Hydraulic pressure control unit

The present disclosure obtains a hydraulic pressure control unit capable of appropriately diagnosing presence or absence of fixation of an electromagnetic valve. In the hydraulic pressure control unit according to the present disclosure, a controller includes: an acquisition section that acquires a current value of a current flowing through a coil of the electromagnetic valve in a hydraulic pressure control mechanism; and a diagnosis section that determines whether the current value has exhibited behavior of being temporarily reduced in a process in which the current value is increased at initiation of applying the current to the coil of the electromagnetic valve, so as to diagnose the presence or the absence of the fixation of the electromagnetic valve.

This application claims priority under 35 U.S.C. § 119 to patent application number JP 2018-097794 filed on May 22, 2018 in Japan, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a hydraulic pressure control unit capable of appropriately diagnosing presence or absence of fixation of an electromagnetic valve.

2. Description of the Background Art

Conventionally, a vehicle behavior control system that uses a hydraulic pressure of a hydraulic fluid to control behavior of a vehicle such as a motorcycle has been available. In such a vehicle behavior control system, a hydraulic pressure control unit is used to control the hydraulic pressure generated by the hydraulic fluid. More specifically, the hydraulic pressure control unit operates an electromagnetic valve that is provided in a channel for the hydraulic fluid, so as to control the hydraulic pressure generated by the hydraulic fluid.

As a state of the electromagnetic valve, there is a state called fixation that disallows movement of an armature as a movable portion of the electromagnetic valve. When the electromagnetic valve is fixed, it is difficult to appropriately control the hydraulic pressure of the hydraulic fluid by the hydraulic pressure control unit. Thus, for example, in order to notify a driver of the fixation of the electromagnetic valve and urge the driver to repair the electromagnetic valve, it is necessary to diagnose presence or absence of the fixation of the electromagnetic valve. For example, in JP-A-5-58539, such a technique is disclosed that presence or absence of mechanical failure such as the fixation of the electromagnetic valve is diagnosed in a brake system on the basis of a current value of a current flowing through a coil of the electromagnetic valve.

SUMMARY OF THE INVENTION

However, it cannot be said that the conventional technique such as the technique disclosed in JP-A-5-58539 is sufficient for the appropriate diagnosis of the presence or the absence of the fixation of the electromagnetic valve. Thus, it is desired to further appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve. For example, according to the technique disclosed in JP-A-5-58539, in a process in which the current value of the current flowing through the coil of the electromagnetic valve is increased at initiation of applying the current to the coil, the presence or the absence of the fixation of the electromagnetic valve is diagnosed on the basis of a degree of deviation of a detected value of the current value from a value that is set in advance as an assumed current value when the fixation of the electromagnetic valve does not occur. Meanwhile, regardless of the presence or the absence of the fixation of the electromagnetic valve, the current value of the current flowing through the coil of the electromagnetic valve possibly varies in accordance with a temperature of the hydraulic fluid and the like, for example. Thus, in the diagnosis method as described above, it may be difficult to appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve.

The present invention has been made with the above-described problem as the background and therefore obtains a hydraulic pressure control unit capable of appropriately diagnosing presence or absence of fixation of an electromagnetic valve.

A hydraulic pressure control unit according to the present invention is a hydraulic pressure control unit used for a vehicle behavior control system, and includes: a hydraulic pressure control mechanism that includes a base body and components assembled in the base body and including an electromagnetic valve that controls a hydraulic pressure generated by a hydraulic fluid for the vehicle behavior control system; and a controller that includes a control section controlling operation of the components. The controller includes: an acquisition section that acquires a current value of a current flowing through a coil of the electromagnetic valve; and a diagnosis section that determines whether the current value has exhibited behavior of being temporarily reduced in a process in which the current value is increased at initiation of applying the current to the coil of the electromagnetic valve, so as to diagnose presence or absence of fixation of the electromagnetic valve.

In the hydraulic pressure control unit according to the present invention, the controller includes: the acquisition section that acquires the current value of the current flowing through the coil of the electromagnetic valve in the hydraulic pressure control mechanism; and the diagnosis section that determines whether the current value has exhibited the behavior of being temporarily reduced in the process in which the current value is increased at the initiation of applying the current to the coil of the electromagnetic valve, so as to diagnose the presence or the absence of the fixation of the electromagnetic valve. Accordingly, the presence or the absence of the fixation of the electromagnetic valve can be diagnosed without relying on a change in a parameter (for example, a temperature of a hydraulic fluid, or the like) that has an influence on the current value of the current flowing through the coil of the electromagnetic valve. Therefore, it is possible to further appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve.

