SOLENOID DEVICE WITH SENSOR

A solenoid device including pressure altering means for altering an output pressure of the solenoid device; and an actuator for providing an actuating signal to said pressure altering means; wherein the solenoid device further includes a sensor arranged to sense a control value of the solenoid device, and a controller which receives a request and is arranged to control delivery of power to the actuator with feedback from the sensor until the control value meets the request.

FIELD OF THE INVENTION

The present invention relates to a solenoid device and, more particularly but not exclusively, to a solenoid spool valve having an integrated pressure sensor which provides improved performance characteristics when the solenoid spool valve is used in a communications network of a vehicle or system.

BACKGROUND OF THE INVENTION

A modern vehicle typically has a large number of electronic control units (ECU) for various subsystems. The biggest processor is commonly the engine control unit, however other ECUs are used for controlling other devices in the vehicle, such as the transmission, airbags, antilock braking system, cruise control, electric power steering, audio systems, windows, doors, mirror adjustment, battery and recharging systems for hybrid/electric cars, etc. Some of these form independent subsystems, but communications among others are essential. A subsystem may need to control actuators or receive feedback from sensors. The Controller-Area Network (CAN) is a standard vehicle bus or communications network devised to fill this need.

The applicant is aware that existing systems have sensors elsewhere on a hydraulic circuit for sensing pressure delivered by solenoid valves. The applicant has determined that such systems may be improved, at least in so far as performance and maintenance are concerned.

The applicant has also identified that current design high flow solenoids have an equal area spool, meaning that lands of the spool have the same external dimension, usually the outside diameter, resulting in the lands having the same surface area for driving the spool in response to fluid pressure against the lands. To increase the pressure obtained from the current design solenoid spool valves requires the spool diameter to be increased. As the diameters of each of the lands on the spool increase, the force against a diaphragm of the solenoid spool valve increases, necessitating a magnet (coil) size of an electromagnetic actuator to be increased. The applicant has determined that it would be desirable to obviate the necessity to increase the magnet (coil) size with pressure capacity of the solenoid spool valve.

Furthermore, the applicant has also identified that increasing diameters of all lands on the spool in accordance with current practice typically increases leakage to an exhaust port of the solenoid spool valve, requiring a larger pump to compensate for the leakage.

Examples of the invention seek to solve, or at least ameliorate, one or more disadvantages of previous solenoid spool valves.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a solenoid device including pressure altering means for altering an output pressure of the solenoid device; and an actuator for providing an actuating signal to said pressure altering means; wherein the solenoid device further includes a sensor arranged to sense a control value of the solenoid device, and a controller which receives a request and is arranged to control delivery of power to the actuator with feedback from the sensor until the control value meets the request.

Preferably, the solenoid device is a solenoid spool valve including a spool valve having a sleeve provided with a supply port, a control port, and a spool supported in the sleeve for axial displacement within the sleeve; and an electromagnetic actuator for providing an axial drive force to said spool in a first axial direction; wherein the solenoid spool valve further includes a sensor arranged to sense a control value of the spool valve, and a controller which receives a request and is arranged to control delivery of power to the electromagnetic actuator with feedback from the sensor until the control value meets the request.

More preferably, the sensor is a pressure sensor, the supply port is a supply pressure port, the control port is a control pressure port, the control value is a control pressure, the request is in the form of a pressure request, and the controller controls delivery of power to the electromagnetic actuator with feedback from the pressure sensor until the control pressure meets the pressure request.

Preferably, the controller is in the form of a control circuit. More preferably, the control circuit is arranged to receive the pressure request from a communications network. Even more preferably, the communications network is a Controller-Area Network.

Preferably, the pressure sensor is arranged to sense the control pressure of the spool valve at a location inside the sleeve.

In a preferred form, the controller is arranged to adaptively learn current provided to the electromagnetic actuator in relation to pressure sensed, such that the solenoid spool valve is self-compensating.

Preferably, the controller is mounted relative to the sleeve.

It is preferred that the solenoid spool valve including the pressure sensor and controller are provided as a unitary module.

Preferably, the solenoid spool valve further includes an exhaust port, the spool has a first piston with a first land for opening/closing the supply pressure port and a second piston with a second land for opening/closing the exhaust port, wherein the first piston has a larger piston face surface area in fluid communication with the control pressure port than does the second piston.

