JP6441565B2 - Continuously variable transmission for vehicle - Google Patents

Description

  The present invention relates to a continuously variable transmission for a vehicle including input side and output side pulleys and a transmission belt.

  A belt type continuously variable transmission is well known as a continuously variable transmission for a vehicle. For example, it is a continuously variable transmission described in Patent Document 1. Patent Document 1 describes that hydraulic pressure is supplied to a continuously variable transmission and a starting clutch based on hydraulic pressure generated by a mechanical oil pump that is rotationally driven by an engine. In addition, Patent Document 1 discloses that when a predetermined engine stop condition is satisfied during vehicle deceleration, the clutch transmission torque transmitted to the primary pulley is the transmission torque of the continuously variable transmission (particularly, the transmission of the primary pulley). In order to prevent the torque from exceeding (torque), the hydraulic pressure supplied to the primary pulley is maintained to prevent a rapid drop, and the actual clutch pressure of the starting clutch is forcibly (rapidly) lowered, so that when the idle stop enters during deceleration ( That is, it is disclosed to prevent or suppress the occurrence of belt slip when the hydraulic pressure generated by the mechanical oil pump is reduced when the engine is stopped.

JP 2012-241746 A

  By the way, when the engine is idling stop during deceleration traveling, there is a possibility that a rapid deceleration operation by the driver is performed. In such a sudden deceleration operation, the more rapid the deceleration operation or the lower the road surface, the steeper the wheel braking (decrease in rotation), and the larger inertia torque due to the rotating inertial body is input to the continuously variable transmission. It becomes easy to be done. On the other hand, an electric oil pump is provided as an alternative to the mechanical oil pump, and when the engine is idling stopped during deceleration, the hydraulic pressure is applied to the continuously variable transmission or the like based on the oil pressure generated by the electric oil pump. Can be considered. However, when an electric oil pump is temporarily used as an alternative to the mechanical oil pump, a small electric oil pump having a smaller discharge flow rate than the mechanical oil pump is provided in consideration of arrangement space and cost. It will be. Therefore, depending on the size of the inertia torque that is input, the torque capacity of the continuously variable transmission (belt) due to the residual pressure of the continuously variable transmission or the hydraulic pressure supplied to the continuously variable transmission based on the hydraulic pressure generated by the electric oil pump. The inertia torque exceeds the clamping pressure), and belt slipping may occur. The above-described problem is not known.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is for a vehicle that can prevent belt slip even when the hydraulic pressure supplied to the pulley is low. The object is to provide a continuously variable transmission.

  The gist of the first invention for achieving the above object is as follows: (a) a fixed sheave, a movable sheave, and a hydraulic actuator that applies a thrust for changing a groove width between the fixed and movable sheave. A vehicular continuously variable transmission comprising input and output pulleys each having a transmission belt wound between the input and output pulleys, and (b) the hydraulic actuator includes: As the hydraulic pressure for imparting thrust, the hydraulic pressure discharged from a mechanical oil pump that is rotationally driven by the engine is used as the base pressure, and the discharge flow rate is lower than the discharge flow rate of the mechanical oil pump. A first oil chamber that can selectively receive one of the hydraulic pressures that is the hydraulic pressure discharged from the oil pump, and (c) the hydraulic pressure for applying the thrust In that a second oil chamber that can accept only hydraulic pressure to original pressure hydraulic said electric oil pump is discharged.

  In this case, the hydraulic pressure discharged from the electric oil pump is supplied to the oil chambers of the first oil chamber and the second oil chamber, so that the thrust is applied. Even if the hydraulic oil pressure is low, the hydraulic pressure discharged from the electric oil pump is the original hydraulic pressure, the oil pressure is applied to the pulley with a large pressure receiving area to obtain a large belt clamping pressure. Can do. Therefore, in the continuously variable transmission for a vehicle according to the present invention, it is possible to prevent belt slippage due to a decrease in belt clamping pressure even when the hydraulic pressure supplied to the pulley is low.

