A self-resetting single-valve hydraulic drive device based on primary and secondary pistons for a push rod engine, comprising:
- a rocker arm assembly, wherein the rocker arm assembly comprises a rocker arm body and a driving oil passage;
- and one end of the rocker arm body is provided with a primary driving piston, and the other end of the rocker arm body is provided with a first elephant foot assembly;
- an integrated cam and push rod assembly, wherein the integrated cam and push rod assembly comprises an integrated cam, and the integrated cam and push rod assembly is provided below the primary driving piston and is configured to drive the rocker arm body to rotate;
- an exhaust valve assembly, wherein the exhaust valve assembly comprises an inner-side exhaust valve and an outer-side exhaust valve;
- a valve bridge assembly, wherein the valve bridge assembly comprises a valve bridge body;
- the valve bridge body is located below the first elephant foot assembly;
- the valve bridge body is provided with a secondary driving piston and an oil drain passage;
- the oil drain passage connects the secondary driving piston with the driving oil passage;
- and the secondary driving piston is connected to the inner-side exhaust valve or the outer-side exhaust valve;
- and
- a limit assembly, wherein the limit assembly is located above the oil drain passage;
- wherein, the driving oil passage connects the primary driving piston with the secondary driving piston;
- the driving oil passage is connected with an engine drive solenoid valve and a drive control valve, and the engine drive solenoid valve and the drive control valve are opened or closed simultaneously;
- when the engine drive solenoid valve is opened and the drive control valve opens the driving oil passage:
- during a drive lift of the integrated cam, the limit assembly is in contact with the valve bridge body and seals the oil drain passage, the primary driving piston and the secondary driving piston are connected to form a hydraulic linkage, the secondary driving piston drives an exhaust valve connected to the secondary driving piston to open, and the rocker arm body and the valve bridge body do not move;
- during a positive-power exhaust lift of the integrated cam, the limit assembly is separated from the valve bridge body, the oil drain passage is opened, the secondary driving piston is reset after oil is drained, the primary driving piston and the rocker arm body are rigidly connected, and the rocker arm body rotates to drive the valve bridge body to open the inner-side exhaust valve and the outer-side exhaust valve;
- and
- when the engine drive solenoid valve is closed and the drive control valve closes the driving oil passage:
- during the drive lift of the integrated cam, the primary driving piston absorbs a drive lift of the integrated cam and push rod assembly for the rocker arm body, the rocker arm body does not move, and the drive lift of the integrated cam is not transmitted to an exhaust valve side;
- during the positive-power exhaust lift of the integrated cam, the primary driving piston and the rocker arm body are rigidly connected, and the rocker arm body rotates to drive the valve bridge body to open the inner-side exhaust valve and the outer-side exhaust valve;
- wherein, the driving oil passage comprises a primary piston oil passage, a secondary piston oil passage and a control valve oil supply passage;
- the primary piston oil passage connects the primary driving piston with the drive control valve;
- the secondary piston oil passage connects the secondary driving piston with the drive control valve;
- the control valve oil supply passage is connected with the drive control valve;
- and the engine drive solenoid valve is connected on the control valve oil supply passage;
- the control valve oil supply passage comprises a rocker arm shaft oil supply passage and a connecting oil supply passage;
- the rocker arm shaft oil supply passage is provided at the rocker arm shaft;
- the connecting oil supply passage is provided at the rocker arm body;
- the connecting oil supply passage connects the rocker arm shaft oil supply passage with the drive control valve;
- the drive control valve comprises a control valve body and a return assembly;
- the return assembly is in contact with the control valve body;
- the rocker arm body is provided with a control valve hole;
- the control valve body is coaxially and slidably provided in the control valve hole;
- and the control valve body is provided with a primary control valve oil passage;
- wherein, when the engine drive solenoid valve is opened, the rocker arm shaft oil supply passage, the control valve oil supply passage and a bottom of the control valve hole are filled with oil, an oil pressure of the bottom of the control valve hole is greater than a force of the return assembly acting on the control valve body, the control valve body moves up to an opened position under an action of the oil pressure, and the primary control valve oil passage connects the primary piston oil passage with the secondary piston oil passage;
- and
- when the engine drive solenoid valve is closed, no oil pressure exists in the rocker arm shaft oil supply passage and the control valve oil supply passage, the control valve body is in a closed position at the bottom of the control valve hole under an action of the return assembly, and the primary control valve oil passage is always connected with the primary piston oil passage and is not connected with the secondary piston oil passage.