Valve device

Abstract

The invention relates to a hydraulic valve device (1) including a high pressure connection (P) and a low pressure connection (T); at least one motor port connection (A) that is connectable to a motor port (A) on a hydraulic motor (M), preferably a hydraulic cylinder; a flow control valve (F), which is arranged between the high pressure connection (P) and the motor port connection (A) and which includes a flow opening (18) that is adjustable between a fully closed position and a fully open position; and a pressure regulator (R) that is arranged between the high pressure connection (P) and the flow regulating valve (F), wherein a regulator pressure (PR) that acts at a first connection point (3) between the pressure regulator (R) and the flow regulating valve (F) acts on the pressure regulator (R) via a first control conduit (4) to close the same. A second control conduit (5) including a first restrictor (6), is arranged to convey a load pressure (PL) that acts at the motor port connection (A) from a second connection point (7) positioned between the flow regulating valve (F) and the motor port connection (A) via the first restrictor (6) to a third connection point (8) at which a first control pressure (Pc) acts and which third connection point (8) is connected to the pressure regulator (R) to act on the same in the opening direction by means of said first control pressure (Pc), wherein the third connection point (8) is connected to the low pressure connection (T), via an adjustable second restrictor (9).

Claims

1. A hydraulic valve device including: a high pressure connection and a low pressure connection; at least one motor port connection which is connectable to a motor port on a hydraulic motor; a flow regulating valve, which is arranged between the high pressure connection and the motor port connection and which includes a flow opening that is adjustable between a fully closed position and a fully open position; a pressure regulator, which is arranged between the high pressure connection and the flow regulating valve, wherein a regulator pressure acting at a first connection point between the pressure regulator and the flow regulating valve via a first control conduit acts on the pressure regulator in order to close the same, a second control conduit including a first restrictor, which control conduit is arranged to convey a load pressure that acts at the motor port connection from a second connection point positioned between the flow regulating valve and the motor port connection via the first restrictor to a third connection point where a first control pressure acts and which third connection point is in connection with the pressure regulator in order to act on the same in the opening direction with said first control pressure, wherein the third connection point is connected to the low pressure connection, via an adjustable second restrictor, a third control conduit including a constantly open third restrictor which is arranged in order to convey the regulator pressure acting at the first connection point between the pressure regulator and the flow regulating valve via the third restrictor to said third connection point, and the third control conduit, which is in the form of a though hole in a valve spool of the flow regulating valve, connects the first connection point with the third connection point such that there will always be a flow through the third control conduit, independent of the position of the valve spool of the flow regulating valve.

2. Hydraulic valve device according to claim 1, wherein a non-return valve is arranged between the second connection point and the third connection point, which non-return valve opens towards the second connection point in order to convey a flow in parallel with the flow regulating valve when the control pressure at the third connection point is greater than the load pressure at the second connection point.

3. Hydraulic valve device according to claim 1, wherein the adjustable second restrictor is regulated in dependence of the flow regulating valve.

4. Hydraulic valve device according to claim 3, wherein the adjustable second restrictor is regulated such that the flow through the second restrictor decreases when the flow through area of the opening of the flow regulating valve towards the motor port connection is increased.

5. Hydraulic valve device according to claim 1, wherein the adjustable second restrictor is arranged to be electrically regulated.

6. Hydraulic valve device according to claim 1, wherein a spring is arranged to constantly act on the pressure regulator in order to open the same.

