Patent Publication Number: US-2015059667-A1

Title: Oil supply device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority of Korean Patent Application Number 10-2013-0106320 filed Sep. 4, 2013, the entire contents of which application is incorporated herein for all purposes by this reference. 
     BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates, in general, to oil supply devices, and, more particularly, to an oil supply device, intended to supply oil to a device for advancing or retarding a cam, in addition to supplying oil to a journal of a cam shaft via a simplified path. 
     2. Description of Related Art 
     Among various methods for improving the performance of a vehicle, there is used a method of varying the intake and exhaust timing of an engine depending on a load and thereby creating an optimum combustion environment. 
     As a representative device for implementing the above method, continuous variable valve timing (CVVT) is proposed. Here, the CVVT is a device that varies the phase of an intake cam or an exhaust cam to regulate the overlapping of a valve and thereby avoid a reduction in torque at low and middle speeds, providing better fuel efficiency at low and middle speeds and reduce harmful exhaust gas. 
     Generally, as shown in  FIG. 1 , the CVVT includes a continuous variable valve timing unit  20  that is connected to a cam shaft to advance or retard the cam shaft depending on the inflow of oil, and an oil control valve  10  that applies oil to the continuous variable valve timing unit  20  to substantially control the continuous variable valve timing unit  20 . 
     The oil control valve  10  receives oil from an oil pump and supplies the oil to the continuous variable valve timing unit  20 . Since the oil control valve  10  and the continuous variable valve timing unit  20  are separately operated, a plurality of paths should be essentially required to connect respective parts to each other. 
     However, in the case where a distance between the oil control valve  10  and the continuous variable valve timing unit  20  is long, a path connecting them to each other is inevitably lengthened and is complicated. Further, if foreign matter enters the path, the oil cannot flow smoothly, so that several problems occur in terms of quality. For example, the starting of a vehicle may be interrupted. 
     Furthermore, the length of the path is inevitably increased, so that it is impossible to operate the CVVT immediately after starting. 
     The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose an oil supply device that simplifies a path connected with an oil control valve and allows oil to pass through an interior of a hollow cam shaft using the hollow cam shaft, thus reducing the number of paths applied to a cam shaft journal. 
     Various aspects of the present invention provide for an oil supply device, including a plurality of hollow cam shafts having through holes that pass in a longitudinal direction from interior to exterior thereof, cam shaft journals provided on every position at which the through holes are formed, each of the cam shaft journals having a path connected with an associated through hole and being coupled with a cylinder head; and a shaft side path formed to supply oil into each of the hollow cam shafts after the oil sequentially passing from an oil pump through an associated cam shaft journal and an associated through hole. 
     The shaft side path may be connected to any one of the plurality of cam shaft journals to supply oil into an associated hollow cam shaft, and the supplied oil may pass through the interior of the hollow cam shaft, such that the oil flows out of the cam shaft through the through holes other than the through hole into which the oil is introduced, thus lubricating between the cam shaft journal and the hollow cam shaft. 
     The oil supply device may further include a continuous variable valve timing unit connected at a central portion thereof to a first end of the hollow cam shaft, with a path defined in the continuous variable valve timing unit; and an oil control valve passing through the central portion of the continuous variable valve timing unit and coupled axially with the first end of the hollow cam shaft, with a path defined in the oil control valve to be connected with the path in the continuous variable valve timing unit. 
     The oil supply device may further include an oil-control-valve side path formed to allow the oil to pass from the oil pump through the cylinder head into the first end of the hollow cam shaft. 
     The hollow cam shaft may further include on the first end thereof a hole that connects the interior of the hollow cam shaft with the exterior thereof, the oil-control-valve side path may be connected to the hole to allow the oil to be introduced into the hollow cam shaft, and the introduced oil may be supplied to the oil control valve inserted into the first end of the hollow cam shaft. 
     The hollow cam shaft may include on the first end thereof an axial path formed in an axial direction of the hollow cam shaft, a first end of the axial path being connected to the path in the continuous variable valve timing unit, a second end thereof being connected to the oil-control-valve side path. 
     The oil supplied through the oil-control-valve side path may pass through the axial path and flow to the path in the continuous variable valve timing unit, and the oil flowing into the path in the continuous variable valve timing unit may flow again into the path defined in the oil control valve, so that the oil is supplied to the oil control valve. 
