Method and apparatus for tensioning a chain of an internal combustion engine

A method for tensioning the chain of a chain drive assembly so as to reduce noise, vibration or wear of the chain in an internal combustion engine, the drive assembly including a chain tensioner comprising a hydraulically operated plunger that is moveable within a housing, a fluid chamber defined between the plunger and housing for containing hydraulic fluid, the fluid serving to activate and damp movement of the plunger, biasing means to bias the plunger outwards of its housing, a passage in said housing to provide communication between the chamber and the fluid supply from the engine, and control valve means in said passage for controlling the pressure of the hydraulic fluid supplied to the housing, the method comprising the steps of:

• measuring an operational parameter of the engine or drive assembly,
• measuring a location of the plunger within the housing,
• calculating the desired chain tension in response to the measured operational parameter, and
• transmitting a control signal to the chain tensioner so as to operate the control valve means to increase and decrease the hydraulic pressure supplied to the housing and therefore to control the projection of the plunger to apply the desired chain tension.

A chain drive assembly for reducing noise, vibration or wear of a chain in the assembly an internal combustion engine, the assembly comprising:

• a) a chain tensioner mounted on said engine, the tensioner comprising:
• i) a housing;
• ii) a hydraulically actuated plunger for engaging the chain, the plunger being movable within said housing the plunger comprising a plurality of plunger members;
• iii) a plurality of discrete fluid chambers defined in the housing for containing hydraulic fluid, each plunger member being received in a respective chamber and each plunger member having a different working surface area presented to the hydraulic fluid, the hydraulic fluid serving to activate and damp movement of the plunger member received in the respective chamber;
• iv) biasing means to bias the plunger out of the housing;
• v) a passage in said housing to a provide communication between the chambers and a fluid supply from the engine;
• vi) conduit means connecting a supply of hydraulic fluid in the engine to said passage;
• b) control means for directing the hydraulic fluid to one or more of the chambers in the housing for increasing and decreasing the pressure of the hydraulic fluid;
• c) means for measuring a location of the plunger within the housing,
• d) means for measuring an operational parameter of the engine or drive assembly;
• e) means for calculating the desired chain tension in response to the measured operational parameter;
• and
• f) means for transmitting a control signal to the chain tensioner so as to operate the control means to direct the hydraulic fluid supplied to the appropriate chamber or chambers so as to control the projection of the plunger and to apply the desired chain tension.

A method for tensioning the chain of a chain drive assembly so as to reduce noise, vibration or wear of the chain in an internal combustion engine, the drive assembly including a chain tensioner comprising a hydraulically operated plunger that is moveable within a housing, a plurality of discrete fluid chambers defamed in the housing for containing hydraulic fluid, biasing means to bias the plunger outwards of its housing, a passage in said housing to provide communication between the chambers and the fluid supply from the engine, the plunger having a plurality of plunger members, each plunger member being received in a respective chamber and each having a different working surface area presented to the fluid, the fluid serving to activate and damp movement of the plunger member in the respective fluid chamber, and control valve means for directing the hydraulic fluid to one or more of the chambers for increasing and decreasing the pressure of the hydraulic fluid, the method comprising the steps of:

• measuring an operational parameter of the engine or drive assembly;
• measuring a location of the plunger within the housing;
• calculating the desired chain tension in response to the measured operational parameter;
• and
• transmitting a control signal to the chain tensioner so as to operate the control valve means to direct the hydraulic fluid to the appropriate chamber or chambers so as to control the projection of the plunger and therefore to apply the desired chain tension.

A chain drive assembly for reducing noise, vibration or wear of a chain in the assembly an internal combustion engine comprising a chain tensioner comprising;

• a) a chain tensioner mounted on said engine, the tensioner comprising:
• i) a housing;
• ii) a hydraulically actuated plunger for engaging the chain, the plunger being movable within said housing;
• iii) a fluid chamber defined between the plunger and the housing for containing hydraulic fluid, the fluid serving to activate and damp movement of the plunger;
• iv) electrically actuated biasing means to bias the plunger out of the housing;
• v) a passage in said housing to provide communication between the chamber and a fluid supply from the engine;
• b) conduit means connecting a supply of hydraulic fluid in the engine to said passage;
• c) control means for controlling the biasing force applied by the biasing
• d) means for measuring a location of the plunger within the housing;
• e) means for measuring an operational parameter of the engine or drive assembly;
• f) means for calculating the desired chain tension in response to the measured operational parameter;
• g) means for determining the hydraulic pressure of the fluid in the chamber;
• h) means for transmitting a control signal to the chain tensioner so as to operate the control means to control the biasing force applied to the biasing means and therefore to control the projection of the plunger to apply the desired chain tension, and to switch off the biasing means when the determined hydraulic pressure reaches a predetermined threshold.

A method for tensioning the chain of a chain drive assembly so as to reduce noise, vibration or wear of the chain in an internal combustion engine, the drive assembly including a chain tensioner comprising a hydraulically operated plunger that is moveable within a housings a fluid chamber defined between the plunger and housing for containing hydraulic fluid, the fluid serving to activate and damp movement of the plunger, electrically actuated biasing means for biasing the plunger outwards of its housing, a passage in said housing to provide communication between the chamber and the fluid supply from the engine, and control means for controlling the biasing force applied by the biasing means, the method comprising the steps of:

• measuring an operational parameter of the engine or drive assembly;
• measuring a location of the plunger within the housing;
• calculating the desired chain tension in response to the measured operational parameter;
• and
• transmitting a control signal to the chain tensioner so as to operate the control means to control the biasing force applied by the biasing means thereby controlling the projection of the plunger to apply the desired chain tension,
• determining the hydraulic pressure in the chamber,
• switching off the biasing means when the determined hydraulic pressure reaches a predetermined threshold value.