  The second aspect of the present invention is the vehicle continuously variable transmission according to the first aspect of the present invention, wherein the hydraulic pressure discharged from the electric oil pump when the engine is stopped is a working hydraulic pressure that is the first pressure. The oil chamber is supplied to both the oil chamber and the second oil chamber. In this way, even if the engine is stopped and the discharge flow rate of the mechanical oil pump is reduced to substantially zero, a large belt clamping pressure can be obtained by the operating hydraulic pressure using the hydraulic pressure discharged by the electric oil pump as a source pressure. Can be obtained. Note that if the electric oil pump is driven while the hydraulic oil remains in the first oil chamber even when the engine is stopped, the electric oil pump of the first oil chamber is exclusively used even when the electric oil pump outputs hydraulic pressure. A pressure receiving area can be secured.

1 is a diagram illustrating a schematic configuration of a vehicle and a block diagram illustrating a main part of a control system provided in the vehicle. FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining schematic structure of the continuously variable transmission for vehicles to which this invention is applied, and is a figure explaining the principal part regarding the hydraulic supply to the continuously variable transmission for vehicles.

  In the present invention, preferably, the hydraulic control circuit is configured to independently control, for example, the operating hydraulic pressure (pulley pressure) supplied to the hydraulic actuator. Alternatively, for example, the hydraulic control circuit is configured so as to generate pulley pressure as a result of controlling the flow rate of hydraulic oil to the hydraulic actuator. By such a hydraulic control circuit, the thrust in the pulley on the input side and the output side is controlled directly or indirectly (as a result), thereby preventing the transmission belt from slipping. Shift control is executed so that the following shift is realized. In this specification, “supplying hydraulic pressure” means “applying hydraulic pressure” or “supplying hydraulic oil controlled to the hydraulic pressure”.

  Preferably, the power of the engine is transmitted to the drive wheels via the vehicle continuously variable transmission. The engine is, for example, a gasoline engine such as an internal combustion engine, a diesel engine, or the like, but an electric motor or the like can also be employed as a driving force source in combination with the engine.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of the vehicle 10 and a block diagram illustrating a main part of a control system provided for controlling each part of the vehicle 10. In FIG. 1, in a vehicle 10, power output from an engine 12 as a driving power source for driving is a torque converter 14 as a fluid transmission device, a forward / reverse switching device 16, and a continuously variable for a vehicle to which the present invention is applied. The transmission is transmitted to the left and right drive wheels 24 sequentially through a belt-type continuously variable transmission 18 (hereinafter referred to as a continuously variable transmission 18), a reduction gear device 20, a differential gear device 22, and the like as a transmission.

  The torque converter 14 includes a pump impeller 14p connected to the engine 12 and a turbine impeller 14t connected to the forward / reverse switching device 16 via a turbine shaft 26, and transmits power through a fluid. A mechanical oil pump 28 is connected to the pump impeller 14p.

  The forward / reverse switching device 16 is mainly configured by a forward clutch C1, a reverse brake B1, and a double pinion planetary gear device 16p. The turbine shaft 26 of the torque converter 14 is integrally connected to the sun gear 16s of the planetary gear device 16p, and the input shaft 30 of the continuously variable transmission 18 is integrally connected to the carrier 16c of the planetary gear device 16p. The carrier 16c and the sun gear 16s are selectively connected via a forward clutch C1, and the ring gear 16r of the planetary gear unit 16p is selectively fixed to a housing 32 as a non-rotating member via a reverse brake B1. The The forward clutch C1 and the reverse brake B1 are known hydraulic friction engagement devices.

  In the forward / reverse switching device 16 configured as described above, when the forward clutch C1 is engaged and the reverse brake B1 is released, the turbine shaft 26 is directly connected to the input shaft 30, and the forward power transmission path is Established (achieved). When the reverse brake B1 is engaged and the forward clutch C1 is released, the forward / reverse switching device 16 establishes the reverse power transmission path, and the input shaft 30 is reverse to the turbine shaft 26. Rotated in the direction. When both the forward clutch C1 and the reverse brake B1 are released, the forward / reverse switching device 16 is set to a neutral state (power transmission cut-off state) in which power transmission is cut off.