DETAILED DESCRIPTION OF THE INVENTION

A description will hereinafter be made on a hydraulic pressure control unit according to the present invention with reference to the drawings. Note that a description will hereinafter be made on a hydraulic pressure control unit that is used in a brake system for a two-wheeled motorcycle. However, the hydraulic pressure control unit according to the present invention may be used in a vehicle behavior control system (for example, a system that controls a damping force of a suspension, or the like) other than the brake system. For example, when the hydraulic pressure control unit according to the present invention is used in the system that controls the damping force of the suspension, it is possible to appropriately diagnose presence or absence of fixation of an electromagnetic valve that controls a hydraulic pressure to be generated by a hydraulic fluid in such a system. In addition, the hydraulic pressure control unit according to the present invention may be used in a vehicle behavior control system for a vehicle other than the two-wheeled motorcycle (for example, another straddle-type vehicle, such as an all-terrain vehicle, a three-wheeled motorcycle, or a bicycle, a four-wheeled vehicle, or the like). The straddle-type vehicle means a vehicle that a driver straddles. In addition, a description will hereinafter be made on a case where each of a front-wheel brake mechanism and a rear-wheel brake mechanism is provided in one unit; however, at least one of the front-wheel brake mechanism and the rear-wheel brake mechanism may be provided in multiple units. Alternatively, one of the front-wheel brake mechanism and the rear-wheel brake mechanism may not be provided.

A configuration, operation, and the like, which will be described below, constitute merely one example, and the hydraulic pressure control unit according to the present invention is not limited to a case with such a configuration, such operation, and the like.

The same or similar description will appropriately be simplified or will not be made below. In the drawings, the same or similar members or portions will not be denoted by a reference sign or will be denoted by the same reference sign. A detailed structure will appropriately be illustrated in a simplified manner or will not be illustrated.

<Configuration of Hydraulic Pressure Control Unit>

A description will herein be made on a configuration of a hydraulic pressure control unit5according to the embodiment of the present invention with reference toFIG. 1toFIG. 5.

The hydraulic pressure control unit5controls a braking force to brake each wheel of a motorcycle100. In this embodiment, the hydraulic pressure control unit5is used in a brake system10for the motorcycle100. The brake system10corresponds to an example of the vehicle behavior control system according to the present invention, and is a system that uses a hydraulic pressure of a brake fluid as the hydraulic fluid to control behavior of the motorcycle100by the braking force.

FIG. 1is a schematic view of a configuration of the motorcycle100on which the brake system10including the hydraulic pressure control unit5is mounted.FIG. 2is a schematic diagram of a configuration of the brake system10.

As illustrated inFIG. 1andFIG. 2, the brake system10is mounted on the motorcycle100. The motorcycle100includes: a trunk1; a handlebar2that is held by the trunk1in a freely turnable manner; a front wheel3that is held by the trunk1in the freely turnable manner with the handlebar2; and a rear wheel4that is held by the trunk1in a freely rotatable manner. The motorcycle100also includes a display device71that is a device visually showing information. The display device71corresponds to an example of a notification device that notifies a driver of the information. For example, a display or a lamp is used as the display device71.

The brake system10includes: a first brake operation section11; a front-wheel brake mechanism12that brakes the front wheel3in an interlocking manner with at least the first brake operation section11; a second brake operation section13; and a rear-wheel brake mechanism14that brakes the rear wheel4in the interlocking manner with at least the second brake operation section13. The brake system10also includes the hydraulic pressure control unit5, and a part of the front-wheel brake mechanism12and a part of the rear-wheel brake mechanism14are included in the hydraulic pressure control unit5. The hydraulic pressure control unit5is a unit that has a function of controlling the braking force to be applied to the front wheel3by the front-wheel brake mechanism12and the braking force to be applied to the rear wheel4by the rear-wheel brake mechanism14.

The first brake operation section11is provided on the handlebar2and is operated by the driver's hand. The first brake operation section11is a brake lever, for example. The second brake operation section13is provided in a lower portion of the trunk1and is operated by the driver's foot. The second brake operation section13is a brake pedal, for example.

Each of the front-wheel brake mechanism12and the rear-wheel brake mechanism14includes: a master cylinder21in which a piston (not illustrated) is installed; a reservoir22that is attached to the master cylinder21; a brake caliper23that is held by the trunk1and has a brake pad (not illustrated); a wheel cylinder24that is provided in the brake caliper23; a primary channel25through which a brake fluid in the master cylinder21is delivered to the wheel cylinder24; a secondary channel26through which the brake fluid in the wheel cylinder24is released; and a supply channel27through which the brake fluid in the master cylinder21is supplied to the secondary channel26.

An inlet valve (EV)31is provided in the primary channel25. The secondary channel26bypasses a portion of the primary channel25between the wheel cylinder24side and the master cylinder21side from the inlet valve31. The secondary channel26is sequentially provided with an outlet valve (AV)32, an accumulator33, and a pump34from an upstream side. Between an end of the primary channel25on the master cylinder21side and a portion thereof to which a downstream end of the secondary channel26is connected, a first valve (USV)35is provided. The supply channel27communicates between the master cylinder21and a suction side of the pump34in the secondary channel26. A second valve (HSV)36is provided in the supply channel27.