     A check valve may be provided in the path defined in the continuous variable valve timing unit, so that, if a pressure exceeds a preset level after the path defined in the continuous variable valve timing unit is filled with the oil, the check valve is opened to allow the oil to be introduced into the path defined in the oil control valve. 
     A hollow may be formed in the oil control valve in a longitudinal direction of the oil control valve in such a way as to be open towards the interior of the hollow cam shaft, and a connecting hole may be provided in the oil control valve to connect the hollow with the exterior of the oil control valve. 
     The shaft side path may be connected to the cam shaft journal that is nearest to the connecting hole, so that the oil flows sequentially through the cam shaft journal, the through hole and the connecting hole into the hollow, and thereafter may be supplied through the hollow into the hollow cam shaft. 
     A control valve may be provided in the hollow at a position opposite to the hollow cam shaft in such a way as to be near to the connecting hole, and, when the oil introduced through the connecting hole exceeds a preset pressure in the hollow, the control valve may be opened, so that the oil may be supplied to the path defined in the oil control valve. 
     As is apparent from the above description, the oil supply device is advantageous in that the path extending from the oil pump to the oil control valve is simplified in structure, thus allowing oil to flow smoothly and considerably reducing the occurrence of foreign matter. 
     Further, the oil supply device is advantageous in that oil can be supplied directly to the oil control valve through the cam shaft and the continuous variable valve timing unit without a separate path, thus reducing the length of the path and increasing the operating speed of the CVVT. 
     The present methods and apparatuses have other features and advantages apparent from the accompanying drawings, incorporated herein, and below Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a conventional CVVT path; 
         FIG. 2  is a view showing a configuration of an exemplary oil supply device according to the present invention; 
         FIG. 3  is a view showing a configuration of an exemplary oil supply device according to the present invention; and 
         FIG. 4  is a view showing a configuration of an exemplary oil supply device according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
       FIG. 2  is a view showing a configuration of an oil supply device according to various embodiments of the present invention. The oil supply device includes a plurality of hollow cam shafts  100 , cam shaft journals  120 , and a shaft side path  130 . Each hollow cam shaft  100  has a through hole  110  that passes in a longitudinal direction from an interior to an exterior thereof. One cam shaft journal  120  is provided on every position at which the through hole  110  is formed. The cam shaft journal  120  has a path connected with the through hole  110 , and is coupled with a cylinder head. The shaft side path  130  is formed to supply oil into the hollow cam shaft  100  after sequentially passing from an oil pump through the cam shaft journal  120  and the through hole  110 . 
     In this respect, the shaft side path  130  is connected to any one of the plurality of cam shaft journals  120  to supply the oil into the hollow cam shaft  100 , and the supplied oil passes through the interior of the hollow cam shaft  100 , such that the oil flows out of the cam shaft  100  through the through holes  110  other than the through hole  110  into which the oil is introduced, thus lubricating between the cam shaft journal  120  and the hollow cam shaft  100 . 
     However, it is not necessary for the shaft side path  130  to be connected to any one cam shaft journal  120 . The shaft side path  130  may be connected to the plurality of cam shaft journals  120  to allow oil to be supplied through several through holes  110  into the hollow cam shaft  100 . 
     As such, by using the hollow cam shafts  100  and supplying oil through any one of the plurality of cam shaft journals  120 , it is unnecessary to install independent paths at respective cam shaft journals  120 , thus achieving the simplification of the entire path. 
     Meanwhile, the oil supply device may further include a continuous variable valve timing unit  200  that is connected at a central portion thereof to a first end of the hollow cam shaft  100 , with a path defined in the continuous variable valve timing unit  200 , and an oil control valve  300  that passes through the central portion of the continuous variable valve timing unit  200  and is coupled axially with the first end of the hollow cam shaft  100 , with a path defined in the oil control valve  300  to be connected with the path in the continuous variable valve timing unit  200 . 
     The oil supply device may further include an oil-control-valve side path  400  that is formed to allow the oil to pass from the oil pump through the cylinder head into the first end of the hollow cam shaft  100 . 
     As such, the oil supply device further includes the oil-control-valve side path  400  to allow the oil to be rapidly introduced into the oil control valve  300 . This naturally improves an initial driving speed of the continuous variable valve timing unit  200 . 
