GB2123527A - Jointly controlled brake valve - Google Patents

Jointly controlled brake valve Download PDF

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Publication number
GB2123527A
GB2123527A GB08314210A GB8314210A GB2123527A GB 2123527 A GB2123527 A GB 2123527A GB 08314210 A GB08314210 A GB 08314210A GB 8314210 A GB8314210 A GB 8314210A GB 2123527 A GB2123527 A GB 2123527A
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GB
United Kingdom
Prior art keywords
throttle
pressure
valve
consumer
piston
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.)
Granted
Application number
GB08314210A
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GB2123527B (en
GB8314210D0 (en
Inventor
Gotz Kamm
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ORSTA HYDRAULIK VEB K
Original Assignee
ORSTA HYDRAULIK VEB K
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Application filed by ORSTA HYDRAULIK VEB K filed Critical ORSTA HYDRAULIK VEB K
Publication of GB8314210D0 publication Critical patent/GB8314210D0/en
Publication of GB2123527A publication Critical patent/GB2123527A/en
Application granted granted Critical
Publication of GB2123527B publication Critical patent/GB2123527B/en
Expired legal-status Critical Current

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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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D57/00—Liquid-resistance brakes; Brakes using the internal friction of fluids or fluid-like media, e.g. powders
    • F16D57/06—Liquid-resistance brakes; Brakes using the internal friction of fluids or fluid-like media, e.g. powders comprising a pump circulating fluid, braking being effected by throttling of the circulation
    • 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"
    • F15B11/0445—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" with counterbalance valves, e.g. to prevent overrunning or for braking
    • 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
    • F15B13/01—Locking-valves or other detent i.e. load-holding devices
    • F15B13/015—Locking-valves or other detent i.e. load-holding devices using an enclosed pilot flow valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant 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
    • F15B2211/455—Control of flow in the feed line, i.e. meter-in control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50545—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using braking valves to maintain a back 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
    • F15B2211/70—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
    • 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
    • F15B2211/75—Control of speed of the output member

Abstract

A jointly controlled brake valve for load-independent regulation of the speed of tension-loaded pressure fluid consumers (4) which can undergo a dual action, in which a piston (12) has two end faces (15, 16) of equal size and during a braking action the face (15) is impinged upon, in the opening direction of an adjustable main throttle (8), by inlet pressure fluid (p0) applied upstream of an inlet-side metering throttle (17), and the other face (16) is impinged upon, in the closing direction of the adjustable main throttle (8) by an intermediate fluid pressure (Pz) prevailing in a pressure chamber (19) bounded by the end face (16), the chamber (19) being permanently in communication with the valve-side connection of a discharge-side metering throttle (25) via a second joint throttle (28) in front of which the intermediate pressure (pz) is produced during braking action, the pressure difference over the second joint throttle (28) being relatively slight compared with the mean pressure difference over the adjustable main throttle (8). A connection between both chambers is provided via 22, 21, which connection is closed when the main throttle 8 is closed. The main valve may be provided by a compound piston, Fig. 2, not shown. <IMAGE>