The inlet valve31is an electromagnetic valve that is opened in an unenergized state and closed in an energized state, for example. The outlet valve32is an electromagnetic valve that is closed in an unenergized state and opened in an energized state, for example. The first valve35is an electromagnetic valve that is opened in an unenergized state and is closed in an energized state, for example. The second valve36is an electromagnetic valve that is closed in an unenergized state and is opened in an energized state, for example. As will be described below, each of the inlet valve31, the outlet valve32, the first valve35, and the second valve36corresponds to an example of an electromagnetic valve30in the hydraulic pressure control unit5.

The hydraulic pressure control unit5includes: a hydraulic pressure control mechanism51that includes the part of the front-wheel brake mechanism12and the part of the rear-wheel brake mechanism14described above; and a controller (ECU)52that controls operation of the hydraulic pressure control mechanism51.

More specifically, the hydraulic pressure control mechanism51of the hydraulic pressure control unit5includes: a base body51a; and components including the electromagnetic valves30, each of which is assembled in the base body51ato control the hydraulic pressure generated by the brake fluid in the brake system10.

For example, the base body51ahas a substantially rectangular-parallelepiped shape and is formed of a metallic material. In the base body51aof the hydraulic pressure control mechanism51, the primary channels25, the secondary channels26, and the supply channels27are formed, and the electromagnetic valves30(more specifically, the inlet valves31, the outlet valves32, the first valves35, and the second valves36), the accumulators33, and the pumps34are assembled as the components, each of which controls the hydraulic pressure generated by the brake fluid in the brake system10, in the base body51a. Operation of each of these components is controlled by the controller52in the hydraulic pressure control unit5as will be described later. The base body51amay be formed of one member or may be formed of multiple members. In the case where the base body51ais formed of multiple members, the components may separately be provided in the multiple members.

A description will hereinafter be made on a detailed description of the electromagnetic valve30such as the inlet valve31with reference toFIG. 3.

FIG. 3is a schematic cross-sectional view of an example of the electromagnetic valve30in the hydraulic pressure control unit5. More specifically, of the electromagnetic valves30provided in the hydraulic pressure control unit5, the electromagnetic valve30exemplified inFIG. 3is the electromagnetic valve30that is opened in the unenergized state and closed in the energized state.

As illustrated inFIG. 3, the electromagnetic valve30in the hydraulic pressure control unit5includes a case30a, an armature30b, a tappet30c, a coil30d, a core30e, a spring30f, a first channel30g, and a second channel30h, for example.

The armature30bcorresponds to a movable portion capable of reciprocating relative to the case30ain the case30a. For example, the armature30bhas a substantially cylindrical shape, is arranged in an internal space provided in the case30a, and can reciprocate along an axial direction of the armature30b. The tappet30cis fixed to the armature30band can integrally move with the armature30b. For example, the tappet30cis a solid rod member that has a circular cross-sectional shape, and is fitted and fixed to an inner circumferential section of the armature30b.

The coil30dis fixed to the case30aand generates a magnetic field by using supplied power. For example, the coil30dis provided in a manner to surround the internal space of the case30aalong a circumferential direction of the armature30b. The core30eis an iron core that is magnetized by the magnetic field generated by the coil30d, and has a substantially cylindrical shape, for example. In the internal space of the case30a, the core30eis coaxially arranged with the armature30b, and the tappet30cis inserted through an inner circumferential section of the core30e. When the core30eis magnetized, a magnetic force in a direction to approach the core30eacts on the armature30b.

The spring30furges the armature30bin a direction away from the core30e. For example, in the internal space of the case30a, the spring30fis provided in a manner to be held between an inner circumferential section of the case30aand an end surface of the armature30bon the core30eside.

The first channel30gand the second channel30hare formed in the case30aand each form a part of the primary channel25, the second channel26, or the supply channel27provided with the electromagnetic valve30. In the case30a, the first channel30gand the second channel30hare mutually connected via a space where a tip of the tappet30cis accommodated.

In a state where a current is not applied to the coil30d(that is, in the unenergized state), as indicated by a solid line inFIG. 3, the armature30bis held at a separated position from the core30eby an urging force of the spring30f. In this way, the first channel30gand the second channel30hare brought into a mutually communicating state (that is, a state where the electromagnetic valve30is opened).

Meanwhile, in a state where the current is applied to the coil30d(that is, in the energized state), as indicated by a two-dot chain line inFIG. 3, the armature30bis attracted to and held on the core30eside with the tappet30cby the magnetic force generated in the magnetized core30e. In this way, an opening at an end of the second channel30his closed by the tip of the tappet30c. As a result, the first channel30gand the second channel30hare brought into a mutually blocked state (that is, a state where the electromagnetic valve30is closed).

Here, the hydraulic pressure control unit5is provided with a current sensor40that detects a current value of a current flowing through the coil30dof the electromagnetic valve30. Note that the current sensor40may detect another physical quantity that can substantially be converted into the current value of the current flowing through the coil30dof the electromagnetic valve30. For example, as illustrated inFIG. 2, the current sensor40is provided for each of the electromagnetic valves30. A detection result of each of the current sensors40is output to the controller52and used for processing executed by the controller52.

