KR19990051108A - Continuously variable transmission - Google Patents

Abstract

The present invention relates to a continuously variable transmission for a vehicle that transmits a driving force of an engine to a transmission input shaft by using a torque converter and improves oscillation performance, while improving power transmission efficiency and improving fuel economy using two oil pumps. The continuously variable transmission includes a torque converter 12 which transmits the rotational force of the engine transmitted through the flywheel to the carrier 32 of the planetary gear set 30 via the turbine shaft 18, and rotates by the turbine shaft 18. The first oil pump 8 and the second oil pump 16 for supplying the oil in the oil tank and supplying the oil to the first hydraulic cylinder 54 and the second hydraulic cylinder 52 are provided. .

Description

Continuously variable transmission

The present invention relates to a continuously variable transmission for a vehicle, and more particularly, by using a torque converter to transmit the driving force of the engine to the transmission input shaft to improve oscillation performance, while using two oil pumps to increase power transmission efficiency and fuel economy. The present invention relates to a continuously variable transmission for a vehicle.

Currently, transmissions used in automobiles can be classified into manual transmissions, automatic transmissions, and continuously variable transmissions according to the transmission method.In addition to the function of converting the rotational force of the engine and transmitting it to the driving wheel, the engine idling when the vehicle is stopped It is possible to reverse the direction of rotation of the drive wheels.

In conventional manual transmissions or hydraulic automatic transmissions, since the transmission ratio is very limited according to the rotational speed of the engine, it is impossible to continuously and continuously change the gearbox. In a continuously variable transmission, the speed ratio can be selected almost independently of the engine speed. Therefore, in a vehicle equipped with a continuously variable transmission, it is possible to control the maximum output state or the lowest fuel consumption state within a short time in all driving regions of the engine.

In addition, since transmission of power is not interrupted even during shifting, there is almost no shift shock. As a continuously variable transmission for automobiles, a method of continuously changing speed is adopted by changing the effective diameter of a pulley using a rubber belt or a chain. Both the belt drive system and the chain drive system change the reduction ratio steplessly by changing the widths of both pulleys. The width of the pulleys is hydraulic, the low speed when the input side is wide, and the high speed when the input side is wide. Usually, the speed ratio is converted steplessly between 0.5 and 2.5.

1 is a block diagram showing a gear train for a continuously variable transmission of the belt drive method. The flywheel 2 is fixed to one end of the crankshaft, and the driving force of the engine transmitted through the flywheel 2 is transmitted to the driveshaft through the clutch 4. The clutch 4 is operatively coupled to the drive shaft 10 via the diaphragm 6, and optionally serves to transfer engine power to the continuously variable transmission. The drive shaft 10 is driven with an oil pump 8 for supplying oil to a hydraulic control device for controlling various frictional engagement elements.

The driving force of the engine input to the drive shaft 10 through the clutch 4 is transmitted to the planetary gear set 30 through the carrier 32. The planetary gear set 30 includes a sun gear 34 connected to the transmission input shaft 40, a double pinion 36 and 36 'external to the sun gear 34, and the double pinion 36 and 36'. It consists of a ring gear 38 in contact. The carrier 32 is operatively connected with the forward clutch 42, and the ring gear 38 is operatively connected with the reverse clutch 44.

One side of the forward clutch 42, which is engaged at the time of forward movement and inputs the driving force of the engine transmitted through the carrier 32 of the planetary gear set 30, is operatively connected to the transmission input shaft 40 via the connector 46. It is connected. One of the reversing clutches 44 engaged at the time of reversing and enabling reversal is fixed to the transmission housing 20.

The driving pulley 50 is splined to the other end of the input shaft 40 to which the sun gear 34 is fixed. The driving pulley 50 transmits the driving force input from the carrier 32 through the planetary gear set 30 and the input shaft 40 to the driven pulley 56 via the belt V. Power transmitted to the driven pulley 56 is transmitted to the idler shaft 64 through the driven shaft 58, the intermediate pinion 60 and the idler gear 62, and the driving force transmitted to the idler shaft 64 is the longitudinal deceleration. It is transmitted to the differential gear 70 via the pinions 36 and 36 'and the longitudinal reduction gear 68 and then to the left and right driving wheels, thereby enabling the vehicle to start.