  The continuously variable transmission 18 is an input side member provided on the input shaft 30 and an effective output side member provided on the input side pulley (primary pulley, primary sheave) 34 having a variable effective diameter and the output shaft 36. An output-side pulley (secondary pulley, secondary sheave) 38 having a variable diameter and a transmission belt 40 wound between the input-side and output-side pulleys 34, 38 are provided, and the input-side and output-side pulleys are provided. Power is transmitted through a frictional force between the pulleys 34 and 38 and the transmission belt 40.

  The primary pulley 34 is a fixed sheave 34a as an input-side fixed rotating body fixed to the input shaft 30, and an input-side movable rotation provided so as not to rotate relative to the input shaft 30 and to move in the axial direction. The input side thrust (primary thrust) Win (= primary pressure Pin × pressure receiving area) in the primary pulley 34 for changing the movable sheave 34b as a body and the V groove width between the fixed and movable sheaves 34a and 34b. An input-side hydraulic actuator (hydraulic cylinder) 34c is provided. The secondary pulley 38 has a fixed sheave 38a as an output side fixed rotating body fixed to the output shaft 36, and an output side provided so as not to be rotatable relative to the output shaft 36 and movable in the axial direction. An output side thrust (secondary thrust) Wout (= secondary pressure Pout × pressure-receiving area) in the secondary pulley 38 for changing the width of the V-groove between the movable sheave 38b and the fixed and movable sheaves 38a and 38b. ) And an output side hydraulic actuator 38c.

  Then, a primary pressure Pin, which is a working hydraulic pressure supplied to the input-side hydraulic actuator 34c, and a secondary pressure Pout, which is a working hydraulic pressure supplied to the output-side hydraulic actuator 38c, are respectively adjusted by a hydraulic control circuit 72 (see FIG. 2). By controlling the pressure, the primary thrust Win and the secondary thrust Wout are controlled. As a result, the V-groove widths of the pulleys 34 and 38 on the input side and the output side are changed to change the engagement diameter (effective diameter) of the transmission belt 40, and the transmission ratio (gear ratio) γ (= input shaft rotational speed Nin / The output shaft rotational speed Nout) is continuously changed, and the frictional force (belt clamping pressure) between the input side and output side pulleys 34 and 38 and the transmission belt 40 so that the transmission belt 40 does not slip. Is controlled. In this way, by controlling the primary thrust Win and the secondary thrust Wout, the actual speed ratio γ is set to the target speed ratio γtgt while preventing the transmission belt 40 from slipping.

  Further, the vehicle 10 is provided with an electronic control device 50 including a control device for the continuously variable transmission 18, for example. The electronic control unit 50 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM and follows a program stored in the ROM in advance. Various controls of the vehicle 10 are executed by performing signal processing. For example, the electronic control unit 50 is configured to execute output control of the engine 12, shift control of the continuously variable transmission 18, belt clamping pressure control, and the like, and for engine control, the continuously variable transmission 18 as necessary. It is configured separately for hydraulic control. The electronic control unit 50 also has various input signals (based on detection values detected by various sensors (for example, rotational speed sensors 52, 54, 56, 58, accelerator opening sensor 60) provided on the vehicle 10). For example, an engine rotation speed Ne, a turbine rotation speed Nt, an input shaft rotation speed Nin, an output shaft rotation speed Nout corresponding to the vehicle speed V, an accelerator opening degree θacc, and the like are supplied. Further, the electronic control device 50 outputs various output signals (for example, an engine output control command signal Se for controlling the output of the engine 12) to each device (for example, the engine 12, the hydraulic control circuit 72, etc.) provided in the vehicle 10. A hydraulic control command signal Scvt for hydraulic control related to the shift of the step transmission 18 is supplied.

  FIG. 2 is a diagram illustrating a schematic configuration of the continuously variable transmission 18 to which the present invention is applied, and also illustrates a main part related to the hydraulic supply to the continuously variable transmission 18 in the hydraulic system 70 provided in the vehicle 10. It is a figure explaining.

