Adjustable rotary pump with reduced wear

Abstract

A rotary pump having a variable delivery volume, comprising: a casing; a delivery chamber formed in the casing; at least one delivery rotor which is rotatable in the delivery chamber; an actuating member which is arranged facing a front face of the delivery rotor or surrounds the delivery rotor, and is moveable in the casing for adjusting the delivery volume; the actuating member chargeable with an actuating force which is dependent on a fluid requirement; a track which is formed in the casing and guides the actuating member on an actuating member sliding surface in a sliding contact; and a sliding material which forms at least one of the track and the actuating member sliding surface.

1 . A rotary pump having a variable delivery volume, comprising: 
 a casing;    a delivery chamber formed in the casing and comprising an inlet for a fluid on a low-pressure side and an outlet for the fluid on a high-pressure side of the pump;    at least one delivery rotor rotatable in the delivery chamber about a rotational axis;    an actuating member which is arranged facing a front face of the delivery rotor or surrounds the delivery rotor, and is moveable in the casing for adjusting the delivery volume; the actuating member chargeable, in the direction of its mobility, with an actuating force which is dependent on a fluid requirement;    a track which is formed in the casing and guides the actuating member on an actuating member sliding surface in a sliding contact; and    a sliding material which forms at least one of the track and the actuating member sliding surface.    
   
   
       2 . The rotary pump according to  claim 1 , wherein the sliding material consists of at least one of plastic, ceramic, nitride, a nickel-phosphorus compound, a sliding varnish, a DLC coating, a Ferroprint coating or a nano-coating.  
   
   
       3 . The rotary pump according to  claim 1 , wherein the sliding material exhibits an adhesion energy which is at most half an adhesion energy of aluminum.  
   
   
       4 . The rotary pump according to  claim 1 , wherein: 
 the actuating member, another actuating member and the delivery rotor are part of an adjusting unit which can be moved as a whole back and forth in the casing;    the actuating members are each arranged facing one of the front faces of the delivery rotor, and another track is formed in the casing which guides the other actuating member on its actuating member sliding surface in a sliding contact; and    wherein at least one of the other track and the actuating member sliding surface of the other actuating member consists of the sliding material.    
   
   
       5 . The rotary pump according to  claim 1 , wherein the sliding material is a thermoplast modified to lubrication.  
   
   
       6 . The rotary pump according to  claim 1 , wherein the sliding material is a polymer compound of at least one heat-resistant polymer filled with fibrous material and a sliding additive.  
   
   
       7 . The rotary pump according to  claim 6 , wherein the sliding material comprises at least one of graphite, a fluoropolymer and PTFE.  
   
   
       8 . The rotary pump according to  claim 6 , wherein the proportion of polymer is at least 60% by weight and at most 80% by weight.  
   
   
       9 . The rotary pump according to  claim 6 , wherein the proportion of the sliding additive is at least 10% by weight and at most 30% by weight.  
   
   
       10 . The rotary pump according to  claim 6 , wherein the proportion of the fibrous material is at least 5% by weight and at most 15% by weight.  
   
   
       11 . The rotary pump according to  claim 6 , wherein the fibrous material comprises or consists of carbon fibers.  
   
   
       12 . The rotary pump according to  claim 1 , wherein the sliding material is a plastic, and a base material of the plastic is a polymer including copolymer, a mixture of polymers or a polymer blend from the group consisting of polyether sulphone (PES), polysulphone (PSU), polyphenylene sulfide (PPS), polyether ketones (PAEK, PEK, PEEK), polyamide (PA) and polyphthalamide (PPA).  
   
   
       13 . The rotary pump according to  claim 1 , wherein at least one of the actuating member sliding surface and the track is formed by a metal-ceramic layer.  
   
   
       14 . The rotary pump according to the preceding claim, wherein the layer is a ceramic layer or a smooth ceramic layer.  
   