Description

SPECIFICATION Jointly controlled brake valve The invention relates to a jointly controlled brake valve for load-independent regulation of the speed of tension-loaded pressure fluid consumers which can undergo a dual action, including the following features: a) a single or multiple component piston is guided in the casing of the brake valve, is provided with an adjustable main throttle which is closed in the starting position, and is acted on by a compression spring in the closing direction of the adjustable main throttle:: b) the consumer connection and the discharge connection of the brake valve are interconnected via the cross section of flow of the main throttle, which increases in dependence on the regulating distance; c) the main throttle is connected in parallel with a bypass check valve, which opens towards the pressure stream consumer and which is included in the connecting pipe located downstream of the consumer in the effective direction of the external load; d) an inlet-side metering throttle is arranged in the connecting pipe of the consumer which is not interrupted by the bypass check valve; e) a discharge-side metering throttle is arranged in the branch pipe, leading from the connecting pipe with the bypass check valve, at the side of the bypass check valve away from the consumer, to the adjustable main throttle;; f) the consumer-side connection of the inletside metering throttle communicates with the valve side connection of the discharge-side metering throttle via a joint throttle, which is blocked either on complete blocking or opening or only on complete blocking of the cross section of flow of the adjustable main throttle; g) the individual pressure differences over the inlet-side metering throttle, the discharge-side metering throttle and the joint throttle are relatively small compared to the mean pressure difference over the adjustable main throttle.
The dynamic properties of such jointly controlled brake valves depend inter alia on the degree of apportioning of the signal levels of the two controlled variables processed together in them, "consumer discharge stream" and "consumer inlet pressure", at the spring piston system of the brake valve which acts as a comparator. In a known brake valve of this type a stepped piston acted on by a spring has been used for the comparator. Such a construction requires a precision grade double fit to guide the piston in the casing, so that jamming of the piston is definitely avoided, on account of the resultant risk of accidents, and therefore considerably increases manufacturing costs. A further disadvantage of the stepped piston is that the apportioning degree, which is chosen when the diameters of the two sections of the piston are stipulated, cannot be changed later.
The invention aims to reduce the considerable manufacturing cost of jointly controlled brake valves of this type, and to enable the apportioning degree of the signal levels of the two controlled variables to be adapted to the specific conditions of the particular part of the installation.
The problem underlying the invention is to provide a jointly controlled brake valve of this type, which has a simple construction and with which the mixing degree of the two controlled variables can be altered.
According to the present invention there is provided a jointly controlled brake valve for loadindependent regulation of the speed of tensionloaded pressure fluid consumers which can undergo a dual action in which: a) a single or multiple component piston is guided in the casing of the brake valve, is provided with an adjustable main throttle which is closed in the starting position, and is acted on by a compression spring in the closing direction of the adjustable main throttle; b) the consumer connection and the discharge connection of the brake valve are interconnected via the cross section of flow of the main throttle, which increases in dependance on the regulating distance;; c) the main throttle is connected in parallel with a bypass check valve, which opens towards the pressure stream consumer and which is included in the connecting pipe located downstream of the consumer in the effective direction of the external load; d) an inlet-side metering throttle is arranged in the connecting conduit of the consumer which is not interrupted by the bypass check valve; e) a discharge-side metering throttle is arranged in a branch conduit, leading from the connecting conduit with the bypass check valve, at the side of the bypass check valve away from the consumer, to the adjustable main throttle;; f) the consumer-side connection of the inletside metering throttle communicates with the valve side connection of the discharge-side metering throttle via a joint throttle, which is blocked either on complete blocking or opening or only on complete blocking of the cross section of flow of the adjustable main throttle; g) the individual pressure differences over the inlet-side metering throttle, the discharge-side metering throttle and the joint throttle are relatively small compared to the mean pressure difference over the adjustable main throttle; characterised by the following features: h) a single component piston or the control piston of a multiple component piston has two end faces of equal size, of which during the braking action one end face is impinged on, in the opening direction of the adjustable main throttle, with the inlet pressure (pro) applied upstream of the inlet-side metering throttle, and the other end face is impinged on, in the closing direction of the adjustable main throttle, with the intermediate pressure (pz) prevailing in the pressure chamber, bounded by this other end face, in the casing of the brake valve; i) the pressure chamber is permanently in communication with the valve-side connection of the discharge-side metering throttle via a second joint throttle, in front of which the intermediate pressure (pz) is produced during the braking action;; j) the pressure difference over the second joint throttle is relatively slight compared with the mean pressure difference over the adjustable main throttle.
In a jointly controlled brake valve according to the invention with a multiple component piston, the spring chamber which in known manner is in permanent communication with the consumer connection via a filling throttle, can be connected to the pressure chamber by a preliminary relief valve which is arranged in the brake check piston is known manner.