Preferably, the first piston has one piston face (b) in fluid communication with the control pressure port arranged such that force of fluid against said one piston face acts on the spool in an axial direction away from the electromagnetic actuator, and an opposite piston face (a) in fluid communication with a feedback orifice arranged such that force of fluid against said opposite piston face acts on the spool in an axial direction toward the electromagnetic actuator.

More preferably, the feedback orifice supplies fluid at the same control pressure as the control pressure port. Even more preferably, the feedback orifice is in fluid communication with the control pressure port. In one example, the orifice is formed as a duct extending through the first piston to communicate with the control pressure port.

Preferably, the face (c) of the second piston in fluid communication with the control pressure port is arranged such that force of fluid against said face acts on the spool in an axial direction toward the electromagnetic actuator.

Preferably, the spool is arranged such that, the combined force on the spool from fluid against piston faces of the spool is independent of the transverse extent of the first piston, owing to equal and opposite face surface areas of the first piston. More preferably, the first piston is cylindrical and the combined force on the spool from fluid against piston faces of the spool is independent of an outside diameter of the first piston.

Preferably, the spool is arranged such that, the combined force on the spool from fluid against piston faces of the spool is given by the equation:

where A, B and C are the fluid forces acting on faces a, b and c, respectively.

In a preferred form, the first piston has a larger diameter than the second piston. More preferably, as a result of the larger diameter of the first piston, the valve has relatively high flow from the supply pressure port to the control pressure port and relatively low flow from the control pressure port to the exhaust port.

In accordance with another aspect of the present invention, there is provided a range of solenoid spool valves, each of which is as described above, wherein each of the solenoid spool valves has a different first piston diameter to second piston diameter ratio to provide different pressure capabilities, and wherein each of the solenoid spool valves has an identical electromagnetic actuator.

In one particular example, each of the solenoid spool valves has a different first piston diameter, and the same second piston diameter.

However, a learned person can appreciate that the technology described herein does not need to be limited to solenoids having spool valves and could be incorporated into other solenoid types that can alter pressure through other control means, for example, by controlling the exhausting of oil from a control chamber, fed by a controlled source, ie an orifice, in a controlled manner, thus effecting pressure control. The integration of the pressure sensor and controls in this case would be key to the repeatable pressure output from this previously non-self-regulating system/solenoid.

DETAILED DESCRIPTION

With reference toFIG. 1of the drawings, there is provided a solenoid spool valve10used for supplying varying pressures from a system supply pressure to an object (such as, for example, a friction clutch). The solenoid spool valve10is advantageously provided with a pressure sensor46and a controller48to achieve improved performance/convenience when used in a communications network such as a Controller-Area Network (CAN).

More specifically, the applicant has determined that existing systems typically use a sensor elsewhere on a hydraulic circuit, separate to the solenoid spool valve. The applicant has determined that such arrangements are disadvantageous, particularly when it comes to rebuilding and maintenance. Specifically, as existing systems supply the solenoid spool valve with a current and use an external pressure sensor to sense pressure achieved by the solenoid spool valve, components of the system separate to the solenoid spool valve may have to adapt to wear of the solenoid spool valve as it may deteriorate over time and change its characteristics. Then, when the solenoid spool valve is replaced with a fresh solenoid spool valve, the remainder of the system must re-learn to accommodate the new solenoid spool valve which has different characteristics to the replaced solenoid spool valve. The applicant has determined that it would be advantageous for there to be provided a solenoid spool valve which has its own pressure sensor and controller such that the solenoid spool valve is sent a pressure request rather than a current, as is typical in existing systems. In this way, the components of the system external to the solenoid spool valve do not need to compensate for the change in characteristics of the Solenoid spool valve which are dealt with internally of the solenoid spool valve by virtue of its ability to be self-compensating. The pressure sensor46is in the control pressure circuit of the solenoid spool valve10, and there is feed from the CAN such that an input pressure may be requested and controlled at the source of the signal (ie. within the solenoid). The pressure signal is fed back to the solenoid controller48from the pressure sensor46.