     Further, the hollow cam shaft  100  further includes on the first end thereof a hole  140  that connects the interior of the hollow cam shaft  100  with the exterior thereof. The oil-control-valve side path  400  is connected to the hole  140  to allow the oil to be introduced into the hollow cam shaft  100 , and the introduced oil is supplied to the oil control valve  300  inserted into the first end of the hollow cam shaft  100 . 
     Specifically, a through path is formed in the oil control valve  300  in a longitudinal direction of the oil control valve  300 . The through path is opened to the interior of the hollow cam shaft  100 , so that the oil introduced into the hollow cam shaft  100  through the hole  140  can flow into the oil control valve  300 . 
     The interior of the hollow cam shaft  100  may be separated into a space connected with the oil-control-valve side path  400  and a space connected with the shaft side path  130 . Such a configuration prevents oil introduced through the oil-control-valve side path  400  from unnecessarily flowing into the space connected with the shaft side path  130 , thus rapidly increasing oil pressure of the space connected with the oil-control-valve side path  400  and rapidly driving the continuous variable valve timing unit  200 . 
     Further, the inflow of oil through the shaft side path  130  is unnecessary, so that oil does not flow into the space connected with the oil-control-valve side path  400 , thus rapidly increasing the oil pressure of the space connected with the shaft side path  130  and allowing the cam shaft journal  120  to be rapidly lubricated. 
     Meanwhile, as for the oil returned again after it has been used to drive the continuous variable valve timing unit  200 , a separate drain hole may be provided on a side of the oil control valve  300  to discharge the oil to the cylinder head. 
     As such, the oil can be introduced directly into the oil control valve  300  through the interior of the oil control valve  300  of the hollow cam shaft  100 , so that it is unnecessary to provide a separate path, the path for introducing the oil into the oil control valve  300  can be simplified, and the length of the path and the operation time can also be reduced considerably. 
       FIG. 3  is a view showing a configuration of an oil supply device according to various embodiments of the present invention. The configuration of  FIG. 3  remains the same as that described above in that the cam shaft journal  120  is lubricated through the shaft side path  130  and the interior of the hollow cam shaft  100  and the oil-control-valve side path  400  is provided. However, the configuration of  FIG. 3  is different from that of  FIG. 2  in a process of introducing the oil into the oil control valve  300 . 
     Specifically, the hollow cam shaft  100  may include on the first end thereof an axial path  180  that is formed in an axial direction of the hollow cam shaft  100 . A first end of the axial path  180  is connected to the path in the continuous variable valve timing unit  200 , while a second end thereof is connected to the oil-control-valve side path  400 . 
     Here, the axial path  180  is provided on the first end of the hollow cam shaft  100 . The axial path  180  is not provided in the hollow cam shaft  100  but is formed on the hollow cam shaft  100  itself, so that oil introduced through the oil-control-valve side path  400  does not enter the hollow cam shaft  100 , but flows through the axial path  180  to the continuous variable valve timing unit  200 . 
     Further, the oil supplied through the oil-control-valve side path  400  passes through the axial path  180  and flows to the path  220  in the continuous variable valve timing unit  200 , and the oil flowing into the path in the continuous variable valve timing unit  200  flows again into the path defined in the oil control valve  300 , so that the oil can be supplied to the oil control valve  300 . 
     Here, the reason why the oil is introduced into the continuous variable valve timing unit  200  prior to the oil control valve  300  is because the continuous variable valve timing unit  200  is first filled with the oil and then the oil is transmitted to the oil control valve  300 . This can increase the operating speed of the continuous variable valve timing unit  200 . 
     To be more specific, the continuous variable valve timing unit  200  is first filled with the oil. Thus, even if a small amount of oil is applied when the oil is later applied through the oil control valve  300 , the continuous variable valve timing unit  200  is already filled with oil, so that the continuous variable valve timing unit  200  can be rapidly operated. 
     If oil is applied to the oil control valve  300  without applying oil to the continuous variable valve timing unit  200 , and thereafter the continuous variable valve timing unit  200  starts to be filled with oil, the continuous variable valve timing unit  200  cannot be driven properly while it is filled with oil. Thus, the driving of the continuous variable valve timing unit  200  is considerably delayed. In order to solve the problem, the continuous variable valve timing unit  200  may be first filled with oil. 
     Meanwhile, in order to first fill oil in the continuous variable valve timing unit  200 , a check valve  210  is provided in the path defined in the continuous variable valve timing unit  200 , so that, if a pressure exceeds a preset level after oil fills the path in the continuous variable valve timing unit  200 , the check valve  210  is opened, thus allowing the oil to flow into the path defined in the oil control valve  300 . 