  In FIG. 2, the hydraulic system 70 includes a mechanical oil pump 28 and an electric oil pump 74 in addition to the hydraulic control circuit 72. The mechanical oil pump 28 is mechanically connected to the engine 12, and is rotationally driven by the engine 12 to control the speed change of the continuously variable transmission 18 or to reduce the belt clamping pressure in the continuously variable transmission 18. Generates (discharges) a hydraulic pressure that is a source pressure of the working hydraulic pressure for generating, switching the power transmission path in the forward / reverse switching device 16, and supplying lubricating oil to each part of the power transmission path of the vehicle 10. . The electric oil pump 74 is driven to rotate by the electric motor 76, thereby generating a hydraulic pressure that is the original pressure of the operating hydraulic pressure regardless of the rotational state of the engine 12 (for example, when the engine 12 stops rotating) (discharge). can do. For example, when the engine 12 is automatically stopped in the well-known automatic stop / restart control (eco-run control) of the engine 12, the mechanical oil pump 28 cannot discharge hydraulic oil. For this reason, the electric oil pump 74 is operated at the time of automatic engine stop in the eco-run control which is executed, for example, while the vehicle 10 is decelerating or stopped. As described above, the electric oil pump 74 is exclusively used temporarily as an alternative to the mechanical oil pump 28. For example, the rated maximum discharge flow rate is smaller than the discharge flow rate of the mechanical oil pump. Thus, downsizing is achieved. When the eco-run control as described above is executed during deceleration, the gear ratio γ is controlled toward the maximum gear ratio γmax (lowest gear ratio), so that, for example, the hydraulic pressure is released on the primary pulley 34 side and the V groove width The hydraulic pressure is supplied on the secondary pulley 38 side so as to obtain a predetermined belt clamping pressure. Therefore, it is considered that the oil pressure tends to be insufficient on the secondary pulley 38 side. Therefore, a schematic configuration of the continuously variable transmission 18 to which the present invention is applied will be described in an embodiment applied to the secondary pulley 38.

  The mechanical oil pump 28 and the electric oil pump 74 suck up the working oil returned to the oil pan 78 provided in the lower part of the housing 32 (transmission case) from a common suction port (strainer) 80, and discharge oil. Discharge to the paths 82 and 84. A discharge oil passage 82 of the mechanical oil pump 28 is connected to a first supply oil passage 88 via a first hydraulic control unit 86 in the hydraulic control circuit 72, and a discharge oil passage 84 of the electric oil pump 74 is hydraulic. The second hydraulic oil control unit 90 in the control circuit 72 is connected to the second supply oil path 92. Both the first hydraulic control unit 86 and the second hydraulic control unit 90 include, for example, a regulator valve that regulates the line hydraulic pressure, a control valve that regulates the secondary pressure Pout, and the like. Therefore, both the first hydraulic control unit 86 and the second hydraulic control unit 90 can supply the operating hydraulic pressure to the hydraulic actuator 38c using the hydraulic pressure discharged from the oil pumps 28 and 74 as a source pressure. Between the first supply oil path 88 and the second supply oil path 92, the hydraulic pressure output from the first hydraulic pressure control unit 86 (the hydraulic oil flowing through the first supply oil path 88) is the second supply oil path. A check valve 94 is provided to prevent inflow to the 92 side.

  The hydraulic actuator 38 c includes a first oil chamber 96 and a second oil chamber 98. The first oil chamber 96 is provided along the axial direction on the first cylinder 100 fixed on the output shaft 36 and on the support portion 100a that protrudes radially outward provided in the opening of the first cylinder 100. The intermediate cylinder 102 is larger than the first cylinder 100 and slides, and is fixed to the movable sheave 38b. The second oil chamber 98 includes a first cylinder 100, a second cylinder 104 having a larger diameter than the intermediate cylinder 102 and fixed on the output shaft 36, the outer peripheral surface of the first cylinder 100, and the first cylinder 100. The two cylinders 104 are formed by a piston 106 which is slid along the inner peripheral surface of the cylinder 104 along the axial direction and fixed at the end opposite to the movable sheave 38b of the intermediate cylinder 102.