7. A hydraulic valve device comprising: a valve housing having a high pressure connection, low pressure connection and a motor port connection connectable to a motor port on a hydraulic motor; a flow regulating valve being arranged in the housing between the high pressure connection and the motor port connection and including a flow opening adjustable between a fully closed position and a fully open position; a pressure regulator arranged in the housing between the high pressure connection and the flow regulating valve such that a regulator pressure acting at a first connection point between the pressure regulator and the flow regulating valve via a first control conduit acts on the pressure regulator to close the pressure regulator; a second control conduit including a first restrictor, the second control conduit being arranged to convey a load pressure acting at the motor port connection from a second connection point positioned between the flow regulating valve and the motor port connection via the first restrictor to a third connection point where a first control pressure acts, the third connection point being connected in fluid communication with the pressure regulator to act on the pressure regulator in the opening direction with the first control pressure, the third connection point being connected in fluid communication with the low pressure connection via an adjustable second restrictor; and a third control conduit including a constantly open third restrictor arranged to convey the regulator pressure acting at the first connection point between the pressure regulator and the flow regulating valve via the third restrictor to the third connection point, the third control conduit being constantly open and being a though hole in a valve spool of the flow regulating valve and connecting the first connection point with the third connection point such that there will always be a flow through the third control conduit, independent of the position of the valve spool of the flow regulating valve.

8. A hydraulic valve device according to claim 7, wherein a non-return valve is arranged between the second connection point and the third connection point, the non-return valve opening towards the second connection point to convey a flow in parallel with the flow regulating valve when the control pressure at the third connection point is greater than the load pressure at the second connection point.

9. A hydraulic valve device according to claim 7, wherein the adjustable second restrictor is regulatable dependent on the flow regulating valve.

10. A hydraulic valve device according to claim 9, wherein the adjustable second restrictor is regulatable such that flow through the second restrictor decreases when a flow through area of an opening of the flow regulating valve towards the motor port connection is increased.

11. A hydraulic valve device according to claim 7, wherein the adjustable second restrictor is electrically regulatable.

12. A hydraulic valve device according to claim 7, wherein a spring is arranged to constantly act on the pressure regulator to open the pressure regulator.

Description

SHORT DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a conventional LS-valve according to the description above;

(2) FIG. 2 shows a conventional LS-valve for pressure control according to the description above;

(3) FIG. 3 shows a diagram of a valve device according to a first variant of the invention;

(4) FIG. 4 shows a section of a specific embodiment of a valve device according to the first variant of the invention;

(5) FIG. 5 shows a diagram of the specific embodiment that is shown in FIG. 4;

(6) FIG. 6 shows a diagram of a valve device according to a second variant of the invention;

(7) FIG. 7 shows a section of a specific embodiment a valve device according to the second variant of the invention;

(8) FIG. 8 shows a diagram of the specific embodiment that is shown in FIG. 7.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENTS

(9) FIG. 3 illustrates a simplified diagram of a first embodiment of a valve device according to the invention. The valve device 1 includes a high pressure connection P, which is connected to a pressure source in form of a pump P, preferably a pump with a variable displacement. Further, the valve device 1 includes a low pressure connection T, which is connected to a low pressure tank T.

(10) At the other end of the valve device 1 a motor port connection A is arranged, which is connectable to a motor port A on a hydraulic motor M, which in the shown embodiment is illustrated by a single acting hydraulic cylinder (see FIG. 4). The invention is however not limited to the use of single acting hydraulic cylinders, but may on the contrary be advantageously used on other types of hydraulic motors such as e.g. double acting hydraulic cylinders, shaft driving motors, or the like.

(11) A flow control valve F, also referred to as a flow regulating valve, is arranged between the high pressure connection P and the motor port connection A, in order to regulate the flow towards the motor port connection A. For this purpose the flow regulating valve F includes a flow opening that is adjustable between a fully closed position and a fully open position. The flow over the flow regulating valve F is proportional to the size of the flow opening but is also dependent of the pressure drop over the flow regulating valve, why the flow is dependent on the pressure both upstream and downstream of the flow regulating valve F. Preferably, a first non-return valve 2 is arranged downstream of the flow regulating valve F in order to prevent flow in the wrong direction, i.e. in the opposite direction to the pump flow. However, as alternatives, a non-return valve 2 may be placed at other locations.

(12) A pressure regulator R is arranged between the high pressure connection P and the flow regulating valve F in order to regulate the pressure upstream of the flow regulating valve F, which pressure is denoted regulator pressure PR and acts at a first connection point 3 located between the pressure regulator R and the flow regulating valve F. A first control conduit 4 is arranged to convey the regulator pressure PR to the pressure regulator R and to act on the same in the closing direction. Preferably, there is also a spring S arranged, which acts constantly on the pressure regulator R in the opening direction.