In the continuously variable transmission of this configuration, when the shift lever is positioned at the parking P or the neutral N, both the forward clutch 42 and the reverse clutch 44 are kept in the released state. However, at the parking P position, the driven pulley 52 is mechanically fixed by the parking lock or the like.

When the driver selects the advance lever D, the speed limit, or the load operation L as the selection lever, the forward clutch 42 is engaged and the reverse clutch 44 is maintained in the released state. By engaging the forward clutch 42, the carrier 32 is directly connected to the input shaft 40 via the connector 46. That is, the rotational force of the engine transmitted through the drive shaft while the planetary gear set is integrally rotated is transmitted to the drive pulley 50 through the input shaft 40. The rotational force of the driving pulley 50 is transmitted to the driven pulley 56 via the belt V, and the power transmitted to the driven pulley 56 is in turn driven by the driven shaft 58, the intermediate pinion 60, and the idler. After the gear 62 and the idler shaft 64 are transferred to the longitudinal deceleration pinions 36 and 36 'and the longitudinal reduction gear 68, they are transmitted to the left and right driving wheels through the differential gear 70.

If the selection lever is located in the reverse direction R, the forward clutch 42 is released by the control of the hydraulic control device and the reverse clutch 44 is engaged by the hydraulic pressure. Accordingly, the reverse clutch 44 secures the ring gear 38 with respect to the transmission housing 20 to provide a reaction force. By fixing the ring gear 38, the pinion 36 engaged with the ring gear 38 is rotated in the opposite direction to the rotation direction of the carrier 32, and the pinion 36 'engaged with the sun gear 34 is It is rotated in the same direction as the rotation direction of the carrier 32. As a result, since the sun gear 34 is rotated in the opposite direction to the rotation direction of the carrier 32, the drive pulley 50 is rotated in the opposite direction to the rotation direction of the drive shaft 10.

In the conventional continuously variable transmission for a vehicle having such a configuration, since the driving force of the engine is directly transmitted to the carrier through the clutch 4, the oscillation process is not flexible, and the torque shock and rotational vibration of the engine are transmitted as it is, and the pump is applied. Since the capacity of is always constant, there is a problem that the power consumption is increased, thereby lowering the power transmission efficiency.

The present invention devised to solve such a problem provides a continuously variable transmission for a vehicle that enables a flexible starting and reduces the inflow of torque shock rotational vibration of the engine by transmitting the driving force of the engine to the input shaft using a torque converter. Its purpose is to.

Another object of the present invention is to provide a variety of valves for controlling the continuously variable transmission by forming two large and small hydraulic pressures using two oil pumps, thereby reducing the power consumption of the engine to improve fuel efficiency of the vehicle continuously variable transmission. The purpose is to provide a hydraulic control device.

1 is a block diagram showing a gear train of a continuously variable transmission for a vehicle according to the prior art,

2 is a block diagram showing a gear train of a continuously variable transmission for a vehicle according to the present invention;

3 is a circuit diagram showing a hydraulic control device of a continuously variable transmission for a vehicle according to the present invention.