Two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an axial section through a non-tight closing, jointly controlled brake valve in its operating layout, and Figure 2 is an axial section through a tight closing, jointly controlled brake valve.
The non-tight closing, jointly controlled brake valve shown in Figure 1 is intended to govern the speed of pressure fluid consumers which are loaded in the rotary direction of the power take off, with a rotating power take off movement, the rotary direction of the power take off being reversible. Through appropriate operation of a directional control valve 1, each of the two connecting conduits 2 and 3 of the pressure fluid consumer 4 may be put into communication with the pump pressure conduit 5 and/or the discharge conduit 6. A bypass check valve 7 is included in the connecting conduit 3 located downstream of the consumer 4 in the direction in which the external load acts. The valve 7 opens towards the consumer4 and is connected in parallel with an adjustable main throttle 8.The cross section of flow of the main throttle 8 increases dependent on the regulating distance and interconnects a consumer connection 9 and a discharge connection 10 of the brake valve. The bypass check valve 7 may be incorporated in the casing 11 of the brake valve as an integral part of it or connected by a flange onto it. A piston 12 is guided in the casing 11 of the brake valve. It is provided with the throttling element of the adjustable main throttle 8, which is closed in the starting position, and is acted on by a compression spring 14 in the closing direction of the adjustable main throttle 8. The aforementioned throttling element is in the form of axial throttling notches 13. The piston 12 has two end faces 15 and 16 of equal size.One of these end faces 1 5 communicates with a metering throttle 1 7 at the inlet side via a branch conduit 18, which discharges into the connecting conduit 2 at the side of the inlet-metering throttle 1 7 away from the consumer 4. The metering throttle 17 is arranged in the connecting conduit 2 of the consumer 4 which is not interrupted by the bypass check valve 7.The pressure chamber 19 in the casing 11 of the brake valve, bounded by the other end face 1 6 of the piston 1 2, can communicate with the consumer-side connection of the inlet side metering throttle 1 7, via a central bore 20 and radial bores 21 in the piston 12, radial bores 22 in the casing 11 of the brake valve and a joint throttle 24 are arranged in a connecting conduit 23; the throttle 23 is shut off when the cross section of flow of the adjustable main throttle 8 is completely blocked. The pressure chamber 19, containing the compression spring 14, is in permanent communication with the valve-side connection of a discharge-side metering throttle 25, via a second joint throttle 28 arranged in a connecting conduit 27.The metering throttle 25 is arranged in a branch conduit 26 leading to the adjustable main throttle 8 from the connecting conduit 3 with the bypass check valve 7, at the side of the vale 7 away from the consumer 4. The various pressure differences over the metering throttle 1 7 at the inlet side, the joint throttle 24, the metering throttle 25 at the discharge side and the second joint throttle 28 are relatively small compared with the mean difference in pressure over the adjustable main throttle 8.
In the central position 0 of the directional control valve 1 shown in Figure 1 , the pump pressure conduit 5 communicates with the discharge conduit 6, and the fluid stream of the pump flows away through the valve 1 without any pressure. In this case the compression spring 14 presses the piston 1 2 into the starting position illustrated. A raised load is then kept in its current position by an automatic immobilising brake (not shown).
When the directional control valve 1 is switched over to the "load lowering" operation in control position 1, the pump pressure conduit 5 communicates with the connecting conduit 2 and the discharge conduit 6 communicates with the connecting conduit 3. The inlet stream flows through the connecting conduit 2, containing the inlet side metering throttle 17, to the consumer 4.
Since direct discharge from the consumer 4 into the discharge conduit 6 is prevented by the closed bypass check valve 7 in the connecting conduit 3 and by the closed adjustable main throttle 8, the inlet pressure p0 builds up upstream of the inletside metering throttle 1 7 in the connecting conduit 2. Since the end face 1 5 of the piston 12 is impinged on, via the branch conduit 1 8 and possibly a damping throttle 30 arranged therein, with the inlet pressure p,-applied upstream of the inlet-side metering throttle 1 7 - in the opening direction of the adjustable main throttle 8, the piston 1 2 is moved in the direction opposite to the effective direction of the biasing force of the spring 14. As soon as the consumer discharge stream can pass through the branch conduit 29 of the consumer connection 9, out of the cross section of flow of the axial throttling notches 13 of the adjustable main throttle 8 (the cross section increasing dependent on regulating distance), a discharge pressure p, arises in the branch conduit 26 upstream of the discharge-side metering throttle 25.Simultaneously with or shortly after the opening of the cross section of flow of the throttle 8, a bypass connection between the discharge connection 10 and the consumer-side connection of the inlet-side metering throttle 1 7 in the connecting conduit 2 is established, via the connecting conduit 27 with the second joint throttle 28, the pressure chamber 19, the central bore 20, the radial bores 21 and 22 and the connecting conduit 23 with the joint throttle 24; greater differences between the discharge pressure p, and the consumer inlet pressure p1 are therefore compensated for virtually without any delay.The intermediate pressure pz prevailing in the pressure chamber 19, which arises during the braking operation in the connecting conduit 27 upstream of the second joint throttle 28 and which acts on the end face 1 6 of the piston 12 in the closing direction of the throttle 8, takes on a value between the consumer inlet pressure p1 and the discharge pressure p, and is determined by the flow resistances of the two joint throttles 24 and 28. The jointly controlled brake valve carries out two interconnected regulating functions during the braking