More specifically, as the current sensors40, an inlet valve current sensor41, an outlet valve current sensor42, a first valve current sensor45, and a second valve current sensor46are respectively provided for the inlet valve31, the outlet valve32, the first valve35, and the second valve36. Just as described, each of the inlet valve current sensor41, the outlet valve current sensor42, the first valve current sensor45, and the second valve current sensor46corresponds to an example of the current sensor40in the hydraulic pressure control unit5.

A description will hereinafter be made on a detailed description of the current sensor40such as the inlet valve current sensor41with reference toFIG. 4.

FIG. 4is a schematic diagram of an example of the current sensor40in the hydraulic pressure control unit5.

As illustrated inFIG. 4, the current sensor40in the hydraulic pressure control unit5includes a shunt resistor40aand an operational amplifier40b, for example.

The shunt resistor40ais connected in series to the coil30d, which is connected to a power supply6, in the electromagnetic valve30. The power is supplied to the coil30dof the electromagnetic valve30from the power supply6such as a secondary battery. The operational amplifier40b, which is connected in parallel to the shunt resistor40a, differentially amplifies and outputs a voltage generated between both ends of the shunt resistor40a. The current sensor40detects the current value of the current flowing through the coil30dof the electromagnetic valve30on the basis of a resistance value of the shunt resistor40aand an output value of the operational amplifier40b, just as described.

More specifically, the controller52of the hydraulic pressure control unit5controls the operation of each of the above-described components that are assembled in the base body51aof the hydraulic pressure control mechanism51.

For example, the controller52is partially or entirely constructed of a microcomputer, a microprocessor unit, or the like. In addition, the controller52may partially or entirely be constructed of a member in which firmware or the like can be updated, or may partially or entirely be a program module or the like that is executed by a command from a CPU or the like, for example. The controller52may be provided as one unit or may be divided into multiple units, for example. Furthermore, the controller52may be attached to the base body51aor may be attached to a member other than the base body51a.

FIG. 5is a block diagram of an exemplary functional configuration of the controller52in the hydraulic pressure control unit5.

As illustrated inFIG. 5, the controller52includes an acquisition section52a, a control section52b, and a diagnosis section52c, for example.

The acquisition section52aacquires the information that is output from each of the sensors, a different controller from the controller52, or the like, and outputs the acquired information to the control section52band the diagnosis section52c. For example, the acquisition section52aacquires the information on a travel state of the motorcycle100, and outputs the information to the control section52b. In addition, for example, the acquisition section52aacquires the current value of the current flowing through the coil30dof the electromagnetic valve30from the current sensor40, and outputs the current value to the diagnosis section52c.

The control section52bcontrols the operation of each of the above-described components that are assembled in the base body51aof the hydraulic pressure control mechanism51. In this way, the control section52bcan control the braking force to be applied to the front wheel3by the front-wheel brake mechanism12and the braking force to be applied to the rear wheel4by the rear-wheel brake mechanism14. The control section52bcontrols the operation of each of the above components in accordance with the travel state of the motorcycle100, for example.

For example, in a normal state, that is, in a state where ABS operation, automatic braking operation, or the like, which will be described below, is not executed, the control section52bopens the inlet valve31, closes the outlet valve32, opens the first valve35, and closes the second valve36. When the first brake operation section11is operated in such a state, in the front-wheel brake mechanism12, the piston (not illustrated) in the master cylinder21is pressed to increase the hydraulic pressure of the brake fluid in the wheel cylinder24, the brake pad (not illustrated) of the brake caliper23is then pressed against a rotor3aof the front wheel3, and the braking force is thereby applied to the front wheel3. Meanwhile, when the second brake operation section13is operated, in the rear-wheel brake mechanism14, the piston (not illustrated) in the master cylinder21is pressed to increase the hydraulic pressure of the brake fluid in the wheel cylinder24, the brake pad (not illustrated) of the brake caliper23is then pressed against a rotor4aof the rear wheel4, and the braking force is thereby applied to the rear wheel4.

The ABS operation is operation that is executed when the wheel (more specifically, the front wheel3or the rear wheel4) is locked or possibly locked and that reduces the braking force applied to the wheel without relying on an operation of the brake operation section (more specifically, the first brake operation section11or the second brake operation section13) by the driver, for example. For example, in a state where the ABS operation is executed, the control section52bcloses the inlet valve31, opens the outlet valve32, opens the first valve35, and closes the second valve36. When the pump34is driven by the controller52in such a state, the hydraulic pressure of the brake fluid in the wheel cylinder24is reduced, and the braking force that is applied to the wheel is thereby reduced.

The automatic braking operation is operation that is executed when it becomes necessary to stabilize posture of the motorcycle100during turning of the motorcycle100or the like and that causes the generation of the braking force to be applied to the wheel (more specifically, the front wheel3or the rear wheel4) without relying on the operation of the brake operation section (more specifically, the first brake operation section11or the second brake operation section13) by the driver, for example. For example, in a state where the automatic braking operation is executed, the control section52bopens the inlet valve31, closes the outlet valve32, closes the first valve35, and opens the second valve36. When the pump34is driven by the controller52in such a state, the hydraulic pressure of the brake fluid in the wheel cylinder24is increased, and the braking force that is applied to the wheel is thereby generated.