More specifically, the solenoid spool valve10includes a spool valve12having a sleeve14provided with a supply pressure port16, a control pressure port18and a spool22supported in the sleeve14for axial displacement within the sleeve14. The solenoid spool valve10also includes an electromagnetic actuator24for providing an axial drive force to the spool22in a first axial direction away from the electromagnetic actuator24so as to operate the spool valve12. The solenoid spool valve10further includes the pressure sensor46arranged to sense a control pressure of the spool valve12, and the controller48which receives a pressure request and is arranged to control delivery of power to the electromagnetic actuator24with feedback from the pressure sensor46to meet the pressure request.

The controller48may receive the pressure request from the communications network by way of communication means such as, for example, communication wires50. Similarly, the pressure sensor46may be coupled in communication with the controller48by way of communication wires52. The controller48shown inFIG. 1supplies power to the electromagnetic actuator24by way of power lines54. However, an alternative to this arrangement can be the combining of the power and CAN wires in that the CAN signal is “injected” on top of the power wires thus requiring only 2 wires to be connected to the solenoid assembly.

In the example shown, the pressure sensor46is located in a cavity of the sleeve14near a bore of the spool valve12so as to sense the pressure of fluid (gas or liquid) in the control pressure circuit in communication with the control pressure port18. The controller48is mounted relative to the sleeve14and may be arranged to adaptively learn current provided to the electromagnetic actuator24in relation to pressure sensed by the pressure sensor46, such that the solenoid spool valve10is self-compensating.

Advantageously, as the solenoid spool valve10including the pressure sensor46and controller48is provided as a unitary module, the entire module is able to be replaced at the end of its life without any need for an external controller to adapt to the new unit as it performs its own conversion of the desired pressure to the power requirements of the electromagnetic actuator24.

In the example shown inFIG. 1, the solenoid spool valve12is a two land high flow solenoid spool valve which enables higher control pressures to be used without necessitating a correspondingly larger electromagnetic actuator. A similar solenoid spool valve12is shown inFIG. 2(a), and is described below. In the subsequent figures, there are shown examples of alternative solenoid spool valves12which may also be adapted to include a pressure sensor46and controller48in the manner shown inFIG. 1so as to embody alternative configurations of the present invention.

With reference toFIG. 2(a) there is shown a solenoid spool valve10used for supplying varying pressures from a system supply pressure to an object (such as, for example, a friction clutch). The solenoid spool valve10shown has an increased supply pressure diameter of the spool while leaving the regulated pressure end of the spool at the original diameter. By virtue of this configuration, the resultant force on a diaphragm of the valve10is independent of the increased supply pressure diameter.

More specifically, the solenoid spool valve10includes a spool valve12having a sleeve14provided with a supply pressure port16, a control pressure port18, an exhaust port20and a spool22supported in the sleeve14for axial displacement within the sleeve14. The solenoid spool valve10also includes an electromagnetic actuator24for providing an axial drive force to the spool22in a first axial direction away from the electromagnetic actuator so as to operate the spool valve12. The spool22has a first piston26with a first land28for opening/closing the supply pressure port16, and a second piston30with a second land32for opening/closing the exhaust port20. The first piston26has a larger piston face surface area34in fluid communication with the control pressure port18than does the second piston30.

The first piston26has one piston face (b) in fluid communication with the control pressure port18, arranged such that force of fluid against the face (b) acts on the spool22in an axial direction away from the electromagnetic actuator24. The first piston26also has an opposite piston face (a) in fluid communication with a feedback orifice36arranged such that force of fluid against the opposite piston face (a) acts on the spool22in an axial direction toward the electromagnetic actuator24. The feedback orifice36supplies fluid at the same control pressure as the control pressure port18. In the example shown inFIG. 2(a), the feedback orifice36is formed in the sleeve14so as to provide fluid at the control pressure to piston face (a) of the first piston26.

FIGS. 2(b) to2(d) show alternative configurations of solenoid spool valves10in accordance with other examples of the present invention. More specifically, with reference toFIG. 2(b), the solenoid spool valve10shown in this example is similar to the example shown inFIG. 2(a), except in that the feedback orifice36is located in an end of the spool valve12, rather than in a side wall of the sleeve14. With reference to the example shown inFIG. 2(c), the feedback orifice36is provided in a sidewall of the sleeve14(in a manner similar to that inFIG. 2(a)), however this example differs in that the sleeve14is non-circular, in contrast to the examples inFIGS. 2(a),2(b) and2(d). This is made evident by the cross-sectional depiction of the sleeve14inFIG. 2(c), wherein the sleeve14extends to a greater degree below the spool22than it does above the spool22.

