JP2015010630A - Pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire an actual characteristic to be the actual relationship between a voltage applied to a coil and a current flowing in the coil, while suppressing increase in servo pressure.SOLUTION: A decompression linear valve is provided between a control pressure chamber and a low-pressure source, and a pressure increase linear valve is provided between the control pressure chamber and a high-pressure source. When an actual characteristic about the coil of the decompression linear valve is acquired, a maximum current Ix, at which a poppet valve part does not become narrow, is used. Consequently, even when liquid pressure is supplied from the high-pressure source to the control pressure chamber by causing leakage of the pressure increase linear valve or the like, the liquid pressure of the control pressure chamber can be prevented from increasing, and thus servo pressure can be prevented from increasing.

Description

  The present invention relates to a pressure control device that controls a pressure of a device to be controlled by controlling a solenoid valve based on actual characteristics.

Patent Document 1 describes a hydraulic control device that controls the hydraulic pressure of a clutch or the like of a hydraulically operated transmission for a vehicle. In this hydraulic pressure control device, the current is controlled by controlling the voltage applied to the linear solenoid to control the hydraulic pressure of the clutch and the like.
Further, a resistance value, which is a value obtained by dividing the voltage applied to the linear solenoid by the current, is acquired in a non-operating state of the linear solenoid. As a result, it is possible to satisfactorily suppress a decrease in hydraulic pressure control accuracy caused by a change in resistance value due to a temperature change.

JP-A-9-280411

  An object of the present invention is to improve a pressure control device, for example, to obtain actual characteristics more appropriately.

Means and effects for solving the problem

In the pressure control device according to the present invention, the actual characteristic that is the actual relationship between the voltage applied to the coil and the flowing current is obtained after the operation of the normally open solenoid valve and before switching to the closed state.
When the solenoid valve is switched from the open state to the closed state, a sound may be generated. In order to obtain the actual characteristics with high accuracy, it is desirable to apply a large current or voltage.
On the other hand, in the pressure control device according to the present invention, since the actual characteristics are acquired after the solenoid valve is actuated and before switching to the closed state, the actual characteristics are accurately avoided while avoiding the generation of sound. Can be acquired.

Patentable invention

  Hereinafter, the invention recognized as being capable of being claimed in the present application, or features of the invention will be described.