♣ Explanation of symbols for main part of drawing ♣

8, 16: 1st, 2nd oil pump 12: Torque converter

14: Lockup clutch 18: Turbine shaft

20: Transmission housing 30: Planetary gear set

32: carrier 34: sun gear

36: Pinion 38: Ring gear

40: input shaft 42, 44: forward, reverse clutch

46: Connector 50, 52: Drive, driven pulley

54, 56: 1st, 2 hydraulic cylinders 58: driven shaft

60: middle pinion 62: children gear

64: children shaft 66: longitudinal reduction pinion

68: reduction gear 70: differential gear

80: TCU 82: Pump capacity selector valve

84: line pressure control valve 86: pulley pressure control valve

88: pulley pressure alternating valve 90: clutch pressure control valve

92: manual valve 94: reversing valve

96: Lockup pressure control valve 98: Lockup clutch valve

100: selection lever S1 to S5: first to fifth solenoids

An object of the present invention described above is a planetary gear set that is fixed to the transmission housing and the input shaft selectively according to the operation of the forward clutch and the reverse clutch, and transmits an engine driving force, and an engine fixed to one end of the input shaft and transmitted through the planetary gear set. Drive pulley rotated by driving force, driven pulley which interlocks with drive pulley through belt and transmits rotational force of input shaft through differential gear through driven shaft and idler shaft, and diameter ratio of driving pulley and driven pulley by hydraulic pressure. In a continuously variable transmission for a vehicle including a first hydraulic cylinder and a second hydraulic cylinder to be changed, a torque converter which transmits the rotational force of the engine transmitted through the flywheel to the carrier of the planetary gear set via the turbine shaft, and the turbine shaft. While rotating, the oil in the oil tank is pumped to the first hydraulic cylinder and the second hydraulic cylinder. It is achieved by a continuously variable transmission for a vehicle comprising a first oil pump and a second oil pump for supplying.

Another object of the present invention described above is a line pressure regulating valve and a pulley pressure regulating valve for adjusting a pressure of oil drawn from an oil tank through a first oil pump according to a control signal transmitted from a first solenoid and a second solenoid; Pulley pressure alternating valves through which oil flows from these line pressure regulating valves and pulley pressure regulating valves through the first hydraulic line and the second hydraulic line, and oil is selectively supplied from the pulley pressure alternating valves to A pulley control unit (A) having a first hydraulic cylinder and a second hydraulic cylinder for controlling the diameter ratio; A clutch pressure control valve that regulates the pressure of the oil supplied from the first oil pump through the third hydraulic line, and selectively supply the oil supplied by the clutch pressure control valve to the forward clutch and the reverse clutch according to the operation of the selection lever. A clutch control unit (B) having a manual valve and a reverse prevention valve for controlling the flow of oil supplied from the manual valve to the reverse clutch through the fourth hydraulic line in accordance with a control signal transmitted from the third solenoid; A lock-up pressure control valve for regulating the pressure of the oil pumped by the first oil pump from the clutch pressure control valve through the fifth hydraulic line, and the sixth hydraulic line and the seventh hydraulic line according to the control signal transmitted from the fourth solenoid. A lock-up clutch control unit (C) having a lock-up clutch valve for selectively supplying oil flowing from the clutch pressure control valve and the lock-up pressure control valve to the lock-up clutch; In a hydraulic control apparatus for a continuously variable transmission for a vehicle including a TCU for outputting an output signal to first to fourth solenoids according to an input signal such as a vehicle speed, an engine speed, and a throttle valve opening amount, the oil pressure controller is disposed in parallel with the first oil pump. And a second oil pump selectively supplying oil supplied from the oil tank to the inlet of the first oil pump, and oil supplied from the oil tank according to a control signal transmitted from the fifth solenoid to the outlet of the first oil pump. It is achieved by the hydraulic control device of a continuously variable transmission for a vehicle, characterized in that it further comprises a pump control unit (D) having a pump capacity selection valve for controlling to be supplied to either of the inlets of the second oil pump.

Hereinafter, a continuously variable transmission for a vehicle according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. (Parts identical to those of the conventional structure described with reference to FIG. 1 are denoted by the same reference numerals.)

2 is a block diagram showing a gear train of a continuously variable transmission for a vehicle according to the present invention. As shown herein, in the continuously variable transmission for a vehicle according to the present invention, the driving force of the engine is smoothly transmitted to the transmission input shaft 40 through the planetary gear set 30 to improve the oscillation performance. ) Was adopted. In addition, in order to efficiently utilize engine power by adjusting the suction amount of the pump according to the load and operating conditions of the engine, a second oil pump 16 is additionally installed separately from the existing first oil pump 8. One structure was adopted.

Here, the torque converter 12 has the same structure as that widely used in the automatic transmission, and is composed of a pump P, a stator S, and a turbine T. The pump P is fixed to the flywheel through the converter housing and converts the mechanical energy of the engine into the kinetic energy of the fluid. The oil delivered by the pump (P) changes the flow direction while passing through the stator (S), and then rotates the turbine (T), the turbine (T) via the turbine shaft 18, the planetary gear set (30) Is operatively connected to the carrier 32. The lockup clutch 14 is used to reduce slip loss of the torque converter 12 at high speed, and directly connects the converter housing to the hub of the turbine T by frictional connection.