The solenoid spool valve10shown inFIG. 2(d) has a feedback orifice36formed as a duct38extending through the first piston26to communicate with the control pressure port18. Also, the example shown inFIG. 2(d) incorporates a damper40as part of the solenoid spool valve10. As can be seen, the size of the magnet42is common to all four versions of the solenoid spool valve10shown in.FIGS. 2(a) to2(d), as all four versions use an identical electromagnetic actuator24.

In each of the solenoid spool valves10shown inFIGS. 2(a) to2(d), the face (c) of the second piston30in fluid communication with the control pressure port18is arranged such that force of fluid against that face (c) acts on the spool22in an axial direction toward the electromagnetic actuator24.

With reference toFIG. 3, the spool22is arranged such that, for any stationary position of the spool valve (including when the supply pressure port16of the solenoid spool valve10is closed as shown), the combined force on the spool22from fluid against piston faces of the spool22is independent of the transverse extent of the first piston26. This independence is due to equal and opposite face surface areas of the first piston26, which effectively cancel each other. Where the first piston26is cylindrical, the combined force on the spool22from fluid against piston faces of the spool22is independent of an outside diameter of the first piston26. With regard to the lettering shown inFIG. 3, the combined force on the spool22from fluid against piston faces of the spool22is given by the equation:

Combined force=A+C−B,whereA, BandCare the fluid forces acting on faces (a), (b) and (c), respectively.

In this way, the force on the annular part of surface (a) represented by the six outermost arrows of A cancel out the forces on surface (b) represented by the six arrows of force B, such that the combined force is truly independent of the outside diameter of the first piston26.

Where the spool is cylindrical, the first piston26has a larger diameter than the second piston30so that the first piston26has a larger piston face surface area in fluid communication with the control pressure port18than does the second piston30. As a result of the larger diameter of the first piston26, the valve10has relatively high flow from the supply pressure port16to the control pressure port18and relatively low flow from the control pressure port18to the exhaust port20. This is desirable, as the relatively low flow from the control pressure port18to the exhaust port20minimises leakage such that a smaller pump may be used.

Advantageously, the ability to increase the diameter of the first piston26enables higher control pressure to be used, assisting in the regulation of higher pressures and facilitating quick action of the solenoid spool valve10. Also, as the size of magnet42is independent of the flow area design, the pressure can be adjusted by varying the diameter of the first piston26while maintaining a common coil/core size between pressure/flow variants. This may assist in maintaining an overall short length when compared with other high flow solenoids, and facilitates the provision of a family of solenoid designs using a common magnet coil/core and body.

The tunable feedback orifice36may have a maximised effect by being located to cooperate with the largest area of the spool22.

The solenoid spool valve10may have a filled canister whereby oil is provided inside the electromagnetic actuator to change the natural frequency of the solenoid spool valve10. Also, a trimming screw44may be mounted as shown inFIGS. 2(a) to2(d).

With reference toFIG. 4, there is shown a diagrammatic view of an example system incorporating a solenoid spool valve10in accordance with the invention. In the example shown, the solenoid spool valve10is used in combination with a seat base/cushion56to control operation of the seat base/cushion. In particular, the solenoid spool valve10receives information from a sensor46via an on board controller (OBC)48. The OBC is connected by wiring to a master controller58.

FIG. 5shows an example system incorporating a plurality of solenoid spool valves10, each of which is provided with a separate OBC48, and an individual identifier such that the individual solenoid spool valves10are able to be operated individually. The solenoid spool valves10are connected by communication wires50. The communication wires50can be a combination of the power and CAN wires such that the CAN signal is “injected” on top of the power wires thus requiring only two wires to be connected to each solenoid assembly. As the communication wires50connect to the master controller58in an endless loop, this allows for continued power and CAN communication from either direction in the even that a wire or connection is faulty, thus making the system more robust and failsafe.

FIG. 6shows an OBC48of a solenoid spool valve10with a series of possible CAN nodes that could be used by the OBC48to measure responses. More specifically, the diagram shows a range of different sensors46that could be used by the OBC48to measure responses, depending on the nature of the request quantity type which is received by the OBC48. In each case, the sensor46is arranged to sense a control value of the spool valve, and the OBC48receives a request and is arranged to control delivery of power to the electromagnetic actuator of the solenoid spool valve10with feedback from the sensor46until the control value meets the request.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

The CAN solenoid spool valve (CS) of examples of the present invention is the combination of several technologies into one device that enables that device to:self control its own pressure output based on a CAN signal from a master controller;be self compensating for wear;be self compensating for changes in ambient conditions (ie temperature, pressure, fluid viscosity, leakage); andbe able to be commonised and calibrated according to customer requirements by simple programming.