(1) An actual characteristic acquisition device that acquires an actual characteristic that is an actual relationship between a voltage applied to the coil and a flowing current with respect to a normally open solenoid valve that is switched from an open state to a closed state by supplying a current to the coil. .
In the actual characteristic acquisition device described in this section, the actual characteristic of the coil of the normally open solenoid valve is acquired. The normally open solenoid valve is provided between the control target device and the low pressure source, and may be used as a pressure reduction control valve for controlling the pressure of the control target device to be reduced.
Even if the actual characteristics are obtained by acquiring the current that actually flows through the coil with the set voltage applied to the coil, the voltage actually applied to the coil can be acquired while the set current is supplied to the coil. You may acquire by. The same applies to the following items unless otherwise specified.
(2) The actual characteristic acquisition device according to item (1), further including a pre-switching acquisition unit that acquires the actual characteristic until the electromagnetic valve is switched from the open state to the closed state.
(3) In the state where the movable member of the electromagnetic valve is in an intermediate position between the backward end and the forward end, the intermediate time acquisition unit that acquires the actual characteristic is included in the item (1) or (2) Real characteristic acquisition device.
In the actual characteristic acquisition device described in this section, after the movement of the movable member is started, the actual characteristic is acquired in a state where the movement is not completed. Examples of the movable member include a valve element, a plunger that applies a driving force to the valve element (sometimes provided integrally with the valve element), a spool, and the like.
When the solenoid valve includes a poppet valve part with a valve element and a valve seat, actual characteristics are acquired from the start of approach to the valve seat until contact (not included in contact). Is done.
(4) The actual characteristic acquisition device according to any one of (1) to (3), wherein the actual characteristic is acquired in a state where a current flowing through the coil is larger than a set current.
The set current can be, for example, a current required for starting the movement of the plunger of the solenoid valve. The current required for starting movement may be determined by a set load of a spring provided in the solenoid valve.
The actual characteristic can be acquired in a state where the current I flowing through the coil is larger than the set current Is and smaller than the current Iopen necessary for switching to the closed state (Is <I <Iopen). . For example, the actual characteristic can be acquired (k <n) in a state where a current of {(Iopen−Is) · (k / n) + Is} is supplied.
(5) A maximum opening holding time acquisition unit that acquires the actual characteristics in a state where the opening of the solenoid valve is not smaller than the set opening by a maximum opening of the solenoid valve. ) The actual characteristic acquisition device according to any one of the items.
It can be considered that the opening degree of the solenoid valve is determined by the minimum value of the opening area and the channel cross-sectional area of the fixed throttle part and the variable throttle part. When the opening area of the variable restrictor is greater than or equal to the cross-sectional area of the fixed restrictor, the opening of the solenoid valve is determined by the fixed restrictor and is constant at the maximum opening. On the other hand, when the opening area of the variable restrictor is smaller than the cross-sectional area of the fixed restrictor, the opening of the solenoid valve is determined by the variable restrictor and is smaller than the maximum opening. A state in which the opening of the solenoid valve is determined by the fixed throttle is referred to as a “state in which the variable throttle does not become a throttle”, and a state determined by the variable throttle (for example, the opening area of the variable throttle is the channel cross-sectional area of the fixed throttle. The smaller state) can be referred to as “a state in which the variable aperture portion becomes an aperture”.
In the actual characteristic acquisition device described in this section, a state in which the opening degree of the electromagnetic valve is determined by the fixed throttle part (a state in which the opening degree is the maximum opening degree), or a state in which the opening degree of the electromagnetic valve is determined by the variable throttle part The actual characteristic is acquired in a state where the difference between the opening of the variable throttle portion and the maximum opening is smaller than the set value.
The fixed restrictor is configured by an inflow port, an outflow port, and the like of a solenoid valve. The flow passage cross-sectional area of the fixed restricting portion refers to the cross-sectional area of the portion where the restricting effect of the fixed restricting portion is exerted, for example, the cross-sectional area of the portion having the smallest flow cross-sectional area such as the inflow port and the outflow port. . Further, the flow passage cross-sectional area may correspond to the opening area of the port opening.
Further, the variable restricting portion includes a poppet valve portion (including a valve element and a valve seat), a spool valve portion, and the like.
(6) The solenoid valve includes a fixed throttle portion and a variable throttle portion,
The actual characteristic acquisition device acquires the actual characteristic using the maximum value of the current supplied to the coil when the opening area of the variable restrictor is equal to or larger than the flow passage cross-sectional area of the fixed restrictor. The actual characteristic acquisition device described in (5).
When the opening degree of the solenoid valve is the maximum opening degree, the maximum value of the current supplied is the current required to start moving the movable member of the solenoid valve and the current required to switch the solenoid valve to the closed state. And is close to the current required to switch to the closed state.
(7) In a state where the differential pressure between the high pressure side and the low pressure side of the solenoid valve is constant, the actual characteristic is obtained in a state where the flow rate of the fluid flowing through the solenoid valve is not smaller than the maximum flow rate determined by the differential pressure. The actual characteristic acquisition device according to any one of items (1) to (6), further including an acquisition unit for acquiring the maximum flow rate when acquiring.
When the differential pressure between the high pressure side and the low pressure side is constant, the flow rate of the fluid flowing through the solenoid valve is larger when the opening is large than when it is small, and when the opening is constant, the differential pressure is large. Is usually larger than small. For this reason, the flow rate of the fluid flowing through the electromagnetic valve is determined by the differential pressure and the opening, and the maximum flow rate of the electromagnetic valve is determined by the differential pressure and the flow passage cross-sectional area in the fixed throttle portion.
In a state where the differential pressure is constant, when the opening degree of the electromagnetic valve becomes smaller than the opening degree determined by the flow passage cross-sectional area of the fixed throttle portion, the flow rate flowing through the electromagnetic valve becomes smaller than the maximum flow rate. In the actual characteristic acquisition device described in this section, the actual characteristic is acquired in a state where the difference from the maximum flow rate is smaller than the set flow rate.
(8) The acquisition unit at the time of holding the maximum flow rate acquires the actual characteristic using the maximum value of the current supplied when the flow rate of the fluid flowing through the solenoid valve is the maximum flow rate of the solenoid valve. The actual characteristic acquisition device according to item (7).
The maximum current is greater than the midpoint between the current at the start of movement of the plunger and the current at the time of switching to the closed state.
(9) The solenoid valve includes a fixed throttle portion and a variable throttle portion,
The actual characteristic acquisition device has a range in which the flow rate of the fluid flowing through the electromagnetic valve is determined by the fixed throttle unit, and the flow rate determined by the variable throttle unit and the flow rate determined by the fixed throttle unit. Any one of the items (1) to (8), wherein the actual characteristic is obtained using the maximum value of the current supplied to the coil in a range including a range in which the absolute value of the difference is smaller than a set value. The actual characteristic acquisition apparatus as described in one.
The set value can be a value near zero.
(10) When the actual characteristic acquisition device assumes that the temperature of the coil is equal to or lower than a set temperature, the current is larger than the current required to start moving the movable member of the solenoid valve, and the solenoid valve is closed. The actual characteristic acquisition device according to any one of items (1) to (9), wherein the actual characteristic is acquired in a state where a current smaller than a current required for switching to is supplied.
(11) The actual characteristic acquisition device includes a learning voltage application acquisition unit that acquires the characteristic by applying a learning voltage to the coil of the solenoid valve,
When the learning voltage application acquisition unit is in a predetermined state before the solenoid valve is switched from the open state to the closed state, and the current flowing in the coil and the coil temperature is lower than a set temperature Any one of the items (1) to (10) includes a learning voltage determination unit that determines the learning voltage based on a low-temperature characteristic that is a relationship between a voltage applied to the coil and a current flowing through the coil. The actual characteristic acquisition device described in 1.
The characteristic is that when the coil temperature is high, the voltage for the same current is higher than when the coil temperature is low. Therefore, for example, when the learning voltage is determined based on the maximum current in the range where the flow rate does not decrease and the characteristics at high temperature, and the actual temperature of the coil is low, the maximum in the range where the flow rate does not decrease A current larger than the current may be supplied, and the flow rate may decrease when the characteristics are acquired. On the other hand, when the learning voltage is determined based on the low temperature characteristics, the flow rate does not decrease even if the actual coil temperature is high or low.
The low temperature characteristics can be stored in advance in the storage unit.
(12) Any one of the items (1) to (11), wherein the electromagnetic valve is a pressure reduction control valve that is provided between the control target device and a low pressure source and controls the pressure of the control target device to be reduced. The actual characteristic acquisition device described in 1.

(13) In an electromagnetic valve that includes a fixed throttle portion and a variable throttle portion, the opening area of the variable throttle portion is reduced by supplying current to the coil, and is switched from an open state to a closed state. A throttle characteristic is obtained which is a relationship between a differential pressure between the pressure side and the low pressure side and a current required to make an opening area of the variable throttle part smaller than a flow path cross-sectional area of the fixed throttle part. Electromagnetic valve throttle characteristic acquisition device.
The set value can also be set to zero.
The technical feature described in any one of the items (1) to (12) can be adopted in the electromagnetic valve throttle characteristic acquisition device.

