Patent Publication Number: US-9422838-B2

Title: Control valve for a camshaft adjuster system

Description:
FIELD OF THE INVENTION 
     A control valve for a hydraulic device, in particular central valve of a camshaft adjuster system for reciprocating-piston internal combustion engines, with a valve sleeve which projects into a cavity of a camshaft, wherein a displaceable control piston is arranged in the valve sleeve, said control piston is loaded on one side by means of a spring, which is adjoined by a pressurizing medium line. 
     BACKGROUND 
     Such a control valve with a valve sleeve is known from DE 10 2007 058 491 A1. The control valve is a component of a device for variable adjustment of the control times of gas exchange valves on reciprocating-piston internal combustion engines. It is screwed into a camshaft which is formed to be hollow at the end and, in combination with the control piston, controls the pressurizing medium inflow, the control lines which lead to a camshaft adjuster unit and the pressurizing medium outflow which is connected to a pressurizing medium line. In the case of this control valve, the pressurizing medium inflow is carried out in the region of the outer end of the valve sleeve by a stationary housing part of the internal combustion engine so that the installation and the configuration of the adjuster system are structurally highly restricted. 
     The problem furthermore exists that pressurizing medium can unintentionally flow back out of the control valve or the camshaft adjuster when the reciprocating-piston internal combustion engine is at a standstill, and the drainage of the lines and the adjusting chambers causes an unintentional adjustment of the control times. 
     It is furthermore generally known to supply a hollow camshaft through a bearing connected to a pressurizing medium supply channel, wherein at least one radial supply line is provided from the bearing surface. 
     It is important here for the durability of the camshaft mounting that oil pressure is present at the bearings in as short a time as possible after starting the engine. 
     SUMMARY 
     The object of the invention is to improve a control valve and in particular a valve sleeve so that on one hand the camshaft mounting is supplied quickly enough with pressurizing medium/lubricant and on the other hand the control valve and thus the camshaft adjuster are likewise supplied with pressurizing medium by simple means. The oil volume of the camshaft adjuster system and of the control valve should also be separated from the oil supply of the camshaft. 
     The object of the invention is achieved in that the cavity of the camshaft is connected by means of at least one supply line in the camshaft and by means of a bearing to a pressurizing medium supply channel of the reciprocating-piston internal combustion engine and that the pressurizing medium line is formed as a pressurizing medium inflow line and the pressurizing medium inflow line is connected by means of a pressure line in the camshaft and by means of the bearing to the pressurizing medium supply channel of the reciprocating-piston internal combustion engine. 
     It is ensured as a result that the control valve and the camshaft adjuster are also supplied with pressurizing medium via the bearing and the pressurizing medium supply channel of the reciprocating-piston internal combustion engine independently of the pressurizing medium supply of the camshaft. This involves a significant simplification since the pressurizing medium supply is carried out via a single pressurizing medium supply channel and a bearing, wherein a pressure line is provided from the bearing to the pressurizing medium inflow line and a supply line is provided to the camshaft. It should be expressly pointed out that separate pressurizing medium supplies to the bearing point can also be provided. The bearing preferably is the end bearing of the camshaft adjacent to the camshaft adjuster. 
     In a further configuration of the invention, it is provided that the at least one supply line and the at least one pressure line are arranged next to one another within the bearing radially in the camshaft. As a result, the supply of the camshaft and of the camshaft adjuster is carried out simultaneously via the pressurizing medium supply channel of the reciprocating-piston internal combustion engine and a bearing. 
     Normally, not only one supply line and one pressure line are fixed on grooves on the bearing point of the camshaft, rather several are provided so that pressurizing medium can continuously reach the camshaft and the camshaft adjuster. 
     In a further configuration of the invention, it is provided that the valve sleeve extends within the camshaft at least up to the supply line and that the valve sleeve separates the supply lines from the pressure lines. This is carried out, for example, by means of an O-ring which seals off the valve sleeve from the inner wall of the hollow camshaft. The O-ring is arranged in a groove of the valve sleeve for easier assembly. As a result of the decoupling of the pressurizing medium supply to the control valve and the camshaft adjuster and the camshaft, it is ensured that the camshaft adjuster and the control valve do not drain and that furthermore pressurizing medium is present at the bearings of the camshaft in as short a time as possible after the start of the reciprocating-piston internal combustion engine. The pressurizing medium supply of the camshaft and its bearings is advantageously carried out via at least one radial bore and one axial bore in the valve sleeve which connect the supply line or supply lines to the cavity of the camshaft. The pressurizing medium supply of the control valve and of the camshaft adjuster has a blind bore ( 10 ) at the pressurizing medium inflow line and radial bores. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For further explanation of the invention, reference is made to the drawings in which an exemplary embodiment of the invention is represented in a simplified form. In the drawings: 
         FIG. 1 : shows a section through a control valve with valve sleeve, a camshaft adjuster and a camshaft, and 
         FIG. 2 : shows a section through the control valve with valve sleeve. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIGS. 1 and 2 , in so far as represented in detail,  1  designates a valve sleeve in which a control sleeve  2  is inserted in which itself a control piston  3  is arranged and mounted axially displaceably. The control piston  3  is operatively connected to a spring  4  which is supported on a spring bearing  5 . The spring bearing  5  is supported on the control sleeve  2 . 
     The control piston  3  has a head  6  to which, not represented, an actuator corresponds which can displace the control piston  3  counter to the force of the spring  4  and thus controls cross-sections of the pressurizing medium inflow, of the control lines and the pressurizing medium outflow. The valve sleeve  1  has an extension neck  7  on the inner end of which a thread is incorporated to which the valve sleeve  1  can be screwed into a camshaft  8 . The camshaft  8  is embodied to be hollow. The valve sleeve  1  further carries a camshaft adjuster  9 , not described in greater detail, which is hydraulically operatively connected to the valve sleeve  1 . The valve sleeve  1  furthermore has in its interior a blind bore  10  which is connected to the inner space of the valve sleeve. Radial bores are connected to the blind bore  10 , which radial bores lead to an annular space  11  to which two pressure lines  12  in the camshaft  8  are connected which lead to a groove  13  in the camshaft  8 . The valve sleeve  1  furthermore has an axial bore  14  to which a radial bore  15  is connected which likewise leads to an annular space to which are connected supply lines  16  in the camshaft  8  which extend up to a circumferential groove  17  in the camshaft  8 . An O-ring  18  is installed on the valve sleeve between the radial bore  15  and the bores on the blind bore  10 , which O-ring  18  seals off with the inner wall of the camshaft. The O-ring  18  is itself inserted in a guide groove  19  in order to ensure a reliable guidance of the O-ring  18  during assembly. 
     It is ensured as a result of this configuration of the valve sleeve  1  and the camshaft  8  that a pressurizing medium inflow and outflow is decoupled from the pressurizing medium supply channel of the internal combustion engine via the bearing and the pressure lines  12  and the supply lines  16 . 
     LIST OF REFERENCE NUMBERS 
       1  Valve sleeve 
       2  Control sleeve 
       3  Control piston 
       4  Spring 
       5  Spring bearing 
       6  Head 
       7  Extension neck 
       8  Camshaft 
       9  Camshaft adjuster 
       10  Blind bore 
       11  Annular space 
       12  Pressure lines 
       13  Groove 
       14  Axial bore 
       15  Radial bore 
       16  Supply lines 
       17  Circumferential groove 
       18  O-ring 
       19  Guide groove