Patent Application
20070246111
The present invention relates generally to valves for vehicle hydraulic systems such as automatic transmission systems.
Modern vehicles have many control systems in which a controller, in response to sensor signals, actuates vehicle components to control the vehicle. As one illustration, an engine control module (ECM) might receive input from various sensors and in response turn “on” and “off” actuation coils of various hydraulic valves to cause an automatic transmission to shift.
Spool valves are one type of valve that can be used for hydraulic control purposes. The valves in essence control the flow or pressure of the hydraulic fluid through various fluid chambers by causing a spool to slide within a valve housing, opening and closing various ports in the housing as it does so. Typically, the ports include a supply port that is connected to a hydraulic fluid supply, an exhaust port that exhausts fluid back to the hydraulic fluid supply, and a control port that is connected to the component sought to be controlled, e.g., to a transmission component.
In some applications it is desirable that the control flow or pressure which is output from the valve be proportional to the input electrical signal provided to the actuating solenoid. As critically recognized herein, fluctuations in supply fluid pressure (as can happen due to supply fluid pump vagaries) can reduce the performance of the valve. With this critical recognition in mind, the invention herein is provided.
A valve has a valve body defining an exhaust port, a supply port, and a control port. A spool is disposed in the valve body and reciprocates therein between a closed configuration, wherein the supply port is fluidly isolated from the control port, and an open configuration, where fluid communication is established between the supply port and control port. An end piston of the spool is juxtaposed with a chamber formed by a closed end of the valve body. A bleed passageway is formed in the spool from the chamber to an exit port juxtaposed with the exhaust port, and structure is provided on the spool to allow fluid, in at least one configuration intermediate the open and closed configurations, to communicate from the control port to the chamber, with the fluid also being permitted to flow from the chamber through the bleed passageway and out of the exhaust port to ameliorate the effect of fluctuations in fluid supplied to the valve. Fluid is not permitted to flow from the control port to the chamber in the open configuration.
The structure may include a radial step formed on the end piston of the spool. The radial step is not in the control port in the open configuration but it is in the control port in the intermediate configuration. Alternatively, the structure may include at least one axially-oriented groove formed in the outer wall of the end piston and extending from a chamber face toward, but not reaching, a control port face. Fluid cannot flow past the end piston in the open configuration but fluid can flow through the groove into the chamber in the intermediate configuration. In still another implementation the structure includes a control passageway having a control entry port blocked by the valve body in the open configuration and not blocked in the intermediate configuration.
In another aspect, a valve has a valve body defining an exhaust port, a supply port, and a control port. A spool is disposed in the valve body and reciprocates therein between a closed configuration, wherein the supply port is fluidly isolated from the control port, and an open configuration, where fluid communication is established between the supply port and control port. An end piston of the spool is juxtaposed with a chamber formed by a closed end of the valve body. A bleed passageway is formed in the spool from the chamber to an exit port juxtaposed with the exhaust port. The end piston allows fluid, in at least one configuration intermediate the open and closed configurations, to communicate from the control port to the chamber, with the fluid also being permitted to flow from the chamber through the bleed passageway and out of the exhaust port to ameliorate the effect of fluctuations in fluid supplied to the valve. Fluid is not permitted to flow from the control port to the chamber in the open configuration.
In another aspect, a valve has a valve body defining an exhaust port, a supply port, and a control port. A spool is disposed in the valve body and reciprocates therein between a closed configuration, wherein the supply port is fluidly isolated from the control port, and an open configuration, where fluid communication is established between the supply port and control port. An end piston of the spool is juxtaposed with a chamber formed by a closed end of the valve body. A bleed passageway is formed in the spool from the chamber to an exit port juxtaposed with the exhaust port. Means are provided for allowing fluid, in at least one configuration intermediate the open and closed configurations, to communicate from the control port to the chamber, the means for allowing fluid also permitting fluid to flow from the chamber through the bleed passageway and out of the exhaust port in the configuration intermediate the open and closed configurations to ameliorate the effect of fluctuations in fluid supplied to the valve.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which:
The present invention is intended for application in automotive vehicle transmission systems and will be described in that context. It is to be understood, however, that the present invention could also be successfully applied in many other applications. Other applications include but are not limited to vehicle heavy equipment applications, engine cam phasing, etc.
Referring initially to
In the closed configuration shown in
In contrast, as the valve 10 is moving between the open and closed configurations, an intermediate situation shown in
The combination of restricted fluid flow in the intermediate configuration between the supply port 24 and control port 22, between the control port 22 and the chamber 38, and between the chamber 38 and exit port 40 ameliorates the effect of fluctuations in fluid supplied through the supply port 24. The fluid flow in the intermediate configuration shown in
Instead of or in addition to the radial step 51 in the end piston 32,
While the particular VALVE WITH CONTROL PORT VENT TO AMELIORATE SUPPLY PRESSURE FLUCTUATION as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and is thus representative of the subject matter which is broadly contemplated by the present invention, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more”. It is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.