(14) an actual characteristic acquisition unit that acquires an actual characteristic that is an actual relationship between the voltage applied to the coil of the normally open solenoid valve and the current flowing through the coil;
A pressure including a current control unit that controls the pressure of the device to be controlled by controlling the current by controlling the voltage applied to the coil of the solenoid valve based on the actual characteristic acquired by the actual characteristic acquisition unit; A control device,
The actual characteristic acquisition unit includes a pre-switching acquisition unit that acquires the actual characteristic in a state after the movement of the movable member is started in the open state until the actual characteristic acquisition unit is switched to the closed state. A pressure control device.
“The state until the movable member is moved to the closed state after the movement of the movable member is started in the open state of the electromagnetic valve” includes “when the movable member of the electromagnetic valve is stationary at the backward end position”, “closed”. "State" is not included.
The pressure control device controls the fluid pressure of the device to be controlled, but the fluid pressure may be a hydraulic pressure or an atmospheric pressure.
Further, for example, when the pressure control device is applied to a brake fluid pressure control device, the final control target device is a brake cylinder of the brake, but a fluid pressure control mechanism that controls the fluid pressure supplied to the brake cylinder (For example, a regulator or the like to which a solenoid valve is connected corresponds) can be used as the control target device.
The technical characteristics described in any one of the items (1) to (13) can be employed in the actual characteristic acquisition unit described in this section.
(15) The electromagnetic valve is a pressure reduction control valve provided between the device to be controlled and a low pressure source,
The pressure control device includes a pressure increase control valve provided between the device to be controlled and a high pressure source,
The actual characteristic acquisition unit increases the supply current to the coil of the pressure-reducing control valve in a state where the differential pressure between the device to be controlled and the high-pressure source is kept constant by the control of the pressure-increasing control valve. Meanwhile, a current increase unit at the time of pressure increase that acquires the supply current at the time when the pressure of the device to be controlled increases, and using the supply current acquired by the current acquisition unit at the time of pressure increase, the actual characteristics The pressure control device according to item (14) to be acquired.
If the supply current at the time when the pressure of the control target device increases is used, the actual characteristic is acquired using the maximum value of the current supplied when the pressure of the control target device does not increase in the differential pressure. be able to. As a result, when actual characteristics are acquired, the pressure of the control target device can be made difficult to increase.
The fluid of the high-pressure source reaches the low-pressure source through the pressure-increasing control valve, the control target device, and the pressure-reducing control valve, but due to the pressure-increasing control valve, the pressure-reducing control valve, and the flow path resistance in the fluid passage connecting them. In some cases, the pressure of the device to be controlled increases. The pressure of the control target device increases as the flow rate of the fluid flowing out to the low pressure source via the pressure reduction control valve decreases, and the pressure of the fluid supplied to the control target device from the high pressure source via the pressure increase control valve increases. Get higher.
Based on the above circumstances, when the flow rate of the fluid of the high-pressure source supplied through the pressure-increasing linear valve is constant and the supply current to the pressure-reducing linear valve is changed, the pressure of the control target device increases It can be seen that the opening degree of the pressure reducing linear valve is reduced, that is, the flow rate of the fluid flowing out from the pressure reducing linear valve to the low pressure source is reduced.
The “time when the pressure of the control target device increases” means at least one time point when the pressure increases more than a set value and when the pressure increase gradient becomes larger than the set gradient.
(16) The pressure control device
a regulator comprising: (a) a control piston; (b) a control pressure chamber provided behind the control piston; and (c) a servo chamber provided in front of the control piston;
A pressure increase control valve provided between the control pressure chamber and the high pressure source,
The electromagnetic valve is a pressure reducing control valve provided between the control pressure chamber and a low pressure source;
The current control unit includes a servo pressure control unit that controls a pressure of the servo chamber by controlling a supply current to each of the coil of the pressure increase control valve and the coil of the pressure reduction control valve;
The actual characteristic acquisition unit
A servo pressure sensor for detecting the pressure in the servo chamber;
The pressure reduction when the detected value of the servo pressure sensor increases while increasing the current supplied to the coil of the pressure reducing control valve while the current supplied to the coil of the pressure increasing control valve is kept constant A detection value increase current acquisition unit for acquiring a current flowing in the coil of the control valve;
A temperature correction coefficient acquisition unit that acquires a temperature correction coefficient as the actual characteristic using the current value acquired by the current acquisition unit when the detection value increases, according to (14) or (15) Pressure control device.
“When the detection value increases” means at least one of the case where the detection value increases by a set value or more and the case where the increase gradient of the detection value becomes larger than the set gradient.
It can be considered that the regulator corresponds to the control target device, or that the control pressure chamber or the servo chamber corresponds to the control target device.
(17) Learning voltage determination for determining a learning voltage that is a voltage applied to the coil used when acquiring an actual characteristic that is an actual relationship between a voltage applied to the coil of the solenoid valve and a current flowing through the coil. A device,
The supply current to the coil when the pressure on at least one of the high pressure side and the low pressure side of the solenoid valve changes while increasing the supply current to the coil of the solenoid valve, and the high pressure side and the low pressure side A multiple pair acquisition unit for acquiring a plurality of pairs in association with the differential pressure with
An intercept current acquisition unit that acquires a supply current to the coil when the differential pressure is 0 based on the differential pressure and the supply current of the multiple pairs acquired by the multiple-pair acquisition unit;
Based on the supply current acquired by the intercept current acquisition unit and the low temperature characteristics that are the relationship between the voltage applied to the coil and the flowing current when the temperature of the coil stored in advance is equal to or lower than a preset temperature A learning voltage determination device comprising: a low temperature characteristic correspondence acquisition unit that acquires the learning applied voltage.
The learning voltage determination device may be provided in the pressure control device or in an external device different from the pressure control device. When the pressure control device is provided in a vehicle, the external device may be a computer provided in a factory or the like.
“When the pressure of at least one of the high-pressure side and the low-pressure side changes” means at least one of a case where the pressure changes by a set value or more and a case where the pressure change gradient changes by a set gradient or more.
The technical characteristics described in any one of the items (1) to (16) can be employed in the learning voltage determination device described in this item.