The diagnosis section52cdiagnoses presence or absence of fixation of the electromagnetic valve30on the basis of the current value of the current flowing through the coil30dof the electromagnetic valve30. The fixation of the electromagnetic valve30means a state where the armature30bas the movable portion of the electromagnetic valve30cannot move. Such fixation of the electromagnetic valve30possibly occurs, for example, when a gas component of the brake fluid is evaporated in conjunction with a temperature increase of the brake fluid in the brake system10to a high temperature, when the brake fluid absorbs moisture, when a preservative in the brake fluid induces a chemical reaction, or the like.

More specifically, in a process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased at initiation of applying the current to the coil30d, the diagnosis section52cdetermines whether the current value has exhibited behavior of being temporarily reduced, and thereby diagnoses the presence or the absence of the fixation of the electromagnetic valve30.

In this embodiment, the controller52executes processing related to the diagnosis of the fixation of the electromagnetic valve30(processing primarily executed by the diagnosis section52c), so as to appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve30. The processing related to the diagnosis of the fixation of the electromagnetic valve30, just as described, will be described later in detail.

<Operation of Hydraulic Pressure Control Unit>

A description will herein be made on operation of the hydraulic pressure control unit5according to the embodiment of the present invention with reference toFIG. 6andFIG. 7.

FIG. 6is a flowchart of an example of a processing procedure that is executed by the controller52in the hydraulic pressure control unit5. More specifically, a control flow illustrated inFIG. 6corresponds to a processing flow that is related to the diagnosis of the fixation of the electromagnetic valve30among processing executed by the controller52, and is executed for the electromagnetic valves30in parallel. In addition, the control flow illustrated inFIG. 6is initiated after the brake system10is activated (in other words, after the motorcycle100starts driving), for example. Step S510and step S590inFIG. 6respectively correspond to initiation and termination of the control flow.

When the control flow illustrated inFIG. 6is initiated, in step S511, the diagnosis section52cdetermines whether the current starts being applied to the coil30dof the electromagnetic valve30. If it is determined that the current starts being applied to the coil30dof the electromagnetic valve30(step S511/YES), the processing proceeds to step S513. On the other hand, if it is determined that the current does not start being applied to the coil30dof the electromagnetic valve30(step S511/NO), the determination processing in step S511is repeated.

For example, the diagnosis section52cdetermines whether the current starts being applied to the coil30dof the electromagnetic valve30on the basis of the detection value of the current sensor40. More specifically, when the current starts being applied to the coil30dof the electromagnetic valve30, the current value of the current flowing through the coil30dstarts being increased toward a target current value. More specifically, the target current value is set to a current value with which the armature30bcan appropriately be held at a position that corresponds to the closed state of the electromagnetic valve30. Thus, the diagnosis section52ccan determine whether the current starts being applied to the coil30don the basis of behavior of the current value of the current flowing through the coil30dof the electromagnetic valve30.

In the present specification, time at which the current starts being applied to the coil30dof the electromagnetic valve30specifically means a period until the current value reaches the target current value after the current value of the current flowing through the coil30dstarts being increased in conjunction with the application of the current to the coil30d.

In step S513, the diagnosis section52cdetermines whether the increase in the current value of the current flowing through the coil30dof the electromagnetic valve30is finished. If it is determined that the increase in the current value of the current flowing through the coil30dof the electromagnetic valve30is finished (step S513/YES), the processing proceeds to step S515. On the other hand, if it is determined that the increase in the current value of the current flowing through the coil30dof the electromagnetic valve30is not finished (step S513/NO), the determination processing in step S513is repeated.

For example, the diagnosis section52cdetermines whether the increase in the current value of the current flowing through the coil30dof the electromagnetic valve30is finished on the basis of the detection value of the current sensor40. More specifically, the current value of the current flowing through the coil30dof the electromagnetic valve30is maintained at the target current value after being increased and reaching the target current value due to the application of the current to the coil30d. Thus, the diagnosis section52ccan determine whether the increase in the current value of the current flowing through the coil30dis finished on the basis of the behavior of the current value of the current flowing through the coil30dof the electromagnetic valve30.

In step S515, the diagnosis section52cdetermines whether behavior of the power supply6, which supplies the power to the coil30dof the electromagnetic valve30, has been abnormal in a process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased. If it is determined that the behavior of the power supply6has been abnormal (step S515/YES), the processing returns to step S511. On the other hand, if it is determined that the behavior of the power supply6has been normal (step S515/NO), the processing proceeds to step S517.

For example, the motorcycle100is provided with a sensor (not illustrated) that detects a state amount such as a voltage value of the power supply6. The diagnosis section52cdetermines whether the behavior of the power supply6has been abnormal (for example, whether the voltage value of the power supply6has been excessively unstable) on the basis of a detection result that is output from the sensor to the controller52. Note that, in the case where the different controller from the controller52outputs information indicative of whether the behavior of the power supply6has been abnormal to the controller52, the diagnosis section52cmay determine whether the behavior of the power supply6has been abnormal on the basis of such information output from the other controller.