process, whereby the adjustable main throttle 8 is set dependent both on pressure and flow.The controlled variable "consumer discharge flow" is compared with the command variable "inlet flow", the flow dependent pressure drops at the piston 12, arising at the discharge-side metering throttle 25 and the inlet-side metering throttle 27, producing adjusting forces in opposite directions. Similarly but acting in the opposite direction, a comparison is made between the force exerted on the piston 12 by the consumer inlet pressure p1, which forms a component of the inlet pressure p0 and acts as a second controlled variable, and the reaction force of the compression spring 14 which appears as a command variable. The regulating system is further stabilised by the two series connected joint throttles 24 and 28.Purely statically they always bring the consumer inlet pressure p1 to a value of the same order as the discharge pressure p,, in that fairly large differences between the two pressures are compensated for by a corresponding bypass stream. This prevents both low pressure formation and an excessive rise in the consumer inlet pressure p1 in the connecting conduit between the throttle 1 7 and the consumer 4.
Dynamically speaking the stabilising action of the joint throttles 24 and 28 arises from the fact that the time differences between the discharge pressure p, and the consumer inlet pressure p1, which are always out of phase with one another, lead to interference. By changing the cross sections of flow of the two joint throttles 24 and 28, the degree of apportioning of the signal level of the two controlled variables may be adapted to the specific conditions of the particular part of the installation. A stop 31, provided on the piston 12 and also serving to guide the compression spring 14, limits the regulating distance of the piston 12 and thus determines the maximum possible opening of cross section of flow of the adjustable main throttle 8.
When the directional control valve 1 is in the "load raising"mode in control position 2, the pump pressure conduit 5 communicates with the connecting conduit 3 and the discharge conduit 6 communicates with the connecting conduit 2.
Then the end face 1 5 of the pistori 12 is firstly relieved of pressure, and secondly the inlet pressure, which is propagated through the discharge-side metering throttle 25 and the second joint throttle 28 into the pressure chamber 1 9, acts on the end face 16 of the piston 12, so that the piston 1 2 is pressed into the starting position shown, by this action and by that of the biasing force of the compression spring 1 4. In this position of the piston 12 the bypass connection between the connecting conduits 3 and 2 via the joint throttles 28 and 24 is interrupted. The pressure stream can therefore flow only through the connecting conduit 3 and the opening bypass check valve 7 to the consumer 4, from where it is discharged through the connecting conduit 2 into the discharge conduit 6.The pressure which arises in the process upstream of the metering throttle 1 7 guarantees the necessary discharge pressure of the consumer 4 while the load is being raised.
The tight closing, jointly controlled the brake valve shown in Figure 2 is intended to govern the speed of dual action hydrostatic working cylinders which are loaded in traction. It is particularly appropriate for construction machines which have to work impinged on with operating pressure in the effective direction of the load. In contrast with the non-tight closing, jointly controlled brake valve in Figure 1, a multiple component piston 12 is guided in the casing 11 of the brake valve. It comprises a control piston 32 with the two end faces 1 5 and 1 6 of equal size, a brake check valve 33, provided with the axial throttling notches 13 of the adjustable main throttle 8 and also with two end faces of equal size, and a preliminary relief valve 34 incorporated in the brake check piston 33 and serving to relieve it of pressure.The method of relieving pressure is for the preliminary relief valve 34 to be released by means of a striker peg 35 mounted on the control piston 32, thereby establishing a connection between the spring chamber 37 and the pressure chamber 19. The spring chamber 37 is in permanent communication with the consumer connection 9 via a filling throttle 36 and contains the compression spring 14 which impinges on the brake check piston 33. A conical sealing surface 38 is provided on the brake check piston 33, and its interaction with a sealing edge 39 in the casing 11 of the brake valve shuts off the adjustable main throttle 8 without any leakage in the starting position. As compared with the non-tight closing, jointly controlled brake valve shown in Figure 1, the pressure chamber 1 9 can be connected to the consumer side of the inlet-side metering throttle 17 in the connecting conduit 2, via axial bores 40 and an annular passage 41 in the control piston 32 and the joint throttle 24, arranged in the connecting passage 42 in the casing 11 of the brake valve; the throttle 24 is blocked when the cross section of flow of the adjustable main throttle 8 is fully blocked or open.The pressure chamber 19 is in permanent communication with the valve side of the discharge side metering throttle 25 via the second joint throttle 28, the throttle 25 being arranged in a connecting passage 44; the passage 44 leads from an annular passage 43 in the casing 11 of the brake valve, located at the low pressure side of the adjustable main throttle 8, to the connecting conduit 3.
In the central position 0 of the directional control valve 1 shown in Figure 2, where the pump pressure conduit 5 is connected to the discharge conduit 6, the conveying stream of the pump flows off through the valve 1 without any pressure. The load pressure p2 applied to the consumer connection 9 is propagated through the filling throttle 36 and the central bore 45 into the spring chamber 37. The action of the load pressure p2 and biasing force of the compression spring 14 and the spring chamber 37 cause the conical sealing surface 38 of the brake check piston 33 to be pressed against the sealing edge 39 in the casing 11 of the brake valve.Since the load pressure p2 also acts on the locking elements of the preliminary relief valve 34 and bypass check valve 7, these valves are closed and the load is kept in its current position without any leakage.