1 is a circuit diagram of a hydraulic brake system including a pressure control device according to Embodiment 1 of the present invention. The pressure control device includes a learning applied voltage determination device and a diaphragm characteristic acquisition device. (a) It is sectional drawing of the pressure increase linear valve contained in the said hydraulic brake system. (b) It is a figure which shows the relationship between the differential pressure | voltage of the said pressure increase linear valve, and valve opening current. (a) It is sectional drawing of the pressure-reduction linear valve contained in the said hydraulic brake system. (b) It is a figure which shows the relationship between the differential pressure | voltage of the said pressure reduction linear valve, and valve opening current. It is a figure which shows the periphery of brake ECU of the said hydraulic brake system. (a) It is a circuit diagram of a control circuit included in the brake ECU. It is a figure which shows the change of the electric current in the control circuit of (b) and (a). (a) It is a figure which shows the characteristic of the said control circuit, and is the characteristic (standard characteristic, low temperature characteristic) memorize | stored in the memory | storage part of the said brake ECU. (b) It is a figure which shows the actual characteristic and standard characteristic of the said control circuit. It is a flowchart showing the linear valve control program memorize | stored in the memory | storage part of the said brake ECU. It is a flowchart showing the duty ratio determination program for learning memorize | stored in the said memory | storage part. It is a flowchart showing the temperature correction coefficient learning program memorize | stored in the said memory | storage part. (a) It is a figure which shows the relationship between the electric current supplied to the coil of the said pressure reduction linear valve, and flow volume. (b) It is a figure which shows the relationship between the differential pressure | voltage of the said pressure-reduction linear valve, valve opening current, the electric current which has a throttle effect, and a movement start electric current. (a) It is a figure which shows the relationship between the leakage amount of the said pressure increase linear valve, the magnitude | size of the opening of a pressure reduction linear valve, and the increase amount of a servo pressure. (b) It is sectional drawing which shows typically the regulator contained in the said hydraulic brake system. It is a figure which shows the supply current to the coil of a servo pressure at the time of determining the learning current, a pressure-increasing linear valve, and a pressure-reducing linear valve. It is a figure which shows the throttle characteristic of a pressure-reduction linear valve. It is a figure which shows the learning timing of a temperature correction coefficient, and the temperature change of a coil. It is a figure for demonstrating the subject of this invention. (a) It is a figure which shows the change of an actual electric current when the 1st control command value is an improper magnitude | size. (b) It is a figure which shows the dispersion | variation in the detected value of a current monitor, and the dispersion | variation in a characteristic. It is a block diagram which shows notionally the external apparatus which concerns on Example 2 of this invention. The external device includes a learning voltage determination device and an aperture characteristic acquisition device.

Embodiment of the Invention

Hereinafter, a hydraulic brake system including a pressure control device according to an embodiment of the present invention will be described in detail based on the drawings. The pressure control device controls fluid pressure as fluid pressure, and includes a learning voltage determination device and a solenoid valve throttle characteristic acquisition device.
The hydraulic brake system can be mounted on a hybrid vehicle, mounted on an electric vehicle or a fuel cell vehicle, or mounted on an internal combustion drive vehicle. When mounted on a hybrid vehicle, an electric vehicle, a fuel cell vehicle, etc., regenerative braking force is applied to the drive wheels, so regenerative cooperative control is performed, but in an internal combustion drive vehicle, regenerative cooperative control is performed. There is no. In any case, in the present hydraulic brake system, the brake force of the hydraulic brake is electrically controlled so as to have a desired magnitude.

<Configuration of hydraulic brake system>
As shown in FIG. 1, the hydraulic brake system includes (i) hydraulic pressures provided on the brake cylinders 6FL and 6FR of the hydraulic brakes 4FL and 4FR provided on the left and right front wheels 2FL and 2FR and on the left and right rear wheels 8RL and 8RR. Brake cylinders 12RL, 12RR of the brakes 10RL, 10RR, (ii) a hydraulic pressure generator 14 capable of supplying hydraulic pressure to the brake cylinders 6FL, 6FR, 12RL, 12RR, (iii) the brake cylinders 6FL, 6FR, 12RL, 12RR And a slip control valve device 16 provided between the hydraulic pressure generator 14 and the hydraulic pressure generator 14. The hydraulic pressure generating device 14, the slip control valve device 16 and the like are controlled by a brake ECU 20 (see FIG. 3) mainly composed of a computer.
[Slip control valve device]
The slip control valve device 16 includes a plurality of electromagnetic on-off valves 16a and 16r. The plurality of electromagnetic on-off valves 16a and 16r are individually opened and closed by controlling the current supplied to the coils 18a and 18r, and the hydraulic pressures of the brake cylinders 6FL, 6FR, 12RL, and 12RR are individually controlled. The electromagnetic on-off valves 16a and 16r can be referred to as slip control valves.

[Hydraulic pressure generator]
The hydraulic pressure generator 14 includes (i) a brake pedal 24 as a brake operation member, (ii) a master cylinder 26, (iii) a rear hydraulic pressure controller 28 that controls the hydraulic pressure in the rear chamber of the master cylinder 26, and the like. .
{Master cylinder}
The master cylinder 26 includes (a) a housing 30, (b) pressure pistons 32 and 34 and an input piston 36 and the like which are fitted in a cylinder bore formed in the housing 30 in series with each other in a liquid-tight and slidable manner. Including.
The fronts of the pressurizing pistons 32 and 34 are front pressurizing chambers 40 and 42, respectively. The front pressurizing chamber 40 is connected to the left and right front wheels 2FL, 2FR via the fluid passage 44, and the brake cylinders 6FL, 6FR of the 4FR are connected to the front pressurizing chamber 42 via the fluid passage 46. The brake cylinders 12RL and 12RR of the hydraulic brakes 10RL and 10RR of the wheels 8RL and 8RR are connected. These hydraulic brakes 4FL, 4FR, 10RL, and 10RR are operated by supplying hydraulic pressure to the brake cylinders 6FL, 6FR, 12RL, and 12RR, respectively, and suppress the rotation of the wheels 2FL, 2FR, 8RL, and 8RR. .
Hereinafter, in the present specification, when it is not necessary to distinguish wheel positions for hydraulic brakes, FL, FR, RL, and RR indicating wheel positions may be omitted.
Further, return springs are disposed between the pressure piston 32 and the housing 30 and between the two pressure pistons 32 and 34, respectively, and urge the pressure pistons 32 and 34 in the backward direction. When the pressurizing pistons 32 and 34 are in the retracted end position, the front pressurizing chambers 40 and 42 are communicated with the reservoir 52, respectively.

The pressurizing piston 34 includes (a) a front piston portion 56 provided at the front portion, (b) an intermediate piston portion 58 provided at the intermediate portion and projecting in the radial direction, and (c) provided at the rear portion. A rear small diameter portion 60 having a smaller diameter than the piston portion 58 is included. The front piston portion 56 and the intermediate piston portion 58 are respectively fitted to the housing 30 so as to be liquid-tight and slidable. The front piston portion 56 is a front pressurizing chamber 42 and the intermediate piston portion 58 is anterior. This is a chamber 62.
On the other hand, the housing 30 is provided with an annular inner peripheral projection 64, and the rear piston portion 58, that is, the rear small-diameter portion 60 is fitted in a liquid-tight and slidable manner. As a result, a back chamber 66 is formed between the intermediate piston portion 58 and the inner peripheral projection 64 behind the intermediate piston portion 58.
It may be considered that the front piston portion 56 and the intermediate piston portion 58 constitute a pressurizing piston, or the front piston portion 56 and the intermediate piston portion 58 constitute a pressurizing piston portion. it can.
The input piston 36 is positioned behind the pressure piston 34, and the space between the rear small diameter portion 60 and the input piston 36 is an input chamber 70. The brake pedal 24 is linked to the rear portion of the input piston 36 via an operating rod 72 or the like.