     As for oil returned again after it being used to drive the continuous variable valve timing unit  200 , a separate drain hole may be provided on a side of the oil control valve  300  to discharge oil to the cylinder head. 
       FIG. 4  is a view showing a configuration of an oil supply device according to various embodiments of the present invention. The configuration of  FIG. 4  remains the same as that described above in that the cam shaft journal  120  is lubricated through the shaft side path  130  and the interior of the hollow cam shaft  100  and the oil-control-valve side path  400  is provided. However, the configuration of  FIG. 4  is different from that of  FIGS. 2 and 3  in a process of introducing the oil into the oil control valve  300 . 
     Specifically, a hollow  310  may be formed in the oil control valve  300  in a longitudinal direction of the oil control valve  300  in such a way as to be open towards the interior of the hollow cam shaft  100 , and a connecting hole  320  may be provided in the oil control valve  300  to connect the hollow  310  with the exterior of the oil control valve  300 . 
     Further, the shaft side path  130  is connected to the cam shaft journal  120  that is nearest to the connecting hole  320 , so that the oil flows sequentially through the cam shaft journal  120 , the through hole  110  and the connecting hole  320  into the hollow  310 , and thereafter is supplied through the hollow  310  into the hollow cam shaft  100 . 
     That is, the connecting hole  320  may be formed to coincide with or approach the through hole  110  that is nearest to the oil control valve  300 , among the plurality of through holes  110 . When the connecting hole  320  is located near to the through hole  110 , a predetermined space may be defined between an outer circumference of the oil control valve  300  and an inner circumference of the hollow cam shaft  100  to allow oil to be introduced through the through hole  110  into the connecting hole  320 . 
     The reason why oil passes through the oil control valve  300  into the hollow cam shaft  100  is as follows: a separate path for supplying oil to the oil control valve  300 , that is, the oil-control-valve side path  400  is not formed, and both the oil control valve  300  and the plurality of cam shaft journals  120  are supplied with oil through the shaft side path  130 . Since one path can be eliminated, the entire path is further simplified. Thereby, an error that may occur due to the path can be reduced, and cost for creating a path can be also reduced. 
     Thus, in order to allow oil to be introduced into the oil control valve  300 , a pressure valve  330  is provided in the hollow  310  at a position near to the connecting hole  320  in such a way as to be opposite to the hollow cam shaft  100 . When oil introduced through the connecting hole  320  exceeds a preset pressure in the hollow  310 , the pressure valve  330  may be opened to supply oil to the path in the oil control valve  300 . 
     In order for oil to create pressure sufficient to open the pressure valve  330  in the hollow  310 , it is necessary to adjust an inner diameter of the hollow  310  so that all the oil introduced through the connecting hole  320  is not discharged through the hollow  310  to the hollow cam shaft  100 . That is, the oil introduced into the hollow  310  should create a set pressure between the connecting hole  320  and the pressure valve  330 . This is possible by adjusting the inner diameter of the hollow  310 . 
     As such, the reason why the pressure valve  330  is installed therein is because it provides directivity to the flow of oil. If oil flows into the oil control valve  300  at first, the cam shaft journal  120  is not lubricated smoothly at an initial stage, so that the hollow cam shaft  100  may be undesirably damaged. 
     Thus, the pressure valve  330  is provided to allow a predetermined amount of oil to flow into the hollow cam shaft  100  in advance, thus enabling the cam shaft journal  120  to be smoothly lubricated and simultaneously rapidly increasing oil pressure between the connecting hole  320  and the pressure valve  330 , therefore allowing oil to be introduced into the oil control valve  300  within a short period of time. 
     As for oil returned again after it has been used to drive the continuous variable valve timing unit  200 , a separate drain hole may be provided on a side of the oil control valve  300  to discharge oil to the cylinder head. 
     As described above, the present invention provides an oil supply device, in which a path extending from an oil pump to an oil control valve is simplified in structure, thus allowing oil to flow smoothly and considerably reducing the occurrence of foreign matter. 
     Further, the present invention provides an oil supply device, in which oil can be supplied directly to an oil control valve through a cam shaft and a continuous variable valve timing unit without a separate path, thus reducing the length of a path and increasing the operating speed of the CVVT. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.