The driving force of the engine input to the turbine shaft 18 through the torque converter 12 is transferred to the connector 46 and the input shaft 40 through the carrier 32 in accordance with the operation of the forward clutch 42 and the reverse clutch 44. Then, the driving pulley 50 is rotated. In accordance with the rotation of the drive pulley 50, the driven pulley 52 is rotated through the belt (V), the rotational force of the driven pulley 56 is differential gear 70 through the driven shaft 58 and the idler shaft 64 ) Is sent to the left and right driving wheels. The power transmission process in the forward and backward directions is the same as the conventional structure described with reference to FIG. 1, and thus a detailed description thereof is omitted.

Apart from the torque converter 12 which transmits the rotational force of the engine transmitted through the flywheel to the carrier 32 of the planetary gear set 30 via the turbine shaft 18, in the preferred embodiment of the present invention, the turbine shaft ( 18) the second oil for supplying the oil in the oil tank to be supplied to the hydraulic valve constituting the hydraulic control device, which will be described later, including the first hydraulic cylinder 54 and the second hydraulic cylinder 52. An oil pump 16 was further installed. The second oil pump 16, together with the first oil pump 8, transmits power to the hydraulic control device according to the current operating conditions, which will be described in detail with reference to FIG.

3 is a circuit diagram showing a hydraulic control apparatus of a continuously variable transmission for a vehicle according to the present invention.

The hydraulic control device of the continuously variable transmission engages each of the gears of the planetary gear set 30 installed in the input shaft 40 to the forward clutch 42 and the reverse clutch 44 to change the rotational direction of the drive pulley 50. In addition to the hydraulic valve for supplying the pressurized fluid, the first hydraulic cylinder 54 and the second hydraulic cylinder 52 for increasing and decreasing the diameter ratio of the driving pulley 50 and the driven pulley 56 are converted into oil. Serves to supply

Looking at the overall configuration of the hydraulic control device that serves this role, the first hydraulic cylinder 54 and the second hydraulic cylinder 52 to increase or decrease the torque of the engine by changing the diameter ratio of the drive pulley 50 and the driven pulley 56 Pulley control unit (A) for controlling the operation of; The forward clutch 42 and the drive pulley 50 and the turbine shaft 18 which rotate when the drive pulley 50 is rotated in the same direction as the turbine shaft 18 to enable forward movement are reversed. A clutch control unit (B) for selectively engaging the reverse clutch (44) to enable the operation; A lock-up clutch control unit (C) for directly connecting the turbine shaft (18) to the flywheel of the engine during high speed travel; It consists of a pump control unit (D) for controlling the operating state of the first oil pump 8 and the second oil pump 16 in accordance with the load of the engine.

Here, the pulley control unit (A) is the oil through the first oil pump (8) by the first solenoid (S1) for opening and closing the flow path in accordance with the control signal of the transmission control unit (hereinafter referred to as TCU) Adjusting the pressure of the oil supplied to the pulley pressure alternating valve 88 according to the control signal transmitted from the line pressure control valve 84 and the second solenoid (S2) for adjusting the pressure of the oil drawn from the tank 72 Alternating pulley pressure through which oil flows from the pulley pressure regulating valve 86 and the line pressure regulating valve 84 and the pulley pressure regulating valve 86 through the first hydraulic line L1 and the second hydraulic line L2. Oil is selectively supplied from the valve 88 and the pulley pressure alternating valve 88 to control the diameter ratio of the driving pulley 50 and the driven pulley 56 to the first hydraulic cylinder 54 and the second hydraulic cylinder. It consists of 52.

The line pressure regulating valve 84 is a relief valve. The line pressure regulating valve 84 controls the pressure of the oil pumped from the oil pump under the control of the first solenoid S1 to form a line pressure and then supplies the hydraulic pressure to the hydraulic line. The pulley pressure regulating valve 86 is a reducing valve and adjusts the outlet pressure. In addition, the pulley pressure alternating valve 88 is a two-position four-way direction switching valve, and the flow path is changed by the second solenoid S2 to the first hydraulic cylinder 54 and the second hydraulic cylinder 52. By supplying oil, the diameter ratio of the driving pulley 50 and the driven pulley 56 is changed to increase and decrease the driving torque of the engine to perform shifting.

