Abstract:
The present invention provides a hydraulic control system of a power train for a hybrid vehicle that allows the power train of a hybrid vehicle to implement all of two or more EV modes, two or more power split modes, and at least three or more fixed-stage modes, with a relatively simple configuration, and achieves satisfactory power performance of the power train and fuel efficiency and reduce the cost of the valve body, remove possibility of malfunction, and implements a limp home function when a controller is broken.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Korean Patent Application Number 10-2009-0119717 filed Dec. 4, 2009, the entire contents of which application is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a hydraulic control system of a power train for a hybrid vehicle, in more detail, a hydraulic control technology for controlling a power train of a hybrid vehicle which can implement two or more power split modes and three or more fixed-stage modes. 
     2. Description of Related Art 
       FIG. 1  illustrates the configuration of a power train of a hybrid vehicle using the present invention, which includes an engine Engine, a first motor generator MG 1 , and a second motor generator MG 2 . Further, a first planetary gear set PG 1  and a second planetary gear set PG 2  are provided to receive from the engine and the motor generators, such that the output for the driving wheels comes from the second planetary gear set. 
     The planetary gear set is a singe pinion planetary gear set including a first sun gear S 1 , a first carrier C 1 , and first ring gear R 1  and the second planetary gear set is a single pinion planetary gear set including a second sun gear S 2 , a second carrier C 2 , and a second ring gear R 2 , in which the second carrier is directly connected with the first ring gear and connected to the driving wheels through an output member Output. 
     Total four operating members are connected to the rotary members of the first planetary gear set and the second planetary gear set to restrict rotation of the rotary members, such that it is possible to implement various driving modes with the engine, the first motor generator, and the second motor generator, as shown in  FIG. 2 . 
     That is, a first brake BK 1  is connected to first sun gear S 1 , a second brake BK 2  is connected to second ring gear R 2 , a first clutch CL 1  is connected between first carrier C 1  and second ring gear R 2 , a second clutch CL 2  is connected between first carrier C 1  and second sun gear S 2 , engine Engine is connected to first carrier C 1 , first motor generator MG 1  is connected to first sun gear S 1 , second motor generator MG 2  is connected to second sun gear S 2 , such that it is possible to implement various driving modes, in accordance with the operational states of first brake BK 1 , second brake BK 2 , first clutch CL 1 , and second clutch CL 2 , which are the operating members, the engine, and the first motor generator and the second motor generator. 
     The information disclosed in this Background of the Invention 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 OF THE INVENTION 
     Various aspects of the present invention are directed to provide a hydraulic control system of a power train for a hybrid vehicle that allows the power train of a hybrid vehicle to implement all of a plurality of EV modes, a plurality of power split modes, and a plurality of fixed-stage modes, with a relatively simple configuration, and achieves satisfactory power performance of the power train and fuel efficiency and reduce the cost of the valve body. 
     An aspect of the present invention provides a hydraulic control system of a power train for a hybrid vehicle, which includes a line pressure and lubrication pressure generating unit that generates predetermined line pressure and lubrication pressure for lubrication, using hydraulic pressure supplied from an oil pump, a first reducing valve that generates first reducing pressure by decreasing the line pressure, a second reducing valve that generates second reducing pressure by decreasing the line pressure, a first clutch control unit that receives the line pressure, the first reducing pressure, and the second reducing pressure and controls a first clutch, a second clutch control unit that receives the line pressure, the first reducing pressure, and the second reducing pressure and controls a second clutch, a first brake control unit that receives the line pressure, the first reducing pressure, and the second reducing pressure and controls a first brake, a second brake control unit that receives the line pressure, the first reducing pressure, and the second reducing pressure and controls a second brake, and a manual valve MV that receives the line pressure, and supplies the line pressure to the first brake control unit, the second brake control unit, and the first clutch control unit in a D-stage state, and supplies the line pressure to the second brake-control unit in the R-stage state. 
     Another aspect of the present invention provides a hydraulic control system of a power train for a hybrid vehicle, which includes a line pressure and lubrication pressure generating unit that generates predetermined line pressure and lubrication pressure for lubrication, using hydraulic pressure supplied from an oil pump, a first reducing valve and a second reducing valve that generate first reducing pressure and second reducing pressure by decreasing the line pressure, a first clutch control unit, a second clutch control unit, a first brake control unit, and a second brake control unit that receive the line pressure, the first reducing pressure, and the second reducing pressure and respectively control a first clutch, a second clutch, a first brake, and a second brake, which are operating members to control, a manual valve and a D-R check valve that receive the line pressure, supply the line pressure to the first brake control unit, the second brake control unit, and the first clutch control unit in a D-stage state, and supply the line pressure to the second brake-control unit and the first clutch control unit in an R-stage state, an R-stage fail-safe valve that stops the line pressure and the lien pressure directly supplied from the lubrication pressure generating unit to the second clutch control unit in the R-stage state, a second brake fail-safe valve that removes the hydraulic pressure of the second brake when operation pressure is supplied to both the first clutch and the second clutch, and a first brake fail-safe valve that removes the hydraulic pressure of the first brake when operation pressure is supplied to any one of the second brake and the second clutch. 