(13) A second control conduit 5, which includes a first restrictor 6, is positioned between the flow regulating valve F and the motor port connection A. The second control conduit 5 is arranged to convey the load pressure P.sub.L, which acts at the motor port connection A, from a second connection point 7 via the first the restrictor 6 to a third connection point 8, where a first control pressure P.sub.C acts. The first restrictor 6 may advantageously be fixed and independent of the regulation of the flow regulating valve F.

(14) The third connection point 8 is also connected to the pressure regulator R and acts on the same in the opening direction by means of said first control pressure P.sub.C and further, the third connection point 8 is connected to the low pressure connection T, via a second restrictor 9. The second restrictor 9 is preferably adjustably arranged, e.g. such that it is regulated in dependence of the flow regulating valve F and possibly the adjustable second restrictor 9 may be such arranged that the flow through area of the second restrictor 9 decreases when the flow through area of the opening of the flow regulating valve F towards the motor port connection A increases.

(15) The third connection point 8 is also in connection with a shuttle valve 10, which also receives the control pressure from other valve devices and conveys a control pressure to the pump P. The shuttle valve 10 is in a known manner arranged to convey the highest of the incoming control pressures to the pump P, such that the application that for the moment demands the highest pressure governs the pressure of the pump P.

(16) Preferably, the second restrictor 9 may be such arranged that it is fully open when the flow regulating valve F is closed or just barely open, wherein it for a certain position of the flow regulating valve closes, such that it constitutes a restrictor that is continuously decreased as the flow regulating valve continuously opens. Such a performance implies that when the flow regulating valve F is opened to a low degree, the flow downstream will pass via the first restrictor 6 and the second restrictor 9 rather than to the motor port connection A, unless the pressure at the motor port connection A is very low.

(17) The adjustable second restrictor 9 may advantageously be arranged to be electrically regulated, as shown diagrammatically at 9A in FIG. 3. In this manner it is namely possible to customize the valve device 1 and its controls without having to adapt the production for each individual valve. This is due to the fact that the properties of the valve device to a great extent is actually controlled by the characteristics of the second restrictor 9. The different properties may be adapted to the specific application at which the valve device 1 is to be used, but also to special requirements of a specific operator. Further, it is possible through soft ware programming alone to change the properties of an already installed valve device. Hence, the usefulness of the valve device is ameliorated in that e.g. the valve device may be used in several different applications and that it may be adapted in a simple manner to several different special requirements of different specific operators.

(18) A first embodiment of the valve device 1 according to the diagram in FIG. 3 is shown in the longitudinal section in FIG. 4 and in FIG. 5 an alternative diagram for the same embodiment is shown. In FIGS. 4 and 5 the flow regulating valve F constitutes a part of a control valve with a valve spool H. The valve spool H is adjustable between three positions; a first closed position, which is shown in the figures and in which the flow from the high pressure connection P is kept closed by the valve spool H, and two open positions. In the first open position, in which the valve spool H has been displaced to the right in FIG. 4 and downwards in FIG. 5, the flow regulating valve will open gradually and the hydraulic fluid may flow via a first flow opening 18, which is provided on the valve spool H and which connects both the outlet of the pressure regulator R and the first connection point 3 to the second connection point 7, from which a flow may flow past the non-return valve 2 as soon as the pressure in the second connection point 7 exceeds the load pressure P.sub.L, which acts at the motor port connection A. The first flow opening 18 mainly corresponds to the flow regulating valve F in FIG. 3.

(19) Further, the second connection point 7 is in connection with a third connection point 8, via the first the restrictor 6. The adjustable second restrictor 9 is in the embodiment shown in FIG. 4 constituted by a second flow opening 19, of which the flow through area decreases gradually as the flow regulating valve F opens via the first flow opening 18 and as the valve spool H is displaced to the right.

