Control valve for a hydraulic elevator

Abstract: Control valve for a hydraulic elevator, provided with a speed regulating plug (2) moving with the flow of the hydraulic fluid, the position of the speed regulating plug determining the flow of hydraulic fluid into the actuating cylinder of the elevator, and a hydraulic channel system (1) forming an essentially closed loop. A problem with hydraulic elevators, in situations when the elevator is approaching a landing, is the difficulty of achieving a constant deceleration regardless of variations in the temperature of the hydraulic fluid. The invention solves this problem in that the hydraulic channel system (1) is provided with a flow resistance component (9) placed near either end of the speed regulating plug, the setting of said component being varied on the basis of the temperature of the hydraulic fluid.

Description: The present invention relates to a control valve for a hydraulic elevator, in accordance with the preamble of claim 1. The viscosity of oil, which is the hydraulic fluid most commonly used in hydraulic elevators, is reduced by about a decade as the oil is heated from the lowest working temperature to the highest working temperature. In the case of an elevator provided with a pressure-controlled ON-OFF-type control valve, this involves an increase in deceleration with an increase in temperature, because the control valve is closed faster due to a reduced kinetic resistance of the speed regulating plug. A problem in this case is that the elevator, when working at "normal operating temperature", has an excessively long creeping time when arriving at a landing. This is because the distance of the deceleration vanes in the hoistway from the landing must be adjusted for the lowest oil temperature to avoid overtravel. In principle, the deceleration is based on a hydromechanical time reference. After the supply of electricity to the magnetic valve has been interrupted, a spring pushes the plug of the control valve towards the closed position while a throttle in the hydraulic circuit retards the closing of the valve. It is important to notice that the closing speed depends on the viscosity of the oil even in the case of a fully viscosity-independent throttle, because the kinetic resistance of the valve plug depends on the viscosity. As the resistance diminishes, the pressure difference across the throttle increases, involving an increase in the flow towards the speed regulating plug and therefore an increase in the plug speed. US patent 4 194 534 describes a compensating valve for use with a hydraulic elevator valve, said compensating valve being of such character that there will be an automatic adjustment in performance of the hydraulic elevator valve when there is a change of temperature in the hydraulic fluid. The compensating valve comprises temperature responsive discs such that they flatten out at increased temperature, permitting a stem to move, thereby to close off one or more ports, the result of which is a reduction in flow of hydraulic fluid through the compensating valve. The object of the present invention is to create a control valve for a hydraulic elevator which achieves compensation of variations in the viscosity of the hydraulic fluid in a simple manner so as to keep the creeping distance essentially constant all the time The control valve of the invention is characterized by the features comprised in claim 1. The other embodiments of the control valve of the invention are characterized by what is presented in the subclaims. The invention has the advantage that it provides a control valve for hydraulic elevators that is independent of variations in the viscosity of the oil, thus ensuring a reliable deceleration of the elevator and making it more comfortable for the passengers at a low cost. In the following, the invention is described in detail by the aid of examples of preferred embodiments, reference being made to the drawing attached, wherein: Fig. 1 presents a diagram of a hydraulic channel system provided with a flow resistance component as provided by the invention. Fig. 2 presents a sectioned and more detailed view of the flow resistance component of the invention, and Figs. 3 and 4 present two other embodiments of the flow resistance component of the invention, in a sectioned and more detailed view. Fig. 1 shows part of the conventional hydraulic channel system 1 of the control valve of a hydraulic elevator, comprising a speed regulating plug 2 which moves in an essentially closed space 3 provided for it. The hydraulic fluid in the main flow channel flows through this space 3, from the inflow channel 4 to the outflow channel 5, which leads to the actuating cylinder of the elevator. The middle part of the speed regulating plug is of an essentially conical form. Thus, when the plug moves longitudinally to the left (as seen in Fig. 1), it throttles the flow 4, 5. The flow is largest when the plug is in its extreme right position. When the electricity supply to the distributing valve 6 is interrupted, it returns to the position shown in Fig. 1. The elevator speed will now decrease because the spring 8 pushes the speed regulating plug 2 towards the closed position, i.e. to the left in Fig. 1. As a result of this movement of the speed regulating plug, the oil used as hydraulic fluid will pass the plug by its left-hand end and flow in the hydraulic channel system 1 through the distributing valve 6 and the flow resistance component 9 into the spring space to the right of the plug. The flow resistance component presents a resistance to this flow, thus determining the speed of movement of the speed regulating plug. 2 In the position shown in Fig. 1, the 3/2-way distributing valve 6 provided in the hydraulic channel system 1 permits a secondary hydraulic fluid flow towards the speed regulating plug. In this situation, the elevator is being decelerated. As the temperature of the hydraulic fluid rises during use, its viscosity is reduced, thus reducing the kinetic resistance of the speed regulating plug. Consequently, the pressure difference Δp₁ increases, increasing the flow V₁ . Therefore, the speed control valve is closed faster, resulting in a greater rate of deceleration of the elevator. This variation in deceleration is one of the drawbacks of previously known solutions. In the other position of the distributing valve 6, the secondary hydraulic fluid is allowed to flow into the tank 7 until the speed regulating plug 2 has reached its fully open position and the elevator is travelling at full speed. Furthermore, the hydraulic channel system is provided with a flow resistance component 9 reacting to the temperature of the hydraulic fluid, said component being placed between the distributing valve 6 and the speed regulating plug 2. Inside the frame of the flow resistance component is a needle valve having a body made of brass or other suitable metal. Fig. 2 shows a more detailed view of the needle valve. The secondary hydraulic fluid flows into the needle valve as inflow 11 and out of the valve as outflow 12, which goes to the speed regulating plug 2. The flow is throttled between the conical end of the needle 13 and the choke piece 14. The mouth of the choke piece, too, is of a conical form. After the conical mouth there is the narrowest part of the choke, the diameter of which essentially corresponds to the largest diameter of the needle. The range of motion of the needle is approx. 1 mm in the axial direction, and the flow through the choke-changes accordingly. The deceleration of the hydraulic elevator is varied by varying the angle of taper of the needle end. The needle movement is produced by means of a regulator consisting of a hollow brass bellows 15 housed in a bore provided in the brass body 10 of the valve. The hollow inside the brass bellows is filled with a liquid 18, e.g. spirit or other alcohol, which reacts to variations in the temperature of the hydraulic fluid by expanding or contracting, causing the needle 13 of the needle valve to move accordingly. The brass body of the needle valve is fastened to the body of the flow resistance component by means of a sealing nut 16, and the liquid filling in the brass bellows is retained in the bellows by a stopper 17. The flow resistance component controlled by the temperature of the hydraulic fluid is used in the deceleration of a hydraulic elevator to compensate the variations in deceleration resulting from changes in temperature. The deceleration is varied by varying the angle of taper of the needle end. The compensation works as follows. As the temperature of the hydraulic fluid 11 flowing into the flow resistance component rises during use and its viscosity decreases, i.e. its fluidity increases, the brass bellows 15 and the liquid filling 18 inside it are heated. As the liquid gets warmer, it expands and extends the bellows. Therefore, the needle is moved to the left as seen in Fig. 2, i.e. towards the choke piece 14. Since the needle has a conical end and the inner surface of the choke piece also has a conical shape, the flow of the hydraulic fluid is choked and the rate of the flow to the speed regulating plug remains essentially constant. It is obvious to a person skilled in the art that the invention is not restricted to the examples of its embodiments described above, but that it may instead be varied within the scope of the following claims. Thus, the brass bellows of the flow resistance component can be replaced with other suitable solutions. Fig. 3 illustrates a solution in which the brass bellows with a liquid filling has been replaced by an elastomeric bellows 19 which is in contact with the liquid space 18. Similarly, Fig. 4 shows a solution in which the bellows has no liquid space at all inside it. Instead, the element reacting to temperature consists of an elastomer 20 alone. E.g. a suitable silicone can be used for this purpose. The spherical surface 21 of the elastomer permits a large needle motion with changes in temperature.