  The first oil chamber 96 configured in this manner is communicated with a first oil passage 108 provided in the output shaft 36. The first oil passage 108 is communicated with the first supply oil passage 88 and the second supply oil passage 92. Therefore, the first oil chamber 96 has, as the working oil pressure Pout for applying the thrust Wout, the working oil pressure Pout1 using the oil pressure discharged from the mechanical oil pump 28 as a source pressure and the oil pressure discharged from the electric oil pump 74. One of the operating oil pressures Pout2 as the original pressure can be selectively received. The second oil chamber 98 is communicated with a second oil passage 110 provided in the output shaft 36. The second oil passage 110 is communicated with the second supply oil passage 92. Accordingly, the second oil chamber 98 can accept only the hydraulic pressure Pout2 having the hydraulic pressure discharged from the electric oil pump 74 as a source pressure as the hydraulic pressure Pout for applying the thrust Wout.

  In the hydraulic actuator 38c configured in this way, the operating hydraulic pressure Pout2 having the original pressure as the hydraulic pressure discharged from the electric oil pump 74 is supplied to both the first oil chamber 96 and the second oil chamber 98. . Therefore, compared to the case where the hydraulic pressure Pout2 is supplied only to the first oil chamber 96, the hydraulic pressure Pout2 is applied to the movable sheave 38b with a large pressure receiving area, and a large thrust Wout can be applied.

  Here, the electronic control unit 50 uses, for example, the hydraulic oil pressure Pout2 whose hydraulic pressure is discharged from the electric oil pump 74 when the engine 12 is stopped as an oil pressure in both the first oil chamber 96 and the second oil chamber 98. To supply. Specifically, the electronic control device 50 travels at a low vehicle speed, for example, when the vehicle 10 is temporarily stopped at an intersection or the like, separately from the start / stop of the engine 12 by a user operation such as an ignition key or an ignition switch. (For example, when the vehicle is decelerating), the engine 12 is automatically paused regardless of the user's operation to improve fuel efficiency, reduce exhaust gas, reduce noise, and the like. An automatic stop / restart control (eco-run control, idling stop control) of the engine 12 that automatically restarts is executed. For example, when a predetermined engine stop condition (idling stop start condition) is established, the electronic control unit 50 performs fuel cut control (and / or neutral control for releasing both the forward clutch C1 and the reverse brake B1). The engine 12 is temporarily stopped automatically. At this time, the electronic control unit 50 drives the electric motor 76 in order to rotate the electric oil pump 74 and output the hydraulic pressure. Thus, when the engine 12 is stopped, the operating oil pressure Pout2 based on the electric oil pump 74 is supplied to the first and second oil chambers 96, 98. In this way, even if the engine 12 is stopped and the discharge flow rate of the mechanical oil pump 28 is reduced or substantially zero, a larger thrust is generated by the operating hydraulic pressure Pout2 using the hydraulic pressure discharged by the electric oil pump 74 as a source pressure. Wout is applied and a large belt clamping pressure can be obtained. At this time, if the electric oil pump 74 is driven while the hydraulic oil remains in the first oil chamber 96 even if the engine 12 is stopped, even when the electric oil pump 74 outputs hydraulic pressure exclusively, The pressure receiving area of the first oil chamber 96 can be ensured. The predetermined engine stop condition is, for example, that the shift position is any one of “P”, “N”, and “D” positions, and that the accelerator opening degree Acc is determined to be zero, and that the vehicle speed is The vehicle condition is such that V is determined to be zero (or the vehicle speed V is determined to be equal to or lower than a predetermined eco-run permission vehicle speed). Further, when the shift position is the “D” position, a condition that the wheel brake is on (brake on) is added as a predetermined engine stop condition.

