Contamination indicator

A contamination indicator for filter elements for fluids housed in a filter housing, comprising:

• a fluid-conveying connection in fluid communication with a filter housing interior;
• an indicating device providing information of degree of filter element contamination and having a fluid inlet;
• and
• a temperature-dependent active actuation device being connected upstream of said indicating device in a direction of said fluid inlet of said indicating device and activating said indicating device when a temperature of fluid being filtered has reached a predefinable threshold value, said actuation device including a valve having a movable closing body with a body longitudinal axis, said closing body being biased toward a closed position blocking said fluid inlet of said indicating device and being movable into an open position opening said fluid inlet of said indicating device by a temperature-dependent active positioning device associated with said valve, said positioning device having an expansion element with an element longitudinal axis being connected upstream of said closing body in the direction of said fluid inlet, coming into contact with the fluid and being coupled with said closing body such that said closing body is moved along said body longitudinal axis into the open position through thermal expansion of said expansion element in a direction along said element longitudinal axis applied mechanically to said closing body and in a direction of the thermal expansion of said expansion element, said valve seat being in a valve housing having a fluid passage defined by a stepped bore extending axially through said valve housing, said stepped bore having a step forming said valve seat, said closing body comprising a valve ball, said valve housing including a connection part being on an inlet said of said stepped bore and forming a fluid connection to the dirty side of the filter element, said expansion element including an expansion spring of a metal alloy having shape memory in an end section of said stepped bore adjacent to said connection part, said expansion spring expanding to a greater length upon heating, being supported on one end on said connection part and transmitting a dynamic force on said valve ball against a closing force of said closing spring with another end of said expansion spring upon heating of said expansion spring.

A contamination indicator for filter elements for fluids housed in a filter housing, comprising:

• a fluid-conveying connection in fluid communication with a filter housing interior;
• an indicating device providing information of degree of filter element contamination and having a fluid inlet;
• and
• a temperature-dependent active actuation device being connected upstream of said indicating device in a direction of said fluid inlet of said indicating device and activating said indicating device when a temperature of fluid being filtered has reached a predefinable threshold value, said actuation device including a valve having a movable closing body with a body longitudinal axis, said closing body being biased toward a closed position blocking said fluid inlet of said indicating device and being movable into an open position opening said fluid inlet of said indicating device by a temperature-dependent active positioning device associated with said valve, said positioning device having an expansion element with an element longitudinal axis being connected upstream of said closing body in the direction of said fluid inlet, coming into contact with the fluid and being coupled with said closing body such that said closing body is moved along said body longitudinal axis into the open position through thermal expansion of said expansion element in a direction along said element longitudinal axis applied mechanically to said closing body and in a direction of the thermal expansion of said expansion element, said valve of said actuation device including a valve seat axially abutted by said closing body along said body longitudinal axis under pretensioning of a closing spring, said valve seat being in a valve housing having a fluid passage defined by a stepped bore extending through said valve housing, said stepped bore having a step forming said valve seat, said closing body comprising a valve ball, said closing spring including a compression spring in a spring bore section of said stepped bore extending from said valve seat to an outlet end of said valve housing, said outlet end having a threaded section threadedly receiving a hollow adjustment screw, said closing spring having one end engaging said adjacent screw and an opposite end engaging said valve ball.

A contamination indicator for filter elements for fluids housed in a filter housing, comprising:

• a fluid-conveying connection in fluid communication with a filter housing interior;
• an indicating device providing information of degree of filter element contamination and having a fluid inlet;
• and
• a temperature-dependent active actuation device being connected upstream of said indicating device in a direction of said fluid inlet of said indicating device and activating said indicating device when a temperature of fluid being filtered has reached a predefinable threshold value, said actuation device including a valve having a movable closing body with a body longitudinal axis, said closing body being biased toward a closed position blocking said fluid inlet of said indicating device and being movable into an open position opening said fluid inlet of said indicating device by a temperature-dependent active positioning device associated with said valve, said positioning device having an expansion element with an element longitudinal axis being connected upstream of said closing body in the direction of said fluid inlet, coming into contact with the fluid and being coupled with said closing body such that said closing body is moved along said body longitudinal axis into the open position through thermal expansion of said expansion element in a direction along said element longitudinal axis applied mechanically to said closing body and in a direction of the thermal expansion of said expansion element, said expansion element including an expansion spring of a metal alloy having shape memory, said expansion spring extending axially along a longitudinal axis of said expansion spring to a greater length upon heating thereof and being supported on one side on said closing body and on an opposite side thereof on a stationary part of said valve.