filed Critical Danfoss A/S
Priority to AU66547/96A priority Critical patent/AU6654796A/en
Publication of WO1997006045A1 publication Critical patent/WO1997006045A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/061—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle provided with effort, steering lock, or end-of-stroke limiters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D12/00—Steering specially adapted for vehicles operating in tandem or having pivotally connected frames

Definitions

  • the invention relates to a valve arrangement for hydraulic work motors, especially for steering devices, that are operated by a control device, which valve arrangement has an inlet to be connected to a motor line, an outlet to be connected to a tank line and a valve, between the inlet and outlet, that opens in dependence on the input pressure.
  • proximity sensors which are disclosed in the same publication, operate a blocking device that acts on the steering hand wheel.
  • a magnetic valve that connects the pump line to the tank can be opened (DE 25 00 137 Al) .
  • valve is controlled in dependence on the rate of rise of the input pressure and opens when the rate of rise exceeds a predetermined value.
  • the valve that is con ⁇ trolled by the rate of rise of the input pressure limits the acceleration of the movement of the motor. That obviates too rapid changes and excessive acceler ⁇ ation of the steered parts in a steering device and in a vehicle with centre pivot steering especially obvi ⁇ ates the unpleasant sideways accelerations.
  • the valve has a slide member which is arranged between two control pressure cham ⁇ bers, the first of which is connected directly to the inlet and the second of which is connected to the inlet by way of a throttle and further includes a spring. Since the build-up of pressure in the second control pressure chamber is delayed by virtue of the throttle, dependence on the rate of rise of the input pressure is obtained by simple means.
  • the slide member have a first internal bore running from one face and a second internal bore running from the other face, which internal bores are connected to one another by way of the throttle, that the second internal bore accommodate the spring, the first control pressure chamber be adjacent to the inlet, the second control pressure chamber be a substantially closed chamber and the two control pressure chambers be connected by a bore that is occupied by the slide member, through which bore there passes a transverse bore that is connected to the outlet and which bore is unblocked when the valve is actuated.
  • an auxiliary valve be connected between the second control pressure chamber and the outlet, which auxiliary valve opens when the pressure in the second control pressure chamber exceeds a predetermined value.
  • the auxiliary valve responds to excess pressure when the rate of rise of the input pressure is permissible and ensures that the valve opens by itself.
  • the auxiliary valve can be in the form of a spring-loaded check valve, that is to say it can be of very simple construction.
  • a restrictor that is to say a throttle member, be connected upstream of the outlet. That prevents a direct short-circuit to the tank if, for whatever reason, the valve were no longer to close after opening, that is to say, for example, if it became stuck.
  • valves and optionally auxiliary valves be provided in a driving motor that can be driven in both directions, each of the inlets of which valves is to be associated with a motor line and the outlets of which are to be associated with the tank line.
  • Such an arrangement can be housed in a single constructional unit and can therefore be added easily to the rest of the hydraulic circuit.
  • Fig. l is a schematic representation of a steering device showing the position in which the valve arrangement according to the invention is installed
  • Fig. 2 is a circuit diagram of the valve arrangement according to the invention.
  • Fig. 3 shows an exemplary construction for a valve arrangement according to the invention.
  • Fig. 1 shows a control device 1 that can be operated by means of a steering hand wheel 2.
  • a connection P is connected to a pump 3 and a connection T is connected to a tank 4.
  • Connections L and R lead via motor lines 5 and 6, respectively, to a hydraulic work motor 7, the shafts 8 of which are connected to parts to be steered.
  • a valve arrangement 9 has a connection L' which is connected to the motor line 5, a connection R' which is connected to the motor line 6 and a connection T' which is connected to the tank 4.
  • valve arrangement 9 The structure of that valve arrangement 9 is shown in Fig. 2.
  • the valve arrangement has two valves 10 and 11, of which only valve 10 is described in detail since the valve 11 is of the same construction.
  • the valve 10 has a slide member 12. Its first control pressure chamber 13 is connected directly to the inlet 14, that is to the connection L' , the second control pressure chamber 15, in which also a spring 16 acts, is con ⁇ nected to the inlet 14 by way of a throttle 17.
  • that throttle 17 creates delay which is proportional to the size of the control pressure chamber 15 and inversely proportional to the size of the throttle 17. Since there is normally no interest in very small sizes of throttle on account of the risk of blockage, a compromise will be made between a sufficiently large size of throttle (for example, 0.6 mm diameter) and the volume of the control pressure chamber that is appropriate thereto.
  • valve 10 opens when the rate of rise of pressure at the inlet 14 is so great that the force of the spring 16 is overcome as a result of that delay.
  • the volume of oil in the control pressure chamber 15 normally yields sufficiently so that it does not impede the opening action.
  • a certain ability to yield must be provided by a buffer or the like. Too great acceleration of the motor movement is pre ⁇ vented as a result of the pressurized fluid's flowing to the outlet 18, that is to the connection T' .
  • a restrictor 19 is connected upstream of the outlet 18. That prevents a direct short-circuit between a motor line and the tank, were the slide member 12 of the valve 10 to become stuck.
  • auxiliary valve 20 which is arranged in a line 21 between the second pressure chamber 15 and the outlet 18. This is a spring-loaded check valve which responds when the pressure in the second control pressure chamber 15 exceeds a predeter ⁇ mined value. The auxiliary valve 20 then opens a little way, as a result of which the slide member 12 moves into the open position and the excess pressure is reduced.
  • a bore 23 is provided as an extension of the connection 1 , through which bore 23 there passes a transverse bore 24 leading to the connection T'.
  • the section of the bore 23 that is shown on the left in the drawing forms the first control pressure chamber 13.
  • a substantially closed housing chamber forms the second control pressure chamber 15.
  • the slide member 12 has a first internal bore 25 that runs from the first control pressure chamber 13 and a second internal bore 26 that runs from the second control pressure chamber 15.
  • the throttle 17 is located in between. Further ⁇ more, the spring 16 is inserted in the second internal bore 26, which spring, if required, can be adjusted by an adjusting device 27.
  • auxiliary valve 20 is shown schematically but only for the valve 10.
  • valve arrangement 9 can take on further valve functions, for example, inlet valves, as is known per se.