In one variation of the design the CS includes a solenoid spool valve having the ability to produce varied pressure outputs, with the integration of a pressure sensor into the control port and a small on-board controller that is supplied power and a CAN signal from a master controller and is able to drive the solenoid spool to achieve the desired pressure output independent of wear, leakage, temperature and inlet pressure to achieve the desired result.

In another variation of the design the CS includes a solenoid spool valve having the ability to produce varied flow outputs, with the integration of a flow sensor into the control port and a small on-board controller that is supplied power and a CAN signal from a master controller and is able to drive the solenoid spool to achieve the desired flow output or speed independent of wear, leakage, temperature and inlet pressure to achieve the desired result.

In another variation of the design the CS includes a solenoid spool valve having the ability to produce varied flow outputs, with the integration of a temperature sensor into the control port and a small on-board controller that is supplied power and a CAN signal from a master controller and is able to drive the solenoid spool to achieve the desired temperature independent of wear, leakage, temperature and inlet pressure to achieve the desired result (ie coolant control valve).

In yet another variation of the design the CS includes a solenoid spool valve having the ability to produce varied flow outputs, with the integration of a speed sensor to measure engine speed and a small on-board controller that is supplied power and a CAN signal from a master controller and is able to drive the solenoid spool to achieve the desired speed output independent of wear, leakage, temperature and inlet pressure to achieve the desired result.

In still another variation of the design the CS includes an actuator motor having the ability to produce position control, the integration of a position sensor onto the output and a small on-board controller that is supplied power and a CAN signal from a master controller and is able to drive the actuator to achieve the desired position independent of wear, leakage, temperature and voltage supply.

The CS controller is connected to power and can be interconnected to the master controller via CAN as separate wires, or can also be linked via CAN-Over-Power, radio links, Bluetooth or otherwise as examples. The CS can also use other sensors already existing on the CAN to effect the desired results and monitor its performance.

The CS would automatically adjust itself to wear over its lifetime and adjust itself to suit its environment.

The CS can be “labelled” to have a distinguishing number or identifier so that many solenoids of the same type can be used on the same CAN line where only the identifier is different so that each solenoid has its own unique ID address so that when CAN requests a pressure change, it could ask each solenoid individually to perform the change as requested and when requested.

Using an example of a CS controlling pressure, the following is offered:(i). Ignition is turned on in vehicle and engine is started(ii). Driver engages Drive gear(iii). Master controller sends a signal to the solenoid via CAN requesting a ramp up of pressure over time to effect a smooth engagement of drive gear in the transmission(iv). The solenoid self regulates the pressure at the desired increasing rate as instructed, compensating for wear, leakage and temperature to achieve the desired rate of change of pressure(v). Once the function is completed, the solenoid sends a signal back over CAN to the master controller to confirm the function requested has completed, or, the solenoid is unable to complete the task and the reason eg. pressure too low, pressure too high, etc (error message whereby the Master controller adopts a failsafe mode)

Variations of the invention include but are not limited to:(a). An Idle Air Control Solenoid for Internal Combustion Engines with an integrated speed sensor and controller that will adjust air bleed bypass to the engine at idle to control idle speed at the request of the engine ECU over CAN. The idle air solenoid would automatically adjust the airflow to achieve the desired engine idle speed based on its own integrated speed sensor.(b). A centre-neutral logic control solenoid that would control hydraulic oil in industrial/mining machines where the integrated sensor(s) and controller would perform the dual purpose of providing control pressure to the correct pressure port as directed via CAN (left on or right on) and would feed back information to the main machine control unit if the incorrect pressure has been achieved, or if there is pressure caused by leakage into the control circuit that has not been requested by the solenoid controller, thus enabling a safety shutdown of the machine due to unplanned/uncommanded actions.(c). Any device that requires flow control, speed control or position control that is normally controlled via the supplying of current or voltage to the device to achieve control whereby the resulting feedback is not monitored and corrected for at the device itself by the use of integrated sensors and local control.