Expansible chamber devices – Relatively movable working members – Interconnected with common rotatable shaft
Patent
1996-12-27
1998-09-29
Thorpe, Timothy
Expansible chamber devices
Relatively movable working members
Interconnected with common rotatable shaft
417269, F04B 120, F03C 106
Patent
active
058133151
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/DK95/00277, filed Jun. 30, 1995.
BACKGROUND OF THE INVENTION
The invention relates to a hydraulic piston machine having a cylinder body, which has at least one cylinder, in which a piston is arranged to move back and forth and bears by way of a slide shoe against a control surface, and having a pressure plate which holds the slide shoe in engagement with the control surface.
Such a hydraulic machine can operate according to the axial piston principle or according to the radial piston principle. In both cases the movement of the piston is controlled by way of a control surface on which the slide shoe lies and over which it is guided on movement of the cylinder body. Since the slide shoes have to be held constantly in engagement with the control surface, the pressure plate has to perform corresponding back and forth movements, for example, pivoting movements, with respect to the cylinder body. This causes a certain amount of friction when the pressure plate is mounted opposite the cylinder body. There is a further region of friction where the slide shoes bear against the pressure plate. There, the relative movement is not as pronounced, but nevertheless still exists. Finally, the slide shoes slide over the control surface, so that here too there is a certain amount of friction.
This friction was not critical provided that the hydraulic fluids used had lubricating properties at the same time. Such hydraulic fluids are formed, for example by oils. Synthetic oils that have been specifically developed for hydraulic machines have especially good properties. However, these synthetic oils have the serious drawback that they are often toxic and are able to escape in the event of the machine being damaged, or even in operation, which leads to considerable environmental pollution.
SUMMARY OF THE INVENTION
The invention is based on the problem of being able to operate a hydraulic piston machine even with hydraulic fluids which have no or poor lubricating properties, for example, with water.
This problem is solved in a machine of the kind mentioned in the introduction in that the pressure plate and/or the control surface is provided with a layer of a friction-reducing plastics material at least in one of the regions with which in operation they rub against other parts.
The "friction-reducing" property is, of course, always with respect to the material of the counterpart against which the pressure plate or the control surface rubs. In the case of the control surface this is the material of the slide shoe. In the case of the pressure plate it is the material of the slide shoe and the material of a pressure-applying arrangement, for example, in the case of an axial piston machine, a ball-and-socket joint, which biases the pressure plate with force towards the control surface. Suitable plastics material for the layer are in particular materials from the group of high-strength thermoplastic plastics materials based on polyarylether ketones, for example, polyether ether ketones, polyamides, polyacetals, polyaryl ethers, polyethylene terephthalates, polyphenylene sulphides, polysulphones, polyether sulphones, polyether imides, polyamideimide, polyacrylates, phenol resins, such as novolak resins, or similar substances; glass, graphite, polytetrafluoroethylene or carbon, especially in fibre form, can be used as fillers. When using such materials, it is possible to use even water as hydraulic fluid.
Because only a layer of the friction-reducing plastics material is provided, the parts provided with the layer can be adopted virtually unchanged compared with a construction without the layer. The strength in particular can be maintained if the layer is applied to a core of stronger material. The problem of keeping the layer on the core is largely offset in the case of the pressure plate and control surface because both parts have relatively large flat areas to which this layer is able to cling with the necessary reliability. In the case of parts with a more complex geometry, for example, slide
REFERENCES:
patent: 3183848 (1965-05-01), Raymond
patent: 3453965 (1969-07-01), Heinrich
patent: 4617856 (1986-10-01), Miller et al.
patent: 5017095 (1991-05-01), Burgess et al.
patent: 5601009 (1997-02-01), Jepsen et al.
patent: 5685215 (1997-11-01), Jepsen et al.
Kristensen Egon
Martensen Lars
Olesen Sten Jensen
Danfoss A/S
Kim Ted
Thorpe Timothy
LandOfFree
Hydraulic piston machine having sheathing plastic material for r does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic piston machine having sheathing plastic material for r, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic piston machine having sheathing plastic material for r will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-677551