Abstract

A valve arrangement (9) for hydraulic work motors, especially for steering devices, that are operated by a control device, has an inlet (14) to be connected to a motor line, an outlet (18) to be connected to a tank line and a valve (10, 11) between the inlet and the outlet. The valve (10, 11) is controlled in dependence on the rate of rise of the input pressure and opens when the rate of rise exceeds a predetermined value. In that manner, undesirable acceleration of the work motor can be prevented.

Description

Valve arrangement for hydraulic work motors, especially for steering devices
The invention relates to a valve arrangement for hydraulic work motors, especially for steering devices, that are operated by a control device, which valve arrangement has an inlet to be connected to a motor line, an outlet to be connected to a tank line and a valve, between the inlet and outlet, that opens in dependence on the input pressure.
Known valve arrangements of that type (DE 32 46 137 C2) have pressure relief valves that respond when the pressure in the associated motor line exceeds a prede¬ termined threshold value. In that manner, damage can be avoided that otherwise occurs when there is excess pressure.
In order to prevent mechanically hard impact of the parts that are connected to the work motor against the end stops, proximity sensors, which are disclosed in the same publication, operate a blocking device that acts on the steering hand wheel. Alternatively, a magnetic valve that connects the pump line to the tank can be opened (DE 25 00 137 Al) .
In many cases there are, however, already difficulties if the parts that are driven by the work motor experi¬ ence too great acceleration. That is the case espec¬ ially for vehicles with centre pivot steering because the driver of such a vehicle is subjected to very unpleasant sideways acceleration. The problem underlying the invention is therefore to provide a valve arrangement of the type described at the outset, with which a greater degree of user- friendliness is obtained.
That problem is solved according to the invention in that the valve is controlled in dependence on the rate of rise of the input pressure and opens when the rate of rise exceeds a predetermined value.
Since the pressure in the motor line is responsible for the speed of the work motor, the valve that is con¬ trolled by the rate of rise of the input pressure limits the acceleration of the movement of the motor. That obviates too rapid changes and excessive acceler¬ ation of the steered parts in a steering device and in a vehicle with centre pivot steering especially obvi¬ ates the unpleasant sideways accelerations.
In a preferred embodiment, the valve has a slide member which is arranged between two control pressure cham¬ bers, the first of which is connected directly to the inlet and the second of which is connected to the inlet by way of a throttle and further includes a spring. Since the build-up of pressure in the second control pressure chamber is delayed by virtue of the throttle, dependence on the rate of rise of the input pressure is obtained by simple means.
Constructionally, it is recommended that the slide member have a first internal bore running from one face and a second internal bore running from the other face, which internal bores are connected to one another by way of the throttle, that the second internal bore accommodate the spring, the first control pressure chamber be adjacent to the inlet, the second control pressure chamber be a substantially closed chamber and the two control pressure chambers be connected by a bore that is occupied by the slide member, through which bore there passes a transverse bore that is connected to the outlet and which bore is unblocked when the valve is actuated.
It is also advantageous that an auxiliary valve be connected between the second control pressure chamber and the outlet, which auxiliary valve opens when the pressure in the second control pressure chamber exceeds a predetermined value. The auxiliary valve responds to excess pressure when the rate of rise of the input pressure is permissible and ensures that the valve opens by itself. As a result, the per se conventional monitoring of excess pressure is carried out without the use of a normal pressure relief valve but merely by the additional use of a small auxiliary valve.
Especially, the auxiliary valve can be in the form of a spring-loaded check valve, that is to say it can be of very simple construction.
It is also advantageous that a restrictor, that is to say a throttle member, be connected upstream of the outlet. That prevents a direct short-circuit to the tank if, for whatever reason, the valve were no longer to close after opening, that is to say, for example, if it became stuck.