When the directional control valve 1 is switched over to the "load lowering" mode in control position 1 , with the pump pressure conduit 5 being linked with the connecting conduit 2 and the discharge conduit 6 with the connecting conduit 3, the inlet stream flows through the connecting conduit 2 with the inlet-side metering throttle 1 7 to the pressure stream consumer 4.
Since the bypass check valve 7 in the connecting conduit 3, the adjustable main throttle 8 and the preliminary relief valve 34 are closed and block the consumer discharge stream, the inlet pressure p0 builds up upstream of the inlet side metering throttle 1 7 in the connecting conduit 2. The pressure p0 acts on the end face 1 5 of the control piston 32, via a branch passage 46 in the housing 11 of the brake valve, an annular passage 47 and radial holes 48 in the control piston 32 and possibly a dampening throttle 30 which may be arranged therein, and moves the control piston 32 towards the brake check piston 33.Since the ratio of the end face 1 5 of the control piston 32 to the ball seating surface of the preliminary relief valve 34, subjected to the load pressure p2, is approximately 30:1 only a slight inlet pressure p0 is necessary to lift the ball of the valve 34 off its seat by means of the striker peg 35, against the action of the compressive force resulting from the load pressure p2 and the biasing force of the valve spring. Because the open valve 34 has considerably less flow resistance than the filling throttle 36, the brake check piston 33 is thereupon relieved of its load, and the pressure in the spring chamber 37 drops to the discharge pressure p, which appears in the connecting passage 44 upstream of the throttle 25.When the preliminary relief valve 34 has been released, the control piston 32 lies against the brake check piston 33 and forms a synchronously moving unit with it. After the further rise in the inlet pressure p0 the biasing force of the compression spring 14, acting in the closing direction of the throttle, is overcome, and the consumer discharge stream can pass via the consumer connection 9, the axial throttling notches 1 3 in the piston 33, the annular passage 43, the connecting passage 44 with the throttle 25 and the discharge connection 10, into the connecting conduit 3 and from there into the discharge conduit 6.Simultaneously with or shortly after the opening of the cross section of flow of the throttle 8, a bypass connection is established between the valve side of the throttle 25 and the consumer side of the throttle 17, via the connecting passage 49, the second joint throttle 28, the pressure chamber 19, the axial bores 40, the annular passage 41 and the connecting passage 42 with the joint throttle 24; quite large distances between the discharge pressure p, and the consumer inlet pressure p1 can therefore be compensated for virtually without any delay.The intermediate pressure pz prevailing in the pressure chamber 19, which is built up in the braking operation upstream of the second joint throttle 28, is propagated through the open valve 34 and the central bore 45 into the spring chamber 37 and thus impinges on the two end surfaces of the piston 33, which are of the same size. Since the resultant compressive forces acting on the piston 33 therefore cancel each other out, and the intermediate pressure pz additionally acts on the end face 1 6 of the control piston 32 in the closing direction of the throttle 8, together with the repelling power of the compression spring 14, the regulating principles for the non-tight closing, jointly controlled brake valve in Figure 1 and for the tight closing, jointly controlled brake valve in Figure 2 are exactly the same.
If the annular piston surface of the hydrostatic working cylinder used as the pressure stream consumer 4-for example in the case of multipurpose dredgers with a dipper ladle during the trenching process - is subjected to the operating pressure in the effective direction of the external traction load, then the inlet pressure p0 generated by the pump causes the control piston 32 and brake check piston 33 to shift far enough to bring the stop 31 into contact with the casing 11 of the brake valve, and completely to open the cross section of flow of the adjustable main throttle 8.
Since the bypass connection between the connecting conduits 3 and 2 via the joint throttles 28 and 24 is then interrupted, and the entire inlet stream flows through the connecting conduit 2 to the consumer 4, all the available hydrostatic driving power can therefore be supplied to the consumer.
When the directional control valve 1 is switched back to its central position 0, the inlet pressure p0 collapses and there is no longer any opening force acting on the multiple component piston 12. The force of the valve spring of the valve 34, which must be strong to shift the control piston 32, closes the valve 34 in the brake check piston 33. The load pressure p2 builds up in the spring chamber 37 by way of the consumer connection 9, the filling throttle 36 and the central bore 45. In conjunction with the force of the compression spring 14, the pressure p2 moves the brake check piston 33 and control piston 32 into the closed position of the main valve 8 and finally presses the conical sealing surface 38 on the piston 33 against the sealing edge 39 in the casing 11 of the brake valve.Now the load is again held in its current position without any leakage.
When the valve 1 is in "load raising" mode in control position 2, with the pump pressure conduit 5 communicating with the connecting conduit 3 and the discharge conduit 6 with the connecting conduit 2, and with the end face 1 5 of the control piston 32 relieved of pressure, the inlet pressure which is propagated through the metering throttle 25 and the second joint throttle 28 into the pressure chamber 19, acts on the end face 1 6 of the control piston 32 and presses it into the starting position shown. In this position of the multiple component piston 12, the bypass connection between the connecting conduits 3 and 2 via the joint throttles 28 and 24 is again interrupted, and it is only via the connecting conduit 3, the opening bypass check valve 7 and the consumer connection 9 that the pressure stream can reach the consumer 4, where it causes the load to be raised. Since the inlet pressure builds up in the process in the spring chamber 37, via the filling throttle 36 and the central bore 45, the adjustable main throttle 8 remains closed.