     The present invention allows the power train of a hybrid vehicle to implement all of two or more EV modes, two or more power split modes, and at least three or more fixed-stage modes, with a relatively simple configuration, and achieves satisfactory power performance of the power train and fuel efficiency and reduce the cost of the valve body, remove possibility of malfunction, and implements a limp home function when a controller is broken. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a power train of a hybrid vehicle using the present invention. 
         FIG. 2  is a table showing drive modes implemented by the power train shown in  FIG. 1 . 
         FIG. 3  is a diagram illustrating the configuration of an exemplary hydraulic control system of a power train for a hybrid vehicle according to the present invention. 
         FIG. 4  is a view showing in detail the manual valve shown in  FIG. 3 . 
         FIG. 5  is a view showing in detail the D-R check valve shown in  FIG. 3 . 
         FIG. 6  is a view showing in detail the R-N-D static control unit shown in  FIG. 3 . 
         FIG. 7  is a view showing in detail the first clutch control unit shown in  FIG. 3 . 
         FIG. 8  is a view showing in detail the second brake fail-safe valve shown in  FIG. 3 . 
         FIG. 9  is a view showing in detail the first brake fail-safe valve shown in  FIG. 3 . 
         FIG. 10  is a view showing in detail the R-stage fail-safe valve shown in  FIG. 3 . 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION OF THE INVENTION 
     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. 
     Referring to  FIG. 3 , an exemplary embodiment of the present invention includes a line pressure and lubrication pressure generating unit RL-CON that generates predetermined line pressure and lubrication pressure for lubrication, using hydraulic pressure supplied from an oil pump, a first reducing valve RED 1  and a second reducing valve RED 2  that generate first reducing pressure and second reducing pressure respectively by decreasing the line pressure, a first clutch control unit CL 1 -CON, a second clutch control unit CL 2 -CON, a first brake control unit BK 1 -CON, and a second brake control unit BK 2 -CON that receive the line pressure, the first reducing pressure, and the second reducing pressure and respectively control a first clutch CL 1 , a second clutch CL 2 , a first brake BK 1 , and a second brake BK 2 , which are operating members to control, a manual valve MV and a D-R check valve D-R-CV that receive the line pressure, supply the line pressure to first brake control unit BK 1 -CON, the second brake control unit BK 2 -CON, and first clutch control unit CL 1 -CON in the D-stage state, and supply the line pressure to second brake-control unit BK 2 -CON and first clutch control unit CL 1 -CON in the R-stage state, an R-stage fail-safe valve R-FSV that stops the line pressure and the lien pressure directly supplied from lubrication pressure generating unit RL-CON to second clutch control unit CL 2 -CON in the R-stage state, a second brake fail-safe valve BK 2 -FSV that removes the hydraulic pressure of second brake BK 2  when operation pressure is supplied to both first clutch CL 1  and second clutch CL 2 , and a first brake fail-safe valve BK 1 -FSV that removes the hydraulic pressure of first brake BK 1  when operation pressure is supplied to any one of second brake BK 2  and second clutch CL 2 . 
     First clutch CL 1 , second clutch CL 2 , first brake BK 1 , and second brake BK 2  are, as shown in  FIG. 1 , included in the power train of a hybrid vehicle that includes, a first planetary gear set PG 1  including a first sun gear S 1 , a first carrier C 1 , and a first ring gear R 1 , a second planetary gear set PG 2  including a second carrier C 2  directly connected to first ring gear R 1 , a second sun gear S 2 , and a second ring gear R 2 , a first motor generator MG 1  connected to first sun gear S 1  of first planetary gear set PG 1 , a second motor generator MG 2  connected to second sun gear S 2  of second planetary gear set PG 2 , an engine Engine connected to first carrier C 1  of first planetary gear set PG 1 , and an output member Output connected to second carrier C 2  of second planetary gear set PG 2 . 