It is also advantageous that two valves and optionally auxiliary valves be provided in a driving motor that can be driven in both directions, each of the inlets of which valves is to be associated with a motor line and the outlets of which are to be associated with the tank line. Such an arrangement can be housed in a single constructional unit and can therefore be added easily to the rest of the hydraulic circuit.
The invention is explained hereinafter in greater detail with reference to embodiments shown in the drawings, in which:
Fig. l is a schematic representation of a steering device showing the position in which the valve arrangement according to the invention is installed,
Fig. 2 is a circuit diagram of the valve arrangement according to the invention, and
Fig. 3 shows an exemplary construction for a valve arrangement according to the invention.
Fig. 1 shows a control device 1 that can be operated by means of a steering hand wheel 2. A connection P is connected to a pump 3 and a connection T is connected to a tank 4. Connections L and R lead via motor lines 5 and 6, respectively, to a hydraulic work motor 7, the shafts 8 of which are connected to parts to be steered. A valve arrangement 9 has a connection L' which is connected to the motor line 5, a connection R' which is connected to the motor line 6 and a connection T' which is connected to the tank 4.
The structure of that valve arrangement 9 is shown in Fig. 2. The valve arrangement has two valves 10 and 11, of which only valve 10 is described in detail since the valve 11 is of the same construction. The valve 10 has a slide member 12. Its first control pressure chamber 13 is connected directly to the inlet 14, that is to the connection L' , the second control pressure chamber 15, in which also a spring 16 acts, is con¬ nected to the inlet 14 by way of a throttle 17. When there is a rise in pressure, that throttle 17 creates delay which is proportional to the size of the control pressure chamber 15 and inversely proportional to the size of the throttle 17. Since there is normally no interest in very small sizes of throttle on account of the risk of blockage, a compromise will be made between a sufficiently large size of throttle (for example, 0.6 mm diameter) and the volume of the control pressure chamber that is appropriate thereto.
Accordingly, the valve 10 opens when the rate of rise of pressure at the inlet 14 is so great that the force of the spring 16 is overcome as a result of that delay. The volume of oil in the control pressure chamber 15 normally yields sufficiently so that it does not impede the opening action. As necessary, a certain ability to yield must be provided by a buffer or the like. Too great acceleration of the motor movement is pre¬ vented as a result of the pressurized fluid's flowing to the outlet 18, that is to the connection T' .
A restrictor 19 is connected upstream of the outlet 18. That prevents a direct short-circuit between a motor line and the tank, were the slide member 12 of the valve 10 to become stuck.
Also provided is an auxiliary valve 20 which is arranged in a line 21 between the second pressure chamber 15 and the outlet 18. This is a spring-loaded check valve which responds when the pressure in the second control pressure chamber 15 exceeds a predeter¬ mined value. The auxiliary valve 20 then opens a little way, as a result of which the slide member 12 moves into the open position and the excess pressure is reduced.
An exemplary construction is shown in Fig. 3. In a housing 22, a bore 23 is provided as an extension of the connection 1 , through which bore 23 there passes a transverse bore 24 leading to the connection T'. The section of the bore 23 that is shown on the left in the drawing forms the first control pressure chamber 13. A substantially closed housing chamber forms the second control pressure chamber 15. The slide member 12 has a first internal bore 25 that runs from the first control pressure chamber 13 and a second internal bore 26 that runs from the second control pressure chamber 15. The throttle 17 is located in between. Further¬ more, the spring 16 is inserted in the second internal bore 26, which spring, if required, can be adjusted by an adjusting device 27.
When the force of the spring 16 is overcome, the slide member 12 moves to the right, as a result of which the bore 24 is connected to the bore 23 and therefore the inlet is connected to the outlet. The auxiliary valve 20 is shown schematically but only for the valve 10.
Of course, the valve arrangement 9 can take on further valve functions, for example, inlet valves, as is known per se.

