Method of controlling clutch pressure of transmission and control apparatus therefor

A clutch pressure control apparatus of a transmission, comprising:

• a flow amount detecting valve which detects that a clutch chamber is full of an oil;
• a pressure control valve which supplies an oil to the clutch chamber at a time of engaging the clutch, whereby the clutch chamber is full of the discharge oil, gradually increases a hydraulic pressure in the clutch chamber after the flow amount detecting valve detects that the clutch chamber is full of the oil so as to engage the clutch, and drains the oil in the clutch chamber to a tank at a time of disengaging the clutch;
• and
• a supply bypass valve which directly supplies the oil to the clutch chamber from the hydraulic pump by bypassing the pressure control valve at a time of engaging the clutch.

A clutch pressure control apparatus of a transmission, comprising:

• a flow amount detecting valve which detects that a clutch chamber is full of an oil;
• a pressure control valve which supplies an oil to the clutch chamber at a time of engaging a clutch, whereby the clutch chamber is filled with the discharge oil, gradually increases a hydraulic pressure in the clutch chamber after the flow amount detecting valve detects that the clutch chamber is filled with the oil so as to engage the clutch, and drains the oil in the clutch chamber to a tank at a time of disengaging the clutch;
• a supply bypass valve which directly supplies the oil to the clutch chamber from the hydraulic pump by bypassing the pressure control valve at a time of engaging the clutch;
• and
• a discharge bypass valve which directly drains the oil in the clutch chamber to the tank by bypassing the pressure control valve at a time of disengaging the clutch.

A method of controlling a clutch pressure of a transmission structured such as to supply an oil to a clutch chamber via a pressure control valve and directly supply the oil to the clutch chamber from a hydraulic pump by bypassing the pressure control valve by a supply bypass valve, at a time of engaging a clutch, comprising the steps of:

• opening both of the pressure control valve and the supply bypass valve at a time of engaging the clutch;
• closing only the supply bypass valve after a first predetermined time has passed from a time of instructing a start of an engagement;
• making an opening degree of the pressure control valve smaller than an opening degree at a time of instructing the start of the engagement after a second predetermined time which is greater than the first predetermined time has passed from the time of instructing the start of the engagement;
• and
• thereafter, supplying the oil to the clutch chamber till the clutch chamber is full of the oil.

A method of controlling a clutch pressure of a transmission structured such as to supply an oil to a clutch chamber iva a pressure control valve and directly supply the oil to the clutch chamber from a hydraulic pump by bypassing the pressure control valve by a supply bypass valve, at a time of engaging a clutch, comprising the steps of:

• opening both of the pressure control valve and the supply bypass valve at a time of engaging the clutch;
• closing only the supply bypass valve after a first predetermined time has passed from a time of instructing a start of an engagement;
• and
• thereafter, supplying the oil to the clutch chamber only by the pressure control valve till the clutch chamber is full of the oil.