  As described above, according to the present embodiment, the operating oil pressure Pout2 having the oil pressure discharged from the electric oil pump 74 as a source pressure is supplied to the first and second oil chambers 96 and 98, and thus the thrust Wout is applied. Even if the hydraulic pressure for the operation is a low hydraulic pressure that is exclusively the hydraulic pressure discharged from the electric oil pump 74, the hydraulic pressure is applied to the pulley 38 with a large pressure receiving area, and a large belt A pinching pressure can be obtained. Therefore, the continuously variable transmission 18 can prevent belt slippage due to a decrease in belt clamping pressure even when the hydraulic pressure supplied to the pulley 38 is low. Moreover, the enlargement of the electric oil pump 74 can be suppressed.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, the continuously variable transmission 18 to which the present invention is applied is transmitted to the vehicle 10 that transmits the power of the engine 12 to the drive wheels 24 sequentially via the torque converter 14, the forward / reverse switching device 16, the continuously variable transmission 18, and the like. Although provided, it is not limited to this. For example, instead of the torque converter 14, another fluid transmission device such as a fluid coupling (fluid coupling) having no torque amplification function may be used. Further, when the forward / reverse switching device 16 functions as the starting mechanism, is provided with a starting mechanism such as a starting clutch, or is provided with an engaging device or the like capable of connecting / disconnecting a power transmission path, the fluid transmission The device may not be provided.

  In the above-described embodiment, the check valve 94 is provided, so that the first oil chamber 96 operates as one of the operating oil pressure Pout1 and the operating oil pressure Pout2 as the operating oil pressure Pout for applying the thrust Wout. Although the hydraulic pressure is selectively received, the present invention is not limited to this mode. For example, instead of the check valve 94, for example, a switching valve for switching between communication and blocking of the oil passage is provided, and the communication of the oil passage is switched by the on / off solenoid valve in accordance with the drive of the electric oil pump 74. It may be a mode.

  In the above-described embodiment, the case where the engine 12 is automatically stopped in the eco-run control is exemplified as the case where the electric oil pump 74 is driven. However, the present invention is not limited to this. For example, the electric oil pump 74 may be driven during the operation of the engine 12. In such a case, as the operating oil pressure for applying the thrust Wout, in addition to the operating oil pressure Pout1 using the oil pressure discharged from the mechanical oil pump 28 as the original pressure, the oil pressure discharged from the electric oil pump 74 is used as the original pressure. The working hydraulic pressure Pout2 is supplied to the hydraulic actuator 38c.

  In the above-described embodiment, the embodiment in which the present invention is applied to the secondary pulley 38 is illustrated, but the present invention is not limited to this. For example, the present invention may be applied to the primary pulley 34 in addition to or instead of the secondary pulley 38. That is, the primary pulley 34 includes a first oil chamber 96 and a second oil chamber 98, and the first oil chamber 96 has a hydraulic pressure discharged from the mechanical oil pump 28 as an operating hydraulic pressure Pin for applying a thrust Win. One of the working oil pressure Pin1 that is the original pressure and the working oil pressure Pin2 that is the oil pressure discharged from the electric oil pump 74 may be selectively received.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

12: Engine 18: Belt type continuously variable transmission (vehicle continuously variable transmission)
28: mechanical oil pumps 34, 38: input and output pulleys 34a, 38a: fixed sheaves 34b, 38b: movable sheaves 34c, 38c: hydraulic actuator 40: transmission belt 74: electric oil pump 96: first oil Chamber 98: Second oil chamber

Claims (1)

Between the input side and output side pulleys each having a fixed sheave, a movable sheave, and a hydraulic actuator that applies thrust to change the groove width between the fixed and movable sheaves, and between the input side and output side pulleys A continuously variable transmission for a vehicle comprising a transmission belt wound around
The hydraulic actuator is
The operating oil pressure for applying the thrust was an operating oil pressure based on the oil pressure discharged from a mechanical oil pump that is driven to rotate by the engine, and a discharge flow rate smaller than the discharge flow rate of the mechanical oil pump. A first oil chamber capable of selectively receiving one of the hydraulic oil pressures whose original pressure is the hydraulic pressure discharged from the electric oil pump;
And a second oil chamber capable of receiving only the hydraulic pressure having the hydraulic pressure discharged from the electric oil pump as a primary pressure as the hydraulic pressure for applying the thrust. Step transmission.

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