초록 ▼

A hydraulic control system for an automatic transmission, which includes a brake, used to establish a first gear step and a reverse gear step. The hydraulic control system includes a first solenoid valve, a second solenoid valve and a control valve, which is switched by a hydraulic signal from the s

A hydraulic control system for an automatic transmission, which includes a brake, used to establish a first gear step and a reverse gear step. The hydraulic control system includes a first solenoid valve, a second solenoid valve and a control valve, which is switched by a hydraulic signal from the second solenoid valve, and that are operated simultaneously to engage the first-gear step and reverse gear step engagement element; and an neutral gear position engagement control unit that activates both solenoid valves when a shift lever is shifted to neutral to engage the brake. Thus, the generation of a shock may be prevented when the shift lever is shifted from the N position to an R position.

대표청구항 ▼

1. A hydraulic control system for an automatic transmission for a vehicle, comprising: only two valves, namely, a first solenoid valve and a second solenoid valve that are operated simultaneously to engage a first-gear step and reverse gear step engagement element for establishing a first gear step

1. A hydraulic control system for an automatic transmission for a vehicle, comprising: only two valves, namely, a first solenoid valve and a second solenoid valve that are operated simultaneously to engage a first-gear step and reverse gear step engagement element for establishing a first gear step and a reverse gear step; andan N position engagement control unit that allows only the first solenoid valve and the second solenoid valve to be activated while a gear selection device is shifted to a neutral-gear step position to engage the first-gear step and reverse-gear step engagement element,wherein the automatic transmission is operated to establish a plurality of transmission gear steps by selectively operating a plurality of engagement elements including the first-gear step and reverse-gear step engagement element, and wherein the hydraulic control system engages the first-gear step and reverse-gear step engagement element when the gear selection device is shifted to a reverse-gear step position. 2. The hydraulic control system of claim 1, wherein, when the gear selection device is shifted to the neutral-gear step position while the vehicle is stopped, the N position engagement control unit activates both the first solenoid valve and the second solenoid valve to engage the first-gear step and reverse-gear step engagement element, andwherein, while the vehicle is in motion, the N position engagement control unit deactivates both the first solenoid valve and the second solenoid valve to disengage the first-gear step and reverse-gear step engagement element. 3. The hydraulic control system of claim 1, further comprising: a drain flow rate control valve that controls a flow rate of oil drained from the first-gear step and reverse-gear step engagement element. 4. The hydraulic control system of claim 1, further comprising: a switching valve that supplies an output pressure, which is output from either the first solenoid valve or the second solenoid valve to the first-gear step and reverse-gear step engagement element, to either the first-gear step and reverse-gear step engagement element or a second engagement element of the plurality of engagement elements. 5. The hydraulic control system of claim 4, wherein the switching valve switches between supplying a regulation pressure and a holding pressure to the second engagement element. 6. The hydraulic control system of claim 4, wherein, when the automatic transmission enters a transmission gear step, the switching valve is switched to prevent the output pressure from being supplied to the second engagement element. 7. The hydraulic control system of claim 4, further comprising: a drain communication path that communicates a drain path of the switching valve with a drain path of the drain flow rate control valve when the automatic transmission enters a specified transmission gear step. 8. The hydraulic control system of claim 1, further comprising: a hydraulic transmission unit provided in an input side of the automatic transmission;a lock-up clutch, attached to the hydraulic transmission unit;a lock-up clutch switching valve that is switched to engage and disengage the lock-up clutch; anda manual valve for outputting a D-range pressure when the gear selection device is shifted to a D gear step position, wherein the lock-up clutch switching valve is switched by the D-range pressure. 9. A control method for an automatic transmission for a vehicle, comprising: engaging a first-gear step and reverse-gear step engagement element for establishing a first-gear step and a reverse-gear step while a gear selection device is shifted to a neutral gear step position, andwherein the automatic transmission further includes only two valves, namely a first solenoid valve and a second solenoid valve, that are operated simultaneously to engage the first-gear step and reverse-gear step engagement element, and the control method further comprisesactivating only the first solenoid valve and the second solenoid valve to engage the first-gear step and reverse-gear step engagement element when the gear selection device is shifted to a neutral gear step position,wherein the automatic transmission is operated to establish a plurality of transmission gear steps by selectively operating a plurality of engagement elements including the first-gear step and reverse-gear step engagement element, and wherein the first-gear step and reverse-gear step engagement element is engaged when the gear selection device is shifted to a reverse-gear step position. 10. The control method of claim 9, further comprising: activating both the first solenoid valve and the second solenoid valve to engage the first-gear step and reverse-gear step engagement element when the gear selection device is shifted to the neutral gear step position when the vehicle is stopped; anddeactivating both the first solenoid valve and the second solenoid valve to disengage the first-gear step and reverse-gear step engagement element when the vehicle is in motion. 11. The control method of claim 9, further comprising: supplying an output pressure, which is output from either the first solenoid valve or the second solenoid valve to the first-gear step and reverse-gear step engagement element, to either the first-gear step and reverse-gear step engagement element or a second engagement element of the plurality of engagement elements. 12. The control method of claim 11 further comprising: interrupting the supply of the output pressure to the second engagement element when the automatic transmission enters a specified transmission gear step. 13. The control method of claim 9, wherein a hydraulic transmission unit; a lock-up clutch, attached to the hydraulic transmission unit; and a lock-up clutch switching valve that is switched to engage and disengage the lock-up clutch are provided in an input side of the automatic transmission, and the control method further comprises: switching the lock-up clutch switching valve using the D-range pressure when the gear selection device is shifted to a D gear step position.