     First clutch CL 1  is disposed to connect/disconnect first carrier C 1  and second ring gear R 2 , second clutch CL 2  is disposed to connect/disconnect first carrier C 1  and second sun gear S 2 , first brake BK 1  is disposed to restrict rotation of first sun gear S 1 , and second brake BK 2  is disposed to restrict rotation of second ring gear R 2 . 
     Line pressure and lubrication pressure generator RL-CON includes, a variable force solenoid valve VFS that receives second reducing pressure from second reducing valve RED 2  and generates solenoid control pressure, a regulator valve REGV that is controlled by the solenoid control pressure from variable force solenoid valve VFS and generates the line pressure, using the hydraulic pressure supplied from the oil pump, and a lubrication pressure regulator valve LRV that is controlled by the solenoid control pressure from variable solenoid valve VFS and generates the lubrication pressure, using the hydraulic pressure from regulator valve REGV. 
     Manual valve MV, as shown in detain in  FIG. 4 , includes a line pressure port MV-L that receives line pressure from line pressure and lubrication pressure generating unit RL-CON, a D-stage port MV-D that supplies line pressure to first brake control unit BK 1 -CON, second brake control unit BK 2 -CON, and first clutch control unit CL 1 -CON, an R-stage port MV-R that supplies line pressure to second brake control unit BK 2 -CON and first clutch control unit CL 1 -CON, and a valve spool MV-SP that implements a P-stage and an N-stage at the same position where line pressure port MV-L is isolated, moves from the N-stage position to one side such that line pressure port MV-L communicates with D-stage port MV-D, and to the other side such that line pressure port MV-L communicates with R-stage port MV-R. 
     That is, the P-stage and the N-stage are set to the same position at the center, such that the D-stage state where line pressure port MV-L communicates with only D-stage port MVD is implemented by moving valve spool MV-SP to the right side from the P-stage and N-stage and the R-stage state where line pressure port MV-L communicates with only R-stage port MV-R by moving valve spool MV-SP to the left side. 
     D-R check valve D-R-CV, as shown in  FIG. 5 , includes a first port D-R- 1  that is connected to D-stage port MV-D of manual valve MV, a second port D-R- 2  that is connected to R-stage port MV-R of manual valve MV, a third port D-R- 3  that is connected to first clutch control unit CL 1 -CON and second brake control unit BK 2 -CON, and a valve spool D-R-SP that slides straight such that first port D-R- 1  communicates with third port D-R- 3  when hydraulic pressure is supplied to first port D-R- 1  and second port D-R- 2  communicates with third port D-R- 3  when hydraulic pressure is supplied to second port D-R- 2 . 
     Therefore, D-R check valve D-R-CV operates with selection of the D-stage and the R-stage of manual valve MV, such that the line pressure from manual valve MV is supplied to first clutch control unit CL 1 -CON and second brake control unit BK 2 -CON through third port D-R- 3 , regardless of that manual valve MV is in the D-stage state or the R-stage state. 
     The present embodiment further includes an R-N-D static control unit R-N-D-CON between manual valve MV and second brake control unit BK 2 -CON to relatively rapidly supply the line pressure from manual valve MV to second brake control unit BK 2 -CON, and relatively slowly remove the hydraulic pressure from second brake control unit BK 2 -CON. 
     In the present embodiment, R-N-D static control unit R-N-D-CON is disposed between D-R check valve D-R-CV and second brake control unit BK 2 -CON, and R-N-D static control unit R-N-D-CON, as shown in  FIG. 6 , includes an RND check valve RND-CV that forms only a channel to second brake control unit BK 2 -CON from D-R check valve D-R-CV, an orifice RND-O that is formed in a channel detouring RND check valve RND-CV, and an accumulator RND-ACC that is disposed between orifice RND-O and second brake control unit BK 2 -CON. 
     R-N-D static control unit R-N-D-CON described above improves response by allowing line pressure to be rapidly supplied to second brake BK 2  through second brake control unit BK 2 -CON, when a driver moves the shift lever from the P-stage or the N-stage to the D-stage or the R-stage, and relatively slowly removes the hydraulic pressure of second brake BK 2  through second brake control unit BK 2 -CON to maintain a predetermined level of hydraulic pressure of second brake BK 2 , when the shift lever is moved from the D-stage or the R-stage to the N-stage and the P-stage, such that control performance is improved when the driver repeatedly and rapidly moves the shift lever between the N-stage, the R-stage, and the D-stage, for parking, and rapid response is ensured when a shift shock does not occur. 
     In this configuration, the reason that R-N-D static control unit R-N-D-CON controls the line pressure supplied to second brake BK 2 , as described, is that, as can be seen from  FIG. 2 , only second brake BK 2  is engaged in both the EV 1  mode and the rearward mode, which are used to start a vehicle, in a hybrid vehicle, and also that second brake BK 2  is the operating member that are used the most driving modes. 