   
       15 . The rotary pump according to  claim 14 , wherein the layer contains PTFE.  
   
   
       16 . The rotary pump according to  claim 1 , wherein nitrided steel or TiCN forms one of the track and the actuating member sliding surface.  
   
   
       17 . The rotary pump according to  claim 1 , wherein a casing portion comprising the track at least substantially consists of metal or is formed from a metal as a substrate material and a sliding layer of the sliding material forming the track is applied to the substrate material or is formed by modifying the substrate material.  
   
   
       18 . The rotary pump according to  claim 17 , wherein a casting material forms the casing portion or the substrate material of the casing portion.  
   
   
       19 . The rotary pump according to  claim 18 , wherein the casting material is a die casting material, a chill casting material or a sand casting material exhibiting a corresponding structure.  
   
   
       20 . The rotary pump according to  claim 1 , wherein the actuating member including the actuating member sliding surface consists at least substantially of metal or is formed from a metal as a substrate material and a sliding layer of the sliding material forming the actuating member sliding surface is applied to the substrate material or is formed by modifying the substrate material.  
   
   
       21 . The rotary pump according to  claim 20 , wherein a casing portion comprising the track at least substantially consists of metal or is formed from a metal as a substrate material and a sliding layer of the sliding material forming the track is applied to the substrate material or is formed by modifying the substrate material, and wherein the metal of the casing portion and the metal of the actuating member contain the same metallic element at least as their main constituent.  
   
   
       22 . The rotary pump according to  claim 17 , wherein the metal is aluminum or an aluminum-based alloy or another light metal.  
   
   
       23 . The rotary pump according to  claim 17 , wherein a ceramic material of the substrate material forms the sliding layer.  
   
   
       24 . The rotary pump according to  claim 17 , wherein the ceramic material of the substrate material is aluminum oxide (Al 2 O 3 ).  
   
   
       25 . The rotary pump according to  claim 17 , wherein the metal is aluminum or an aluminum-based alloy which contains silicon, or the metal is an aluminum-based alloy containing at least one of copper and iron.  
   
   
       26 . The rotary pump according to  claim 1 , wherein at least one of the actuating member and the casing, or at least a casing portion which forms the track, is formed from the sliding material.  
   
   
       27 . The rotary pump according to  claim 1 , wherein the actuating force is arranged to counteract an elasticity member; or the actuating member is an actuating piston which can be charged with the fluid of the high-pressure side.  
   
   
       28 . The rotary pump according to  claim 1 , wherein the delivery rotor and the actuating member can be axially moved in relation to the rotational axis.  
   
   
       29 . The rotary pump according to  claim 1 , comprising another delivery rotor which can be rotated in the delivery chamber about another rotational axis, wherein the delivery rotors are in delivery engagement with each other.  
   
   
       30 . The rotary pump according to  claim 1 , wherein the pump is an external-axle rotary pump or an external toothed wheel pump.  
   
   
       31 . A method for manufacturing the rotary pump according to  claim 1 , wherein: 
 a) a casing portion forming the track is formed from a light metal;    b) the actuating member is formed from the same or a different light metal; and    c) the casing portion for producing the track or the actuating member for producing the actuating member sliding surface is coated with the sliding material, or the light metal of the casing portion or the light metal of the actuating member is or are modified at the surface into the sliding material.    
   
   
       32 . The method according to the preceding claim, wherein at least one of the casing portion and the actuating member is ceramised in the region of the track or the actuating member sliding surface, preferably anodized, nitrided or provided with a plastic coating, a sliding varnish, a tungsten carbide coating, a Ferroprint coating or a nano-coating.  
   
   
       33 . The method according to  claim 25 , wherein the casing portion is formed from an aluminum-based alloy by sand casting, chill casting or die casting, and the track is preferably formed by mechanically machining the casting material.  
   
   
       34 . The method according to  claim 25 , wherein the actuating member for forming the actuating member sliding surface is coated with a plastic modified to lubrication.