The annular chamber 62 and the input chamber 70 are connected by a connecting passage 80, and a communication control valve 82 is provided in the connecting passage 80. The communication control valve 82 is an electromagnetic on-off valve that is opened / closed by turning on / off the current supplied to the coil 82s, and is a normally closed valve that is closed when the current is off. A portion of the connection passage 80 closer to the annular chamber 62 than the communication control valve 82 is connected to the reservoir 52 by a reservoir passage 84, and a reservoir cutoff valve 86 is provided in the reservoir passage 84. The reservoir shut-off valve 86 is an electromagnetic on-off valve that is opened and closed by turning on and off the supply current to the coil 86s, and is a normally open valve that is open when it is off.
A stroke simulator 90 is connected to the portion of the connection passage 80 closer to the annular chamber 62 than the communication control valve 82 via the simulator passage 88. Since the stroke simulator 90 is connected to the input chamber 70 via the simulator passage 88 and the connection passage 80, the stroke simulator 90 is allowed to operate when the communication control valve 82 is open and is blocked when the communication control valve 82 is closed. Further, in the open state of the reservoir shut-off valve 86, the input chamber 70 is communicated with the reservoir 52, so that the operation of the stroke simulator 90 is prevented. Thus, the communication control valve 82 and the reservoir shut-off valve 86 also have a function as a simulator control valve.
Furthermore, a hydraulic pressure sensor 92 is provided in a portion closer to the annular chamber than a portion where the reservoir passage 84 of the connection passage 80 is connected. The hydraulic pressure sensor 92 detects the hydraulic pressure in the annular chamber 62 and the input chamber 70 in a state where the annular chamber 62 and the input chamber 70 are communicated with each other and are disconnected from the reservoir 52. Since the hydraulic pressure detected by the hydraulic pressure sensor 92 has a magnitude corresponding to the operating force of the brake pedal 24, it can be referred to as an operating force sensor or an operating hydraulic pressure sensor.

{Back hydraulic pressure control device}
A back hydraulic pressure control device 28 is connected to the back chamber 66.
The back hydraulic pressure control device 28 includes (a) a high pressure source 100, (b) a regulator 102, (c) a linear valve device 104, and the like.
The high-pressure source 100 includes a pump device including a pump 105 and a pump motor 106, and an accumulator 108 that stores hydraulic fluid discharged from the pump device in a pressurized state. The accumulator pressure, which is the hydraulic pressure of the hydraulic fluid stored in the accumulator 108, is detected by the accumulator pressure sensor 109, but the pump motor 106 is controlled so that the accumulator pressure is maintained within a predetermined setting range. The
The regulator 102 includes (d) a housing 110, and (e) a pilot piston 112 and a control piston 114 provided in the housing 110 in a direction parallel to the axis L and arranged in series with each other. A cylinder bore having a stepped shape is formed in the housing 110, and a pilot piston 112 and a control piston 114 are fitted in a liquid-tight and slidable manner on the large diameter portion, and connected to the high pressure source 100 on the small diameter portion. A high pressure chamber 116 is formed. A pilot pressure chamber 120 is provided between the pilot piston 112 and the housing 110, and a control pressure chamber 122 is provided behind the control piston 114. Between the control piston 114 and a step portion between the large diameter portion and the small diameter portion of the cylinder bore. Is the servo chamber 124. A high pressure supply valve 126 is provided between the servo chamber 124 and the high pressure chamber 116.

The high-pressure supply valve 126 is a normally closed valve. (F) The valve seat 130, (g) The valve element 132 provided so as to be able to be seated and separated from the valve seat 130, It includes a spring 136 and the like that applies an elastic force in the seating direction (retracting direction).
On the other hand, a fitting hole extending in parallel with the axis L is formed at the center of the main body of the control piston 114, and a portion extending in a direction (radial direction) orthogonal to the axis L is provided. A liquid passage 140 communicated with the liquid is formed. The liquid passage 140 is always in communication with a low pressure port connected to the reservoir 52.
A valve opening member 144 extending in parallel with the axis L is fitted into the fitting hole. An axial passage 146 is formed in the central portion of the valve opening member 144 in parallel with the axis L, the rear end opens to the liquid passage 140, and the front end faces the valve element 132. As a result, the front end portion of the valve opening member 144 facing the valve element 132 and the low pressure port are connected via the axial passage 146 and the liquid passage 140.
A spring 150 is provided between the valve opening member 144 and the housing 110 to urge the control piston 114 (having the valve opening member 144) in the backward direction.
Thus, the control piston 114 generally has a stepped shape, the rear of the large diameter portion is the control pressure chamber 122, and the front of the large diameter portion and the small diameter portion is the servo chamber 124.

The pilot pressure chamber 120 is connected to the liquid passage 46 via the pilot passage 152. Therefore, the hydraulic pressure of the front pressurizing chamber 42 of the master cylinder 26 acts on the pilot piston 112.
Further, the back chamber 66 of the master cylinder 26 is connected to the servo chamber 124 via a servo passage 154. Since the servo chamber 124 and the back chamber 66 are directly connected, the servo pressure Psrv that is the hydraulic pressure in the servo chamber 124 and the hydraulic pressure in the back chamber 66 are basically the same level. A servo pressure sensor 156 is provided in the servo passage 154 to detect the servo pressure Psrv.