(20) In the shown embodiment, the pressure regulator R has a regulator spool 11 that is located in a valve body with three separate chambers: a right chamber 12, which is in control connection via the control conduit 4 with the first connection point 3; which connection point 3 constitutes a central chamber; and a left chamber 13, in which a spring S is arranged, which in conjunction with the pressure P.sub.C in the left chamber acts in the opening direction on the regulator spool 11, i.e. towards the right in FIG. 4.

(21) A difference with respect to the diagram in FIG. 3 is that in FIGS. 4 and 5 it is illustrated how the cylinder chamber is emptied via the motor port A. When the valve spool is regulated towards the second open position, i.e. to the left in FIG. 4 and upwards in FIG. 5, diversion recesses 14 will connect the motor port connection A to the low pressure connection T. The more the valve spool H is displaced towards the second open position, the greater the flow opening through the diversion recesses 14 becomes.

(22) To the left of the valve spool H in FIG. 4, a double acting spring arrangement 15 is arranged, which acts to keep the valve spool H in the closed central position shown in FIG. 4.

(23) In FIGS. 6-8, an alternative valve device according to the invention is shown in a corresponding manner as the first valve device has been shown in the FIGS. 3-5. The alternative valve device differs in two features only, with respect to the first embodiment of the valve device, whereas mainly these features will be covered in the following description.

(24) The first difference consists in that a third control conduit 16 including a third restrictor 17 is arranged to convey the regulator pressure P.sub.R that acts in the first connection point 3 between the pressure regulator R and the flow regulating valve F to the third connection point 8.

(25) The second difference consists in that a second non-return valve 20 is arranged in the second control conduit 5 in order to prevent a flow from the outlet of the flow regulating valve F to the third connection point 8, via the second connection point 7. Hence, the second non-return valve 20 opens towards the second connection point 7 and conveys a flow in parallel with the flow regulating valve F when the control pressure P.sub.C at the third connection point 8 is greater than the load pressure P.sub.L at the second connection point 7.

(26) This gives advantages in systems with great inertia, such as e.g. when a swinging arm or crane beam is to be moved. When the flow regulating valve F opens in order to let through a flow it will in a conventional valve device initially take a very high pressure to overcome the inertia of the crane beam and make it move. However, as the crane beam works up a velocity the necessary pressure will decrease. The control pressure that is conveyed to the pump will in a conventional system however remain elevated due to the fact that the flow that the pump delivers is much greater than that the cylinder chamber may receive. Hence, a flow will go under a very high pressure to the tank, which flow corresponds to an energy loss. In the invention according to the second embodiment, a flow will instead go from the first connection point 3, via the third and second connection points 8 and 7, respectively, to the motor port connection A, with very low pressure losses as a consequence. At the same time a lower pressure P.sub.C will be conveyed to the pressure regulator R and the pump P, which hence may operate at a lower pressure level.

(27) In FIG. 7, an alternative embodiment of the valve device 1 is shown, in which the third control conduit 16 consists of a through hole that connects the first connection point 3 with the third connection point 8. Centrally on the third control conduit 16 a connection to the second control conduit 6 is provided, which includes a second non-return valve 20 that opens towards the second connection point 7. Hence, with respect to the diagram in FIG. 6 there is a difference, but with respect to the strict functionality there is no difference.

(28) The connection point 8, which in FIG. 6 is illustrated by a dot, may in FIG. 7 instead be said to be constituted by the part of the third control conduit 16 that is located downstream of the third restrictor 17 and is in connection with the first restrictor 6. Generally, the shown diagrams are simplifications that only show parts that are relevant for the invention and above all, the connection points are theoretical points that in practice may be constituted by a part of a conduit or the like.

(29) In FIG. 8, a second diagram of the alternative valve device 1 is shown. The difference in this diagram with respect to the diagram that is shown in FIG. 5 is hence the same as the differences between FIGS. 7 and 4, i.e. the third control conduit 16 that includes a third restrictor 17 and a second non-return valve 20. The third control conduit 16 is not represented in the second open position, i.e. when the valve spool has been displaced upwards, since in this position it is without function.