     First brake control unit BK 1 -CON includes a normally-low type variable force solenoid valve VFS that generates solenoid control pressure using second reducing pressure received from second reducing valve RED 2 , a pressure control valve PCV that is integrally formed at one side of variable force solenoid valve VFS and outputs operation pressure of first brake BK 1 , using the line pressure, and a pressure switch valve PSW that is converted to feedback or stop a portion of operation pressure, supplied to first brake BK 1 , to pressure control valve PCV, using first reducing pressure received from first reducing valve RED 1  at one side and solenoid control pressure from variable force solenoid valve VFS from the other side. 
     Second brake control unit BK 2 -CON includes a normally-high type variable force solenoid valve VFS that generates solenoid control pressure using second reducing pressure received from second reducing valve RED 2  and, a pressure control valve PCV that is integrally formed at one side of variable force solenoid valve VFS and outputs operation pressure of second brake BK 2 , using the line pressure, a pressure switch valve PSW that is converted to feedback or stop a portion of operation pressure, supplied to second brake BK 2 , to pressure control valve PCV, using first reducing pressure received from first reducing valve RED 1  at one side and solenoid control pressure from variable force solenoid valve VFS from the other side. 
     First clutch control unit CL 1 -CON includes a normally-high type variable force solenoid valve VFS that generates solenoid control pressure using second reducing pressure received from second reducing valve RED 2  and, a pressure control valve PCV that is integrally formed at one side of variable force solenoid valve VFS and outputs operation pressure of first clutch CL 1 , using the line pressure, a pressure switch valve PSW that is converted to feedback or stop a portion of operation pressure, supplied to first clutch CL 1 , to pressure control valve PCV, using first reducing pressure received from first reducing valve RED 1  at one side and solenoid control pressure from variable force solenoid valve VFS from the other side. 
     Second clutch control unit CL 2 -CON includes a normally-high type variable force solenoid valve VFS that generates solenoid control pressure using second reducing pressure received from second reducing valve RED 2  and, a pressure control valve PCV that is integrally formed at one side of variable force solenoid valve VFS and outputs operation pressure of second clutch CL 2 , using the line pressure, a pressure switch valve PSW that is converted to feedback or stop a portion of operation pressure, supplied to second clutch CL 2 , to pressure control valve PCV, using first reducing pressure received from first reducing valve RED 1  at one side and solenoid control pressure from variable force solenoid valve VFS from the other side. 
     That is, first brake control unit BK 1 -CON, second brake control unit BK 2 -CON, first clutch control unit CL 1 -CON, and second clutch control unit CL 2 -CON all have substantially the same structure, and respectively includes variable force solenoid valve VFS that generates the solenoid control pressure, using the second reducing pressure from second reducing valve RED 2 , pressure control valve PCV that is integrally formed an one side of variable force solenoid valve VFS and outputs the operation pressure for one corresponding operating member to control in first brake BK 1 , second brake BK 2 , first clutch CL 1 , and second clutch CL 2 , using the line pressure received, and pressure switch valve PSW that is converted to feedback or stop a portion of the operation pressure supplied to the corresponding operating member to control to pressure control valve PCV, using the first reducing pressure received from first reducing valve RED 1  at one side of the valve spool and the solenoid control pressure received from variable force solenoid valve VFS from the other side. 
     Therefore, in the figures, variable force solenoid valve VFS, pressure control valve PCV, and pressure switch valve PSW are designated by the same reference numerals and  FIG. 7  representatively shows the structure of first clutch control unit CL 1 -CON in detail. 
     Second brake fail-safe valve BKS-FSV, as shown in detail in  FIG. 8 , includes a first port BK 2 - 1  that receives operation pressure supplied to first clutch CL 1 , in parallel with first clutch CL 1 , a second port BK 2 - 2  that receives operation pressure supplied to second clutch CL 2 , in parallel with second clutch CL 2 , a third port BK 2 - 3  and a fourth port BK 2 - 4  through which operation pressure supplied to second brake BK 2  from second brake control unit BK 2 -CON is transmitted inside and outside, respectively, a fifth port BK 2 - 5  that receives the line pressure, a valve spool BK 2 -SP that closes third port BK 2 - 3  and fourth port BK 2 - 4  and removes the pressure of second brake BK 2 , only when operation pressure is simultaneously applied to first port BK 2 - 1  and second port BK 2 - 2 , by making the operation pressure of first port BK 2 - 1  and second port BK 2 - 2  correspond to the line pressure of fifth port BK 2 - 5 . 