Claims: Control valve for a hydraulic elevator, through which a main flow (4,5) of a hydraulic fluid passes and which is provided with a speed regulating plug (2) moving with a secondary flow of hydraulic fluid, the position of the speed regulating plug determining the main flow of hydraulic fluid into an actuating cylinder of the hydraulic elevator, and a system of hydraulic channels (1) in which the secondary hydraulic fluid flows, said hydraulic channels being connected to each end of the speed regulating plug and communicating with the main hydraulic circuit, with one flow component flowing out of the control valve at one end of the speed regulating plug and one flow component flowing into the control valve at the other end of the speed regulating plug wherein the hydraulic channel system (1) is provided with a flow resistance component (9) placed near either end of the speed regulating plug, the setting of said flow resistance component being varied on the basis of the temperature of the hydraulic fluid, characterized in that the flow resistance component (9) is a needle valve consisting of a body (10), a choke piece (14) and a needle (13) inside the body, the needle being connected to an adjusting element (15, 18-20). Control valve according to claim 1, characterized in that the adjusting element is a hollow bellows (15) made of a metal,e.g.brass (bronze), and filled with a liquid (18), e.g. spirit or equivalent. Control valve according to claim 1, characterized in that the adjusting element is an elastomeric bellows (19) forming a hollow space in the body (10), said space being filled with a liquid (18). Control valve according to claim 1, characterized in that the adjusting element is an elastomeric component (20) having a spherical surface (21) on the side facing the choke piece (14), said surface being provided with a needle (13) so fitted that it will move towards the choke piece and away from it as the surface (21) moves. Control valve for a hydraulic elevator according to any one of claims 1 -4, characterized in that the needle (13) of the needle valve has a conical end, that the needle moves inside the choke piece (14), which is provided with a suitable hole, within a range of approx. 1 mm, and that the characteristic of deceleration of the elevator is varied by varying the angle of taper of the needle end.

Inventors: PELTO-HUIKKO RAIMO, PELTO-HUIKKO, RAIMO
Applicants: KONE ELEVATOR GMBH
Application year: 1990
Main classification: B66B1
IPC codes: B66B1, B66B9, F16K31