In step S517, the diagnosis section52cdetermines the presence or the absence of the fixation of the electromagnetic valve30.

More specifically, in the process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased at the initiation of applying the current to the coil30d, the diagnosis section52cdetermines whether the current value has exhibited the behavior of being temporarily reduced, and thereby diagnoses the presence or the absence of the fixation of the electromagnetic valve30. At this time, if it is determined that the current value of the current flowing through the coil30dhas exhibited the behavior of being temporarily reduced, the diagnosis section52cdiagnoses that the fixation of the electromagnetic valve30does not occur.

FIG. 7is a schematic graph of an exemplary transition of the current value of the current flowing through the coil30dof the electromagnetic valve30in the hydraulic pressure control unit5at the initiation of applying the current to the coil30d. More specifically, inFIG. 7, the transition of the current value of the current flowing through the coil30dat the time when the fixation of the electromagnetic valve30does not occur is indicated by a solid line, and the transition of the current value of the current flowing through the coil30dat the time when the fixation of the electromagnetic valve30occurs is indicated by a broken line. In addition, inFIG. 7, a horizontal axis represents time t [ms], and a vertical axis represents a current value i [A].

In the case where the fixation of the electromagnetic valve30does not occur, in the electromagnetic valve30, the core30eis magnetized in conjunction with the application of the current to the coil30d. In this way, the magnetic force in the direction to approach the core30eacts on the armature30b, and the armature30bis attracted and moves to the core30eside with the tappet30c. At this time, in the magnetic field generated by the coil30d, the armature30bmoves relative to the magnetic field. As a result, a counter-electromotive force is generated in the coil30din a manner to weaken magnetic flux generated by the coil30d. Thus, as indicated by the solid line inFIG. 7, in the process in which the current flowing through the coil30dis increased, the current value exhibits the behavior of being temporarily reduced. For example,FIG. 7illustrates a situation where the current value of the current flowing through the coil30dstarts being reduced at time t1and the reduction of the current value is terminated at time t2.

Meanwhile, in the case where the fixation of the electromagnetic valve30occurs, in the electromagnetic valve30, the core30eis magnetized in conjunction with the application of the current to the coil30d. In this way, although the magnetic force in the direction to approach the core30eacts on the armature30b, the armature30bdoes not move to the core30eside. As a result, the counter-electromotive force, which is associated with the movement of the armature30b, is not generated in the coil30d. Thus, as indicated by the broken line inFIG. 7, in the process in which the current flowing through the coil30dis increased, the current value does not exhibit the behavior of being temporarily reduced.

As described above, in the process in which the current value of the current flowing through the coil30dis increased, the current value exhibits the behavior of being temporarily reduced in the case where the fixation of the electromagnetic valve30does not occur, and the current value does not exhibit the behavior of being temporarily reduced in the case where the fixation of the electromagnetic valve30occurs. Thus, in the process in which the current value of the current flowing through the coil30dis increased, it is determined whether the current value has exhibited the behavior of being temporarily reduced. In this way, the presence or the absence of the fixation of the electromagnetic valve30can be diagnosed.

From a perspective of appropriately diagnosing the presence or the absence of the fixation of the electromagnetic valve30, for example, in the case where a reduced amount of the current value is greater than a reference value at the time when the current value of the current flowing through the coil30dis continuously reduced, the diagnosis section52cpreferably determines that the current value has exhibited the behavior of being temporarily reduced, and preferably diagnoses that the fixation of the electromagnetic valve30does not occur. The above reference value is appropriately set to a value with which it is possible to appropriately determine whether the counter-electromotive force is generated in the coil30ddue to the movement of the armature30b. The above reference value is set on the basis of a specification of the electromagnetic valve30and a specification of the brake fluid in the brake system10, for example.

Note that the diagnosis section52cmay use a reduced amount of the current value of the current flowing through the coil30dper unit time as the above reduced amount, so as to determine whether the current value has exhibited the behavior of being temporarily reduced. Alternatively, the diagnosis section52cmay use the reduced amount of the current value in a period from time at which the current value of the current flowing through the coil30dstarts being reduced to time at which the reduction of the current value is terminated, so as to determine whether the current value has exhibited the behavior of being temporarily reduced.

Here, from a perspective of further appropriately diagnosing the presence or the absence of the fixation of the electromagnetic valve30, the diagnosis section52cmay vary the above reference value in accordance with a temperature.

For example, the diagnosis section52cvaries the above reference value in accordance with a temperature of the brake fluid in the brake system10. In such a case, for example, the motorcycle100is provided with a sensor (not illustrated) that detects the temperature of the brake fluid in the brake system10. The diagnosis section52cvaries the above reference value on the basis of a detection result that is output from the sensor to the controller52. More specifically, the diagnosis section52cincreases the reference value as the temperature of the brake fluid in the brake system10is increased. As the temperature of the brake fluid is increased, viscosity of the brake fluid is reduced, and thus a moving speed of the armature30btends to be increased. As a result, the counter-electromotive force, which is generated in the coil30din conjunction with the movement of the armature30b, tends to be increased. Thus, the reference value is increased as the temperature of the brake fluid is increased. In this way, it is possible to further appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve30.