Connected to the control pressure chamber 122 is a linear valve device 104 including a pressure increasing linear valve 160 as a pressure increasing control valve and a pressure reducing linear valve 162 as a pressure reducing control valve, and the hydraulic pressure in the control pressure chamber 122 is increased. The pressure linear valve 160 and the pressure reducing linear valve 162 are controlled. The pressure increasing linear valve 160 is a normally closed valve provided between the control pressure chamber 122 and the high pressure source 100, and the pressure reducing linear valve 162 is a normally open valve provided between the control pressure chamber 122 and the reservoir 52. It is a valve.
As shown in FIG. 2A, the pressure-increasing linear valve 160 includes a poppet valve portion 170 and a solenoid 172. The poppet valve portion 170 includes a valve seat 174 and a valve element 176, and the valve element 176 as a valve seat 174. The solenoid 172 includes a coil 180 and a plunger 182. When a current is supplied to the coil 180, an electromagnetic driving force Fd in a direction for separating the valve element 176 from the valve seat 174 is applied to the valve element 176 via the plunger 182. Further, the pressure-increasing linear valve 160 is provided in such a posture that a differential pressure acting force Fp corresponding to a hydraulic pressure difference between the high pressure source 100 and the control pressure chamber 122 acts in a direction in which the valve element 176 is separated from the valve seat 174.
Fp + Fd: Fs
The pressure-increasing linear valve 160 is switched from the closed state to the open state when the sum of the differential pressure acting force Fp and the electromagnetic driving force Fd becomes larger than the elastic force Fs of the spring 178, but the valve opening current Iopen and the differential pressure are switched. The relationship is shown in FIG.

As shown in FIG. 3A, the pressure-reducing linear valve 162 includes a poppet valve portion 186 and a solenoid 188. The poppet valve portion 186 includes a valve seat 190, a valve element 191, and a valve element 191 from the valve seat 190. The solenoid 188 includes a coil 194 and a plunger 195 that applies an electromagnetic driving force Fd to the valve element 191. When a current is supplied to the coil 194, an electromagnetic driving force Fd is applied by the plunger 195 so that the valve element 191 is seated on the valve seat 190. Further, the pressure difference between the control pressure chamber 122 and the reservoir 52 (if the fluid pressure in the reservoir 52 is considered to be almost atmospheric pressure, the pressure difference can be considered to be the same as the fluid pressure in the control pressure chamber 122). The corresponding differential pressure acting force Fp acts in a direction to separate the valve element 191 from the valve seat 190.
Fs + Fp: Fd
The pressure reducing linear valve 162 is switched from the open state to the closed state when the electromagnetic driving force Fd becomes larger than the sum of the differential pressure acting force Fp and the elastic force Fs of the spring 192. The valve opening current Iopen and the differential pressure are switched. FIG. 3B shows the relationship with (which can be considered as the hydraulic pressure in the control pressure chamber 122 as described above).

[Brake ECU]
As shown in FIG. 4, the brake ECU 20 is connected with the operation hydraulic pressure sensor 92, the accumulator pressure sensor 109, and the servo pressure sensor 156, and may be referred to as a stroke of the brake pedal 24 (hereinafter referred to as an operation stroke). ), A current monitor 202 for detecting a current flowing in the coil, and the like, and a pump motor 106, a coil 180 of the pressure increasing linear valve 160, a coil 194 of the pressure reducing linear valve 162, and the like are connected. .
The brake ECU 20 is mainly composed of a computer, and includes an execution unit 210, a storage unit 212, a control circuit 214, and the like. The storage unit 212 includes a circuit characteristic storage unit 220, a learning duty ratio determination program storage unit 222, a learning duty ratio storage unit 224, and the like, and stores a plurality of programs, tables, and the like. The control circuit 214 controls the current supplied to the coils 180 and 194 of the electromagnetic valves 160 and 162. In this embodiment, the control circuit 214 controls the current supplied to the coil 194 of the pressure-reducing linear valve 162. explain.
In addition, the hydraulic brake system is operated by electric energy supplied from the power source 250.

As shown in FIG. 5A, the control circuit 214 is configured by connecting a power source 250, a switching element 252, and a coil 194 in series. The resistor 254 is an equivalent description of the overall resistance of the control circuit 214 such as a resistor having a coil 194 and a switching element 252. The switching element 252 can be, for example, a transistor, and by controlling the duty, the voltage applied to the coil 194 is controlled, and the current flowing through the coil 194 is controlled. Since the voltage applied to the coil 194 is larger when the duty ratio is large than when it is small, the voltage is represented by the duty ratio in this embodiment.
In the control circuit of FIG.
u (t) = R · i (t) + L · di (t) / dt
Is established. u (t) is a voltage applied to the coil 194 by duty control of the switching element 252, and i (t) is a current flowing through the coil 194. L is the inductance of the coil 194, and R is the resistance value of the entire control circuit 214.
When the above equation is Laplace transformed (d / dt = s), the following equation is obtained.
I (s) = {1 / (L · s + R)} · U (s)
As shown in the above equation, the transfer function between the voltage (duty ratio) and the current is expressed by a first-order lag response equation. As shown in FIG. 5 (b), the current value increases with a delay with respect to the change of the duty ratio (transiently), and thereafter (steadily) with a constant magnitude determined by the duty ratio and the resistance value. Become.

On the other hand, the resistance value R of the coil 194 increases as the temperature increases, as shown in the following equation.
R (T) = R (T0) + γ (T−T0)
T is an actual temperature of the coil 194, T0 is a standard temperature (for example, but not limited to 25 ° C.), and γ is a positive coefficient. Therefore, as shown in FIG. 6 (a), the relationship between the current and the duty ratio is a relationship indicated by a solid line when the temperature is a standard temperature, and a relationship indicated by a two-dot chain line when the temperature is high. The relationship is shown by a one-dot chain line.

<Operation in hydraulic brake system>
[Outline]
When this hydraulic brake system is mounted on an electric vehicle, a hybrid vehicle or the like, regenerative cooperative control is performed in principle.
For example, when the brake pedal 24 is depressed by the driver, a braking request is issued. When the braking force corresponding to the braking request is satisfied by the regenerative braking force, the hydraulic brakes 4 and 10 are not operated.
The linear valve device 104 is not controlled and the regulator 102 is inactive. The back chamber 66 of the master cylinder 26 is communicated with the reservoir 52. In the master cylinder 26, the communication control valve 82 is open and the reservoir shut-off valve 86 is closed. As the brake pedal 24 advances, the input piston 36 is advanced relative to the pressurizing piston 34 and the stroke simulator 90 is activated. Further, since the area of the pressure receiving surface facing the annular chamber 62 of the intermediate piston portion 58 and the area of the pressure receiving surface facing the input chamber 70 of the rear small diameter portion 60 are the same, in the pressurizing piston 34, The forward force caused by the hydraulic pressure and the backward force caused by the hydraulic pressure in the annular chamber 62 are balanced. Therefore, in principle, the pressurizing piston 34 is not moved forward, and no hydraulic pressure is generated in the front pressurizing chambers 40 and 42.