Claims

Patent Claims
1. Valve arrangement for hydraulic work motors, especially for steering devices, that are operated by a control device, which valve arrangement has an inlet to be connected to a motor line, an outlet to be connected to a tank line and a valve, between the inlet and out¬ let, that opens in dependence on the input pressure, characterized in that the valve (10, 11) is controlled in dependence on the rate of rise of the input pressure and opens when the rate of rise exceeds a predetermined value.
2. Valve arrangement according to claim 1, character¬ ized in that the valve (10) has a slide member (12) which is arranged between two control pressure chambers (13, 15), the first (13) of which is connected directly to the inlet (14) and the second (15) of which is connected to the inlet (14) by way of a throttle (17) and further includes a spring (16) .
3. Valve arrangement according to claim 2, character¬ ized in that the slide member (12) has a first internal bore (25) that runs from one face and a second internal bore (26) that runs from the other face, which internal bores are connected to one another by way of the throttle (17) , the second internal bore (26) accommo¬ dates the spring (16) , the first control pressure chamber (13) is adjacent to the inlet, the second control pressure chamber (15) is a substantially closed chamber, and the two control pressure chambers (13, 15) are connected by a bore (23) that is occupied by the slide member (12), through which bore (23) there passes a transverse bore (24) that is connected to the outlet (18) and which bore (23) is unblocked when the valve (10) is actuated.
4. Valve arrangement according to claim 2 or 3, characterized in that an auxiliary valve (20) is con¬ nected between the second control pressure chamber (15) and the outlet (18) , which auxiliary valve (20) opens when the pressure in the second control pressure cham¬ ber (15) exceeds a predetermined value.
5. Valve arrangement according to claim 4, character¬ ized in that the auxiliary valve (20) is in the form of a spring-loaded check valve.
6. Valve arrangement according to any one of claims 1 to 5, characterized in that a restrictor (19) is con¬ nected upstream of the outlet (18) .
7. Valve arrangement according to any one of claims 1 to 6, characterized in that in a driving motor (7) that can be driven in both directions, two valves (10, 11) and optionally auxiliary valves (20) are provided, each of the inlets of which is to be associated with a motor line (5, 6) , respectively, and the outlets (18) of which are to be associated with the tank line.
PCT/DK1996/000337 1995-08-10 1996-08-08 Valve arrangement for hydraulic work motors, especially for steering devices WO1997006045A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU66547/96A AU6654796A (en) 1995-08-10 1996-08-08 Valve arrangement for hydraulic work motors, especially for steering devices

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19529455.6 1995-08-10
DE1995129455 DE19529455A1 (en) 1995-08-10 1995-08-10 Valve arrangement for hydraulic working motors, especially for steering devices

Publications (1)

Publication Number Publication Date
WO1997006045A1 true WO1997006045A1 (en) 1997-02-20

Family

ID=7769189

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1996/000337 WO1997006045A1 (en) 1995-08-10 1996-08-08 Valve arrangement for hydraulic work motors, especially for steering devices

Country Status (3)

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AU (1) AU6654796A (en)
DE (1) DE19529455A1 (en)
WO (1) WO1997006045A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108275202A (en) * 2017-01-06 2018-07-13 丹佛斯动力系统有限公司 Hydraulic steering

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4019603A (en) * 1975-12-24 1977-04-26 Caterpillar Tractor Co. Understeer vehicle steering system
US4081054A (en) * 1977-04-07 1978-03-28 Caterpillar Tractor Co. Hydraulic steering with feedback
US4345661A (en) * 1978-06-08 1982-08-24 Honda Giken Kogyo Kabushiki Kaisha Anti-roll system for vehicles
DE3246137C2 (en) * 1982-12-14 1985-02-14 Danfoss A/S, Nordborg Hydrostatic steering device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481770A (en) * 1982-03-22 1984-11-13 Caterpillar Tractor Co. Fluid system with flow compensated torque control

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4019603A (en) * 1975-12-24 1977-04-26 Caterpillar Tractor Co. Understeer vehicle steering system
US4081054A (en) * 1977-04-07 1978-03-28 Caterpillar Tractor Co. Hydraulic steering with feedback
US4345661A (en) * 1978-06-08 1982-08-24 Honda Giken Kogyo Kabushiki Kaisha Anti-roll system for vehicles
DE3246137C2 (en) * 1982-12-14 1985-02-14 Danfoss A/S, Nordborg Hydrostatic steering device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108275202A (en) * 2017-01-06 2018-07-13 丹佛斯动力系统有限公司 Hydraulic steering

Also Published As

Publication number Publication date
DE19529455A1 (en) 1997-02-13
AU6654796A (en) 1997-03-05

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