Note that the diagnosis section52cmay vary the above reference value in accordance with another physical quantity (for example, a temperature of the electromagnetic valve30, or the like) that can substantially be converted to the temperature of the brake fluid in the brake system10. In such a case, for example, the motorcycle100is provided with a sensor (not illustrated) detecting the other physical quantity that can substantially be converted to the temperature of the brake fluid in the brake system10. The diagnosis section52cvaries the above reference value on the basis of a detection result that is output from the sensor to the controller52.

Next, in step S519, the diagnosis section52cdetermines whether such a diagnosis that the fixation of the electromagnetic valve30occurs has been made. If it is determined that such a diagnosis that the fixation of the electromagnetic valve30occurs has been made (step S519/YES), the processing proceeds to step S521. If it is determined that such a diagnosis that the fixation of the electromagnetic valve30occurs has not been made (step S519/NO), the processing returns to step S511.

In step S521, the controller52outputs an operation command to make the notification device notify the driver of a diagnosis result (more specifically, the diagnosis result indicating that it is diagnosed the fixation of the electromagnetic valve30occurs).

For example, in the case where it is diagnosed that the fixation of the electromagnetic valve30occurs, the controller52outputs an operation command to the display device71so as to make the display device71display the diagnosis result indicating that the occurrence of the fixation of the electromagnetic valve30is diagnosed. Then, the controller52makes the display device71display the diagnosis result. Note that, as the notification device, a different device (for example, a device that outputs sound, or the like) from the display device71may be used.

As described above, in the control flow illustrated inFIG. 6, in the case where it is determined YES in step S515, the processing does not proceed to step S517and returns to step S511. That is, in the case where it is determined that the behavior of the power supply6has been abnormal in the process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased at the initiation of applying the current to the coil30d, the fixation of the electromagnetic valve30is not diagnosed. The fixation of the electromagnetic valve30is diagnosed at the initiation of applying the current to the coil30din the next flow or onward. From the perspective of further appropriately diagnosing the presence or the absence of the fixation of the electromagnetic valve30, as described above, in the case where it is determined that the behavior of the power supply6, which supplies the power to the coil30dof the electromagnetic valve30, has been abnormal in the process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased at the initiation of applying the current to the coil30d, it is preferred that the diagnosis section52cdoes not validate the diagnosis result of the fixation of the electromagnetic valve30.

Note that step S515may be executed after step S517or step S519. In such a case, if it is determined YES in step S515, the processing does not proceed to step S521but returns to step S511. That is, in the case where it is determined that the behavior of the power supply6, which supplies the power to the coil30dof the electromagnetic valve30, has been abnormal in the process in which the current value of the current flowing through the coil30dis increased, the diagnosis result of the fixation of the electromagnetic valve30is not validated, and the diagnosis of the fixation of the electromagnetic valve30is made again.

The above description has been made on the example in which the diagnosis section52cdiagnoses the presence or the absence of the fixation of the electromagnetic valve30in the process in which the current value of the current flowing through the coil30dof the electromagnetic valve30at the initiation of applying the current to the coil30d. However, in addition to such processing, the diagnosis section52cmay also diagnose the presence or the absence of the fixation of the electromagnetic valve30in a process in which the current value of the current flowing through the coil30dof the electromagnetic valve30at the termination of applying the current to the coil30d. For example, at the termination of applying the current to the coil30dof the electromagnetic valve30, the current value of the current flowing through the coil30dis reduced from the target current value. Thus, the diagnosis section52cmay determine whether the current value has exhibited the behavior of being temporarily increased in the process in which the current value of the current flowing through the coil30dis reduced. In this way, the diagnosis section52cmay diagnose the presence or the absence of the fixation of the electromagnetic valve30. At this time, in the case where it is determined that the current value of the current flowing through the coil30dhas exhibited the behavior of being temporarily increased, the diagnosis section52cdiagnoses that the fixation of the electromagnetic valve30does not occur.

In addition, the above description has been made on the example in which the control flow illustrated inFIG. 6is executed in parallel for all the electromagnetic valves30and the diagnosis of the fixation is made for each of the electromagnetic valves30. However, the fixation of at least one of the electromagnetic valves30in the hydraulic pressure control unit5may be diagnosed. In such a case, the current sensor40is provided only for the at least one electromagnetic valve30that is subjected to the diagnosis of the fixation, for example.

<Effects of Hydraulic Pressure Control Unit>

A description will be made on effects of the hydraulic pressure control unit5according to the embodiment of the present invention.

