Power plants – Pressure fluid source and motor – Expansible chamber type volumetric responsive measuring...
Reexamination Certificate
1999-11-03
2001-05-29
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Expansible chamber type volumetric responsive measuring...
C060S387000
Reexamination Certificate
active
06237331
ABSTRACT:
The invention relates to a hydraulic steering arrangement with a housing, in which an inner control slide and an outer control slide are arranged to be mutually rotational, forming together a variable flow path device between a supply connection device and a working connection device, at least one pressure chamber being arranged between two working slides, connected with both control slides, the volume change of said pressure chamber causing the relative displacement, and with a measuring motor.
A hydraulic steering arrangement of this kind is known from DE 195 46 281 A1.
In such steering arrangements the supply connection device usually comprises a pump connection and a tank connection. The working connection device usually comprises two working connections. Depending on which of the working connections is acted upon by pressure, a connected steering motor is moved in one direction or the other.
The steering arrangement described in the introduction can, on the one hand, be operated by means of a steering handwheel, which is used to rotate the inner control slide in relation to the outer control slide. Thus, a flow path between the pump connection and the corresponding working connection, or between the other working connection and the tank connection, is released under more or less throttling. Thus, hydraulic fluid flows from the pump via the steering motor and back to the tank. At the same time, the hydraulic fluid activates the measuring motor, which rotates the outer control slide in relation to the inner control slide, thus bringing the two control slides back to their initial overlapping, in which the flow path is closed.
On the other hand, the known steering arrangement can also be controlled without a steering handwheel, in that a pressure is applied in the pressure chamber. The pressure leads to a volume expansion, which again causes that the two control slides are moved in relation to each other. The pressure build-up in the pressure chamber can be remote-controlled, so that by means of this arrangement it is also possible to perform a remote control of the steering arrangement.
The invention is based on the task of providing a simple and non-expensive control arrangement, which is based on the remote control principle mentioned above.
In a steering arrangement as described in the introduction, this task is solved in that an intermediary plate is arranged between the measuring motor and the control slides, in which plate at least one fluid channel is arranged to form at least one part of a connection from the pressure chamber to the outside.
With this embodiment it is possible to use the measuring motor and the housing of a steering arrangement, which has until now only been activated by way of a steering handwheel. Also the two control slides can remain substantially unchanged. It is only required either to extend them a little axially to provide them with working slides, to arrange working slides on the control slides, or to connect them in a different way. In other words, a customary steering arrangement can be used, which has proved its performance and in which the dimensioning is appropriate, which steering arrangement can then be remote controlled by means of a volume change induced in a pressure chamber between the two slides. The volume change is induced in that a pressure fluid is either supplied or drawn off through the fluid channel. The corresponding pressure control, that is, the pressure build-up or the pressure reduction can take place on the outside, that is, outside the housing. The remaining parts do not have to be changed, that is, it is not necessary to provide new borings through the known housing or the known measuring motor, to serve as channels for the pressure fluid.
In a preferred embodiment it is provided that the working slides project into the intermediary plate. The only additional component to be provided, is the intermediary plate. This intermediary plate can also be used to provide a space in whose axial extension the pressure chamber can be arranged. Thus, the remaining parts must not be changed. Additionally, the working slide can be acted upon directly via the intermediary plate, without requiring large deflections which cause problems with regard to sealing.
Preferably, the fluid channel ends in an annular chamber, which is formed between the intermediary plate and the outer working slide. Thus, the pressure chamber can also be fed or acted upon from the outside. This provides a very simple way of supply. Axial sealings are only required to a very limited extent. As the annular chamber surrounds the slide on the whole circumference, the supply of the pressure chamber is independent of the rotation position of both working slides.
Preferably, the annular chamber is formed by a groove on the outer circumference of the outer working slide and/or in the inner circumference of the intermediary plate. A groove of this kind at the same time forms a limitation in the axial direction, so that also more than one groove, in particular two grooves, can be provided between the outer slide and the intermediary plate. Such grooves are relatively simple to produce, so that the production costs are limited.
Preferably, two fluid channels are provided, of which each is connected with a group of pressure chambers, the two groups having opposite action directions. In this way the relative displacement between the outer slide and the inner slide can be performed in both directions, meaning that both steering directions can be remote-controlled in the same way. The moment the pressure chambers of one group are acted upon by pressure fluid and expand, the pressure fluid is displaced from the pressure chambers of the other group. This results in two operating opportunities, firstly when building up the pressure and secondly when controlling the outflow of the hydraulic fluid.
Preferably, the connections between the two groups and the outside have substantially the same flow resistance. Thus, the control behaviour in both steering directions is at least approximately the same.
In a preferred embodiment it is provided that the fluid channel ends on the circumference of the intermediary plate. Thus, the fluid channel passes through the intermediary plate from the bore, in which the working slide is arranged, to the outside, that is, substantially radially. An exact radial alignment of the fluid channel is, however, not required. In this embodiment, the fluid channels are exclusively arranged in the intermediary plate. Thus, the working of other parts can be avoided.
In this connection, it is particularly preferred that the intermediary plate, in the area, in which the fluid channel ends outside, has a plane bearing surface. Thus, control elements, for example valves, can be fixed on this bearing surface. The sealing towards connecting parts is simplified when the bearing surface is plane.
In an alternative embodiment it is provided that the fluid channel ends in a bore in the intermediary plate, through which bore a fixing bolt is led, the fixing bolt having a longitudinal bore, which forms an additional part of the connection. In a steering arrangement comprising a control slide part and a measuring motor part, it is necessary to fix the two parts on each other axially, this fixing having to be performed with a certain force to provide the required sealing between these two parts. In known steering arrangements fixing bolts are inserted from an axial side, for example the side of the measuring motor, and then screwed into the control slide part. These fixing bolts can additionally be used to provide a fluid path, which continues the fluid channel and permits a pressure fluid to get from the outside to the inside. Expediently, for this purpose the fixing bolt has an internal bore, as it is easier to fix connecting parts, like for example valves or other lines, to such an internal bore.
In this connection it is advantageous that the fixing bolt, on part of its length, is surrounded by an annular slot, into which at least one radial bore connected with the
Danfoss A/S
Lee Mann Smith McWilliams Sweeney & Ohlson
Ryznic John E.
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