On the other hand, when the braking force required by the driver is insufficient with the regenerative braking force, the hydraulic brakes 4 and 10 are operated.
In the regulator 102, when the control pressure Psi, which is the hydraulic pressure in the control pressure chamber 122, is increased by the control of the linear valve device 104, the control piston 114 is advanced. As a result, the servo pressure Psrv is increased and supplied to the back chamber 66.
In the master cylinder 26, the pressurizing piston 34 is advanced by the hydraulic pressure in the back chamber 66, the hydraulic pressure is generated in the front pressurizing chambers 40, 42, supplied to the brake cylinders 6, 12, and the hydraulic brake 4 , 10 are activated.
Thus, the hydraulic pressure of the brake cylinders 6 and 12 is controlled by the control of the linear valve device 104, and the hydraulic braking force and the regenerative braking force are controlled to satisfy the braking force required by the driver. .
When the hydraulic brake system is mounted on an internal combustion drive vehicle or when regenerative cooperative control is not performed, the linear valve device is configured so that the braking force requested by the driver is satisfied by the hydraulic braking force. 104 is controlled.

[Control of linear valve]
The pressure-increasing linear valve 160 and the pressure-decreasing linear valve 162 are each controlled by a linear valve control program represented by the flowchart of FIG.
In step 1 (hereinafter abbreviated as S1. The same applies to other steps), it is determined whether or not there is an operation request for the hydraulic brakes 4 and 10. If there is a brake operation request, in S2, the target hydraulic pressure in the front pressurizing chambers 40, 42 is determined according to the braking force requested by the driver, and the target servo pressure is determined. Then, target currents Irefa and Irefr that are target values of supply current to the coils 180 and 194 of the pressure-increasing linear valve 160 and the pressure-reducing linear valve 162 are determined so that the actual servo pressure approaches the target servo pressure. In S3, duty ratios Dza and Dzr are determined based on target currents Irefa and Irefr and actual characteristics acquired in advance for each of coils 180 and 194, and in S4, switching element 252 is set to duty ratio Dza. , Dzr.
In the regulator 102, there is a predetermined relationship between the control pressure Psi and the servo pressure Psrv, and the control pressure Psi and the servo pressure Psrv have a one-to-one correspondence. Hereinafter, in the present embodiment, the control of the supply current to the coil 194 of the pressure reducing linear valve 162 will be described on the assumption that the control pressure Psi and the servo pressure Psrv are substantially the same.

The target current Irefr for the coil 194 of the pressure-reducing linear valve 162 is determined to have a magnitude that can maintain the closed state even when the servo pressure Psrv reaches the target hydraulic pressure. Then, suppose that the duty ratio Dr is determined based on the target current Irefr and the standard characteristic indicated by the solid line in FIG. 6A stored in the circuit characteristic storage unit 220, thereby controlling the switching element 252. Assuming that The standard characteristic is a relationship between the current and the duty ratio when the temperature of the coil 194 is a standard temperature (for example, 25 ° C.). On the other hand, since the resistance value R of the control circuit 214 changes as the temperature changes as described above, the relationship between the characteristic current and the duty ratio also changes. Therefore, when the switching element 252 is controlled with the duty ratio Dr determined based on the standard characteristic indicated by the solid line in FIG. 6A and the target current Irefr, the actual temperature of the coil 194 is lower than the standard temperature. A current larger than the target current Irefr flows (Ia1> Irefr), and if the actual temperature is higher than the standard temperature, a current smaller than the target current Irefr flows (Ia2 <Irefr). For example, when a control command value is output for the first time to the coil 194 of the pressure-reducing linear valve 162, such as when the hydraulic brakes 4 and 10 are started, as indicated by the alternate long and short dash line in FIG. When the actual temperature of the coil 194 is high, the current flowing through the coil 194 is insufficient, and the hydraulic fluid in the control pressure chamber 122 may flow out to the reservoir 52 via the pressure reducing linear valve 162. On the other hand, as shown by the broken line, when the actual temperature of the coil 194 is low, an excessive current flows, so that overshoot causes abnormal noise or takes a long time to approach the target current. There is a problem such as need.
Therefore, in this embodiment, the duty ratio is determined based on the target current and the actual characteristics that are characteristics when the temperature of the coil 194 is the actual temperature, and the switching element 252 is controlled.

{About temperature correction coefficient}
As shown in FIG. 6 (b), the standard characteristics are as follows: D = αn · I + β
Can be expressed (straight line). The gradient αn is a gradient of the duty ratio with respect to the current when the temperature of the coil 194 is the standard temperature, and corresponds to the resistance value. The intercept β is a duty ratio when the current I is 0, and is the same even if the temperature of the coil 194 changes.
The temperature correction coefficient KT is a ratio (KT = α / αn) of the gradient α (= ΔDa / ΔIa) at the actual temperature to the gradient αn at the standard temperature described above.
The temperature correction coefficient KT is acquired whenever the hydraulic brakes 4 and 10 are in an inactive state and a predetermined learning interval elapses, that is, every time the learning timing is reached. At the learning timing, one actual measurement point Z represented by the actual voltage and current applied to the coil 194 is acquired. The voltage is represented by the duty ratio of the control actually performed on the switching element 252, and the current is actually detected by the current monitor 202. Then, based on the acquired actual measurement point Z (Dx0, Ixr) and standard characteristics (determined by αn and β), the temperature correction coefficient KT is determined as shown in the following equation.
KT = (Dx0−β) / (Ixr · αn)
The actual characteristic when the temperature of the coil 194 is an actual temperature is represented by a straight line passing through the actual measurement point Z and the intercept β, as shown in the following equation.
D = α ・ KT + β
α = αn · KT
As described above, the actual characteristic is determined based on the standard characteristic and the temperature correction coefficient. However, since the actual characteristic is determined by the temperature correction coefficient KT, the temperature correction coefficient KT can be the actual characteristic.
If the duty ratio Dr determined based on the target current Irefr and the standard characteristics is corrected using the temperature correction coefficient KT, the duty ratio D * determined based on the target current Irefr and the actual characteristics can be acquired.
D * = KT · (Dr−β) + β