Claims (3)

1. A jointly controlled brake valve for loadindependent regulation of the speed of tensionloaded pressure fluid consumers which can undergo a dual action in which: a) a single or multiple component piston is guided in the casing of the brake valve, is provided with an adjustable main throttle which is closed in the starting position, and is acted on by a compression spring in the closing direction of the adjustable main throttle; b) the consumer connection and the discharge connection of the brake valve are interconnected via the cross section of flow of the main throttle, which increases in dependence on the regulating distance;; c) the main throttle is connected in parallel with a bypass check valve, which opens towards the pressure stream consumer and which is included in the connecting pipe located downstream of the consumer in the effective direction of the external load; d) an inlet-side metering throttle is arranged in the connecting conduit of the consumer which is not interrupted by the bypass check valve; e) a discharge-side metering throttle is arranged in a branch conduit, leading from the connecting conduit with the bypass check valve, at the side of the bypass check valve away from the consumer, to the adjustable main throttle;; f) the consumer-side connection of the inletside metering throttle communicates with the valve side connection of the discharge-side metering throttle via a joint throttle, which is blocked either on complete blocking or opening or only on complete blocking of the cross section of flow of the adjustable main throttle; g) the individual pressure differences over the inlet-side metering throttle, the discharge-side metering throttle and the joint throttle are relatively small compared to the mean pressure difference over the adjustable main throttle; characterised by the following features; h) a single component piston or the control piston of a multiple component piston has two end faces of equal size, of which during the braking action one end face is impinged on, in the opening direction of the adjustable main throttle, with the inlet pressure (pO applied upstream of the inlet-side metering throttle, and the other end face is impinged on, in the closing direction of the adjustable main throttle, with the intermediate pressure (pz) prevailing in the pressure chamber, bounded by this other end face, in the casing of the brake valve;; i) the pressure chamber is permanently in communication with the valve-side connection of the discharge-side metering throttle via a second joint throttle, in front of which the intermediate pressure (pz) is produced during the braking action; j) the pressure difference over the second joint throttle is relatively slight compared with the mean pressure difference over the adjustable main throttle.
2. A jointly controlled brake valve as claimed in claim 1 provided with a multiple component piston, in which the spring chamber which is in permanent communication with the consumer connection via a filling throttle, can be connected to the pressure chamber by a preliminary relief valve which is arranged in the brake check piston.
3. A jointly controlled brake valve for loadindependent regulation of the speed of tensionloaded pressure fluid consumers which can undergo a dual action, substantially as hereinbefore described with reference to and as iliustrated in figure 1 or figure 2 of the accompanying drawings.
GB08314210A 1982-07-13 1983-05-23 Jointly controlled brake valve Expired GB2123527B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DD24160782A DD205727A1 (en) 1982-07-13 1982-07-13 COMPRESSED BRAKE VALVE