Next, the clutch control unit B operates the clutch pressure control valve 90 for adjusting the pressure of the oil supplied from the first oil pump 8 through the third hydraulic line L3 and the selection lever 100. According to the manual valve 92 for selectively supplying the oil supplied by the clutch pressure control valve 90 to the forward clutch 42 and the reverse clutch 44, and to the control signal transmitted from the third solenoid S3. Accordingly, the reverse valve 94 is configured to intercept the flow of oil supplied from the manual valve 92 to the reverse clutch 44 through the fourth hydraulic line L4.

Here, the clutch pressure control valve 96 controls the outlet pressure as a reducting valve. The oil discharged from the clutch pressure control valve 96 is sent to the manual valve 92 through the third hydraulic line L3, and is locked up through the fifth hydraulic line L5 and the seventh hydraulic line L7. It is supplied to the pressure control valve 96 and the lockup clutch valve 98, respectively. The manual valve 92 is linked to the selection lever 100 which is directly operated by the driver to change the flow path, and serves to transfer oil supplied through the clutch pressure control valve 90 to the forward clutch 42.

Reverse valve 94 is controlled by the third solenoid (S3), the oil delivered from the manual valve 92 is supplied to the reverse clutch 44 through the fourth hydraulic line (L4) to the planetary gear set ( The ring gear 38 of 30 is fixed to the transmission housing 20. The reverse prevention valve 94 serves to prevent the reverse clutch 44 from operating when the selection lever and the manual valve 92 connected thereto are shifted to the reverse stage due to a malfunction during the forward driving at a predetermined speed or more. .

The lock-up clutch control unit (C) includes a lock-up pressure control valve (96) for adjusting the pressure of oil pumped by the first oil pump (8) from the clutch pressure control valve (90) via the fifth hydraulic line (L5), The oil flowing from the clutch pressure control valve 90 and the lockup pressure control valve 96 is transferred through the sixth hydraulic line L6 and the seventh hydraulic line L7 according to the control signal transmitted from the fourth solenoid S4. The lockup clutch valve 98 selectively supplies the lockup clutch 14 to the lockup clutch 14.

Here, the lockup pressure control valve 96 is a reducing valve, and supplies oil to the lockup clutch valve 98 through the sixth hydraulic line L6 under the control of the fourth solenoid S4. The lock-up clutch valve 98 is a 2-position 4-way direction changeover valve.

The TCU 80 sends an output signal to the first to fifth solenoids S5 according to input signals such as the vehicle speed, the engine speed, and the throttle valve opening amount transmitted from the vehicle speed sensor, the engine speed sensor, and the throttle opening sensor. Control.

Further, in the hydraulic control apparatus of the present invention, when the configuration of the pump control unit D for controlling the operating state of the first oil pump 8 and the second oil pump 16, the conventional first oil pump described above (8) and a second oil pump (16) which is arranged in parallel with the first oil pump (8) and selectively supplies oil supplied from the oil tank (72) to the inlet of the first oil pump (8). ) And the oil supplied from the oil tank 72 is supplied to either the outlet of the first oil pump 8 or the inlet of the second oil pump 16 according to the control signal transmitted from the fifth solenoid S5. It consists of a pump capacity selector valve 82 to control.

It is well known to those of ordinary skill in the art to supply oil to each of the control valves according to the control of the solenoids S1 to S5 at the time of moving forward and backward using the hydraulic control device having such a configuration. Since the description of the description thereof will be omitted. However, the operation of the first oil pump 8 and the second oil pump 16 which are related to the contents of the present invention will be briefly described according to the load of the engine.

The pump capacity selection valve 82 constituting the pump control unit D may control the outlet of the second oil pump 16 to the line input unit or the first oil pump (e.g., the outlet of the first pump) under the control of the fifth solenoid S5. It is to connect selectively to the inlet of 8), it is a two-position three-way directional valve. This changes the outlet of the second oil pump 16 in accordance with the load of the engine or the current operating conditions.

That is, under vehicle driving conditions such as sudden start or sudden stop, the TCU 80 sends a signal to the fifth solenoid S5 to operate the pump capacity selection valve 82 to control the discharge flow rate of the second oil pump 16 to the first oil. A large amount of oil is supplied to the hydraulic line by being sent to the outlet of the pump 8 to be combined. On the contrary, when a small amount of hydraulic pressure is required, such as quiet driving, the discharge flow rate of the second oil pump 16 is sent to the inlet of the first oil pump 8 to supply a small amount of hydraulic pressure, thereby minimizing engine power loss. do.