In the hydraulic pressure control unit5, in the process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased at the initiation of applying the current to the coil30d, the diagnosis section52cdetermines whether the current value has exhibited the behavior of being temporarily reduced, and thereby diagnoses the presence or the absence of the fixation of the electromagnetic valve30. As described above, in the process in which the current value of the current flowing through the coil30dis increased, the current value exhibits the behavior of being temporarily reduced in the case where the fixation of the electromagnetic valve30does not occur, and the current value does not exhibit the behavior of being temporarily reduced in the case where the fixation of the electromagnetic valve30occurs. Thus, in the process in which the current value of the current flowing through the coil30dis increased, it is determined whether the current value has exhibited the behavior of being temporarily reduced. In this way, the presence or the absence of the fixation of the electromagnetic valve30can be diagnosed.

Furthermore, according to the processing to diagnose the presence or the absence of the fixation of the above electromagnetic valve30by the diagnosis section52c, it is possible to diagnose the presence or the absence of the fixation of the above electromagnetic valve30without relying on change in a parameter (for example, the temperature of the brake fluid in the brake system10, or the like) that has an influence on the current value of the current flowing through the coil30dof the electromagnetic valve30. In this way, for example, compared to a case where the presence or the absence of the fixture of the electromagnetic valve30is diagnosed on the basis of a degree of deviation of the detected value of the current value of the current, which flows through the coil30d, from a value that is set in advance as an assumed current value when the fixation of the electromagnetic valve30does not occur, it is possible to appropriately diagnose the presence or the absence of the fixture of the electromagnetic valve30. Therefore, according to the processing to diagnose the presence or the absence of the fixation of the above electromagnetic valve30by the diagnosis section52c, it is possible to appropriately diagnose the presence or the absence of the fixture of the electromagnetic valve30.

Preferably, in the hydraulic pressure control unit5, in the case where the reduced amount of the current value is greater than the reference value at the time when the current value of the current flowing through the coil30dof the electromagnetic valve30is continuously reduced, it is determined that the current value has exhibited the behavior of being temporarily reduced, and it is diagnosed that the fixation of the electromagnetic valve30does not occur. Thus, when the reference value is appropriately set on the basis of the specifications of the electromagnetic valve30and the brake fluid, for example, it is possible to further appropriately diagnose whether the above current value has exhibited the behavior of being temporarily reduced in conjunction with the movement of the armature30bof the electromagnetic valve30. Therefore, it is possible to further appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve30.

Preferably, in the hydraulic pressure control unit5, the diagnosis section52cvaries the above reference value in accordance with the temperature. Thus, when the above reference value is varied in accordance with the temperature of the brake fluid in the brake system10, for example, the reference value can appropriately be set in accordance with a change in the viscosity of the brake fluid. As a result, it is possible to further appropriately determine whether the above current value has exhibited the behavior of being temporarily reduced in conjunction with the movement of the armature30bof the electromagnetic valve30. Therefore, it is possible to further appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve30.

Preferably, in the hydraulic pressure control unit5, in the case where it is determined that the behavior of the power supply6, which supplies the power to the coil30dof the electromagnetic valve30, has been abnormal in the process in which the current value of the current flowing through the coil30dof the electromagnetic valve30is increased at the initiation of applying the current to the coil30d, the diagnosis section52cdoes not validate the diagnosis result of the fixation of the electromagnetic valve30. In this way, it is possible to prevent erroneous diagnosis of the presence or the absence of the fixation of the electromagnetic valve30, which is caused by the abnormal behavior of the power supply6. For example, it is possible to prevent such diagnosis that the fixation of the electromagnetic valve30does not occur in the case where the fixation of the electromagnetic valve30occurs and the current value of the current flowing through the coil30dexhibits the behavior of being temporarily reduced due to the excessively unstable voltage value of the power supply6. Therefore, it is possible to further appropriately diagnose the presence or the absence of the fixation of the electromagnetic valve30.

Preferably, in the hydraulic pressure control unit5, in the case where it is diagnosed that the fixation of the electromagnetic valve30occurs, the controller52outputs the operation command to make the notification device notify the driver of the diagnosis result. In this way, when the fixation of the electromagnetic valve30occurs, it is possible to notify the driver of such fixation and thus to urge the driver to repair the motorcycle100, for example.

Preferably, the hydraulic pressure control unit5is used for the vehicle behavior control system (for example, the brake system10) of the motorcycle100. Here, a distance between the channel of the brake fluid and a drive source such as an engine tends to be shorter in the motorcycle100than in another vehicle. For this reason, the brake fluid is likely to be heated and reach the high temperature by heat that is generated by the drive source such as the engine. Thus, the gas component of the brake fluid is likely to be vaporized. Accordingly, particularly in the motorcycle100, the fixation of the electromagnetic valve30is likely to occur. Thus, when the hydraulic pressure control unit5is used for the vehicle behavior control system of such a motorcycle100, it is possible to effectively use such an effect that the presence or the absence of the fixation of the electromagnetic valve30can appropriately be diagnosed.

The present invention is not limited to each of the embodiments. For example, all or parts of the embodiments may be combined, or only a part of each of the embodiments may be implemented. In addition, an order of the steps may be switched, for example.