Publications (3)

Publication Number Publication Date
GB8314210D0 GB8314210D0 (en) 1983-06-29
GB2123527A true GB2123527A (en) 1984-02-01
GB2123527B GB2123527B (en) 1985-11-06

Family

ID=5539951

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08314210A Expired GB2123527B (en) 1982-07-13 1983-05-23 Jointly controlled brake valve

Country Status (2)

Country Link
DD (1) DD205727A1 (en)
GB (1) GB2123527B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4420136A1 (en) * 1994-06-09 1995-12-14 Rexroth Mannesmann Gmbh Hydraulic valve, especially for releasing a spring brake
GB2354057A (en) * 1999-09-10 2001-03-14 Barrus E P Ltd A valve and a marine propulsion unit incorporating a valve
EP1619396A2 (en) * 2004-07-23 2006-01-25 Volvo Construction Equipment Holding Sweden AB Variable regeneration valve of heavy equipment

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4420136A1 (en) * 1994-06-09 1995-12-14 Rexroth Mannesmann Gmbh Hydraulic valve, especially for releasing a spring brake
GB2354057A (en) * 1999-09-10 2001-03-14 Barrus E P Ltd A valve and a marine propulsion unit incorporating a valve
EP1619396A2 (en) * 2004-07-23 2006-01-25 Volvo Construction Equipment Holding Sweden AB Variable regeneration valve of heavy equipment
EP1619396A3 (en) * 2004-07-23 2011-11-02 Volvo Construction Equipment Holding Sweden AB Variable regeneration valve of heavy equipment

Also Published As

Publication number Publication date
GB2123527B (en) 1985-11-06
GB8314210D0 (en) 1983-06-29
DD205727A1 (en) 1984-01-04

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