     Therefore, the hydraulic pressure of second brake BK 2  is structurally removed while the operation pressure is respectively supplied to first clutch CL 1  and second clutch CL 2 , which is because, referring to  FIG. 2 , a power train for a hybrid vehicle using the present invention do not have a mode for connecting first clutch CL 1  and second clutch CL 2  with second brake BK 2 . 
     Further, as described above, since first clutch control unit CL 1 -CON, second clutch control unit CL 2 -CON, and second brake control unit BK 2 -CON respectively includes normally-high type variable force solenoid valve VFS that increases the solenoid control pressure to the highest level, when they cannot be supplied with control current, the operation pressure can be supplied to first clutch CL 1 , second clutch CL 2 , and second brake BK 2 , when malfunction occurs in the electric device, in which when the operation pressure is supplied to both of first clutch CL 1  and second clutch CL 2 , second brake fail-safe valve BK 2 -FSV mechanically stops and remove the operation pressure for second brake BK 2  and generates that a 1,1 transmission gear ratio mode of two-stage fixed gear ratio, such that a limp home function can be implemented. 
     First brake fail-safe valve BK 1 -FSV, as shown in detail in  FIG. 9 , includes a first port BK 1 - 1  that receives operation pressure supplied to second brake BK 2 , in parallel with second brake BK 2 , a second port BK 1 - 2  that receives operation pressure supplied to second clutch CL 2 , in parallel with second clutch CL 2 , a third port BK 1 - 3  and a fourth port BK 1 - 4  through which operation pressure supplied from first brake control unit BK 1 -CON to first brake BK 1  is transmitted inside and outside, a fifth port BK 1 - 5  that receives line pressure through D-stage port MVD of manual valve MV, and a valve spool BK 1 -SP that closes third port BK 1 - 3  and fourth port BK 1 - 4  and removes the pressure of first brake BK 1 , when operation pressure is applied to any one of first port BK 1 - 1  and second port BK 1 - 2 , by making operation pressure of first port BK 1 - 1  and second port BK 1 - 2  to the line pressure of fifth port BK 1 - 5 . 
     Therefore, while operation pressure is supplied to any one of first brake BK 2  and second clutch CL 2 , first brake fail-safe valve BK 1 -FSV removes hydraulic pressure of first brake BK 1 , and this is for structurally prevent an unexpected operational state is formed by first brake fail-safe valve BK 1 -FSV in any case, because, referring to  FIG. 2 , first brake BK 1  is not connected with any member other than first clutch CL 1  at a third fixed-stage mode. 
     R-stage fail-safe valve R-FSV, as shown in detail in  FIG. 10 , includes a first port R- 1  that is connected with an R-stage port MV-R of manual valve MV, a second port R- 2  and a third port R- 3  through which the line pressure supplied from line pressure and lubrication pressure generating unit RL-CON to second clutch control unit CL 2 -CON are transmitted inside and outside, respectively, a valve spool R-SP that closes second port R- 2  and third port R- 3 , when hydraulic pressure is applied to first port R- 1  from R-stage port MV-R, and a bias spring R-S that makes valve spool R-SP elastically support second port R- 2  and third port R- 3  to be opened. 
     In the present embodiment, R-stage fail-sage valve R-FSV further includes a fourth port R- 4  providing hydraulic pressure pressing valve spool R-SP together with bias spring R-S and fourth port R- 4  is connected with first reducing valve RED 1  to receive the first reducing pressure. 
     Although valve spool R-SP can make second port R- 2  and third port R- 3  connected with each other, only with bias spring R-S, unless R-stage operation pressure is applied to first port R- 1 , in order to ensure more stable operability, it has fourth port R- 4  such that the first reducing pressure supplements the elastic force of bias spring R-S. 
     The power train for a hybrid vehicle according to an exemplary embodiment of the present invention can generate electricity with second motor generator MG 2  by connecting only second clutch CL 2  for charging the battery, and driving engine Engine, in the P-stage or N-stage state, which is performed by a controller without a user. 
     In order to implement the states, by making second clutch control unit CL 2 -CON be directly supplied with the line pressure, which is supplied for the operation pressure of second clutch CL 2 , through not manual valve MV, but R-stage fail-safe valve R-FSV, when R-stage operation pressure is supplied to R-stage fail-safe valve R-FSV by selecting the R-stage in manual valve MV, the line pressure supplied to second clutch control unit CL 2 -CON is mechanically stopped, thereby preventing second clutch CL 2  from being mechanically connected. 
     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.