According to the present invention described above, since the driving force of the engine is transmitted to the drive pulley of the continuously variable transmission through the torque converter, it is possible to reduce the inflow of the torque shock and rotational vibration of the engine to enable a flexible start. In addition, since the compressed oil can be selectively supplied to various hydraulic control valves of the continuously variable transmission using two pumps having different capacities, there is an advantage of improving fuel efficiency by reducing engine power consumption.

Claims (2)

The planetary gear set 30 which is selectively fixed to the transmission housing 20 and the input shaft 40 in accordance with the operation of the forward clutch 42 and the reverse clutch 44, and the input shaft 40 Rotational force of the input shaft 40 while interlocked with the driving pulley 50 via a driving pulley 50 and a belt V fixed by one end and rotated by an engine driving force transmitted through the planetary gear set 30. Is driven to the differential gear 70 via the driven shaft 58 and the idler shaft 64, and the diameter ratio of the drive pulley 50 and the driven pulley 56 by hydraulic pressure is changed. In a continuously variable transmission for a vehicle including a first hydraulic cylinder (54) and a second hydraulic cylinder (52), A torque converter 12 for transmitting the rotational force of the engine transmitted through the flywheel to the carrier 32 of the planetary gear set 30 via the turbine shaft 18; The first oil pump 8 and the second oil pump 16, which rotates by the turbine shaft 18 and feeds oil in the oil tank and supplies the oil to the first hydraulic cylinder 54 and the second hydraulic cylinder 52. A continuously variable transmission for a vehicle comprising: Line pressure control valve 84 for adjusting the pressure of the oil drawn from the oil tank 72 through the first oil pump 8 in accordance with the control signal transmitted from the first solenoid (S1) and the second solenoid (S2) And a pulley pressure through which oil flows from the pulley pressure regulating valve 86 and the line pressure regulating valve 84 and the pulley pressure regulating valve 86 through the first hydraulic line L1 and the second hydraulic line L2. Oil is selectively supplied from the alternating valve 88 and the pulley pressure alternating valve 88 to control the diameter ratio of the driving pulley 50 and the driven pulley 56 to the first hydraulic cylinder 54 and the second hydraulic pressure. A pulley control unit A having a cylinder 52; A clutch pressure control valve 90 for adjusting the pressure of oil supplied from the first oil pump 8 through a third hydraulic line L3 and the clutch pressure control valve according to the operation of the selection lever 100 ( Manual valve 92 for selectively supplying the oil supplied by 90 to the forward clutch 42 and the reverse clutch 44, and the manual valve 92 in accordance with a control signal transmitted from the third solenoid S3. A clutch control unit (B) having a reverse prevention valve (94) for regulating the flow of oil supplied to the reverse clutch (44) from the fourth hydraulic line (L4) from the back; A lockup pressure control valve 96 for adjusting the pressure of oil pumped by the first oil pump 8 from the clutch pressure control valve 90 through a fifth hydraulic line L5, and a fourth solenoid S4; The oil flowing from the clutch pressure control valve 90 and the lockup pressure control valve 96 through the sixth hydraulic line L6 and the seventh hydraulic line L7 according to the control signal transmitted from the lockup clutch A lockup clutch control unit (C) having a lockup clutch valve (98) for selectively supplying to (14); In the hydraulic control device for a continuously variable transmission for a vehicle comprising a TCU (80) for sending an output signal to the first to fourth solenoid (S4) in accordance with an input signal, such as vehicle speed, engine speed and throttle valve opening amount, A second oil pump 16 disposed in parallel with the first oil pump 8 and selectively supplying oil supplied from the oil tank 72 to an inlet of the first oil pump 8; The oil supplied from the oil tank 72 is supplied to either one of an outlet of the first oil pump 8 and an inlet of the second oil pump 16 according to a control signal transmitted from the fifth solenoid S5. Hydraulic control device for a continuously variable transmission for a vehicle, characterized in that it further comprises a pump control unit (D) having a pump capacity selection valve (82) for controlling.