"Throttle effect of poppet valve section 186"
As shown in FIG. 3, the pressure-reducing linear valve 162 includes a fixed throttle portion constituted by an inflow port 280, an outflow port 282, and the like, and a variable throttle portion constituted by a poppet valve portion 186 and the like. The opening (opening area) of the variable restrictor is equal to or greater than the cross-sectional area of the fixed restrictor (the minimum value of the cross-sectional area of the inflow port 280, outflow port 282, etc., hereinafter the same). In the meantime, the opening degree of the pressure-reducing linear valve 162 is at the maximum opening degree determined by the fixed throttle portion. On the other hand, when the opening area of the variable restrictor is smaller than the cross-sectional area of the fixed restrictor, the opening of the pressure reducing linear valve 162 is determined by the variable restrictor and is smaller than the maximum opening. The relative positional relationship of the valve element 191 with respect to the valve seat 190, that is, the opening degree of the poppet valve portion 186, is determined by the relationship between the differential pressure acting force Fp, the elastic force Fs of the spring 192, and the electromagnetic driving force Fd. When the differential pressure acting force Fp is constant, when the electromagnetic driving force Fd increases, the valve element 191 approaches the valve seat 190 and the opening degree decreases.
For example, when the hydraulic pressure difference between the high pressure side and the low pressure side is substantially constant (ΔP = ΔPa), as shown in FIGS. 10 (a) and 10 (b), the electromagnetic driving force Fd increases as the supply current increases. FIG. 3 (a) shows that when the pressure becomes larger than the sum of the differential pressure acting force Fp and the elastic force Fs of the spring 192 (is the set load of the spring 192 when the differential pressure is almost zero) (Is). As shown, the valve element 191 (plunger 195) as a movable member starts to move toward the valve seat 190. As the valve element 191 approaches the valve seat 190, the opening of the poppet valve portion 186 decreases. However, as long as the opening is equal to or larger than the flow passage cross-sectional area of the fixed throttle portion such as the inflow port 280, the pressure reducing linear valve The opening degree 162 is the maximum opening degree, and the flow rate is substantially constant (the flow rate is the maximum flow rate determined by the differential pressure). In this state, the poppet valve portion 186 is not throttled.

When the supply current to the coil 194 is increased and the opening area of the poppet valve portion 186 becomes smaller than the cross-sectional area of the flow path such as the inflow port 280, the opening degree of the pressure reducing linear valve 162 is reduced and the flow rate is reduced. When the flow rate starts to decrease (strictly speaking, when the flow rate becomes smaller than the set value), the supply current Ix is in a state where the flow rate of the pressure reducing linear valve 162 does not decrease (the opening degree of the pressure reducing linear valve 162 is fixed) The maximum value of the current supplied in a state determined by the part, or a state in which the poppet valve part 186 is not throttled).
Thereafter, as the current supplied to the coil 194 increases, the opening of the variable throttle portion decreases, the flow rate decreases, and the closed state is established (Iopen). The state in which the opening area of the variable restrictor is smaller than the cross-sectional area of the flow path of the fixed restrictor, and the state before switching to the closed state is a state in which the opening of the pressure reducing linear valve 162 is determined by the variable restrictor. In this state, the valve portion 186 becomes a throttle.
In FIG. 10B, lines representing the current Is that the valve element 191 starts to approach the valve seat 190, the maximum current value Ix that the poppet valve portion 186 does not restrict, and the valve opening current Iopen are shown for simplicity. Although described as being straight and parallel to each other, these lines are not necessarily parallel to each other.

"Determination of learning current and learning duty ratio used when acquiring temperature correction coefficient KT"
[1] The supply current to the coil 194 is preferably as large as possible.
The variation in the detection value of the current monitor 202 is usually almost constant regardless of the magnitude of the current. Therefore, as shown in FIG. 15 (b), when the current (duty ratio) supplied when acquiring the temperature correction coefficient KT is large, the variation in actual characteristics acquired is smaller than when it is small, The actual characteristics can be obtained with higher accuracy when the current is supplied. Therefore, when acquiring the temperature correction coefficient KT, a current larger than the current (Is) at the time of starting the operation of the pressure-reducing linear valve 162 (when the valve element 191 starts approaching the valve seat 190) is supplied. It is desirable (I> Is).
[2] The supply current to the coil 194 is preferably smaller than the valve opening current Iopen. This is because when the current equal to or greater than the valve opening current Iopen is supplied, the valve element 191 comes into contact with the valve seat 190 to generate a sound (Iopen> I).

[3] It is desirable that a current in a range where the poppet valve unit 186 does not become a throttle is supplied.
As shown in FIG. 11 (b), the pressure reducing linear valve 162 is provided between the control pressure chamber 122 and the reservoir 52, and the pressure increasing linear valve 160 is provided between the control pressure chamber 122 and the high pressure source 100. . When the pressure-increasing linear valve 160 and the pressure-decreasing linear valve 162 are in the open state, the hydraulic fluid that has flowed out from the high-pressure source 100 flows into the reservoir 52 through the control pressure chamber 122. In this case, the control pressure Psi is caused by the hydraulic pressure difference between the accumulator 108 and the reservoir 52, the throttling effect of the pressure-increasing linear valve 160 and the pressure-reducing linear valve 162, the flow path resistance of the liquid passage connecting them. May become higher than atmospheric pressure, and the servo pressure Psrv may also become higher than atmospheric pressure.
On the other hand, when no current is supplied to the coil 180 of the pressure-increasing linear valve 160, the pressure-increasing linear valve 160 is in a closed state, so the hydraulic fluid from the high-pressure source 100 is not supplied to the control pressure chamber 122, and the servo pressure Psrv. Seems to be at atmospheric pressure. However, the hydraulic fluid may be supplied from the high-pressure source 100 to the control pressure chamber 122 through the pressure-increasing linear valve 160 due to leakage or the like due to circumstances of the pressure-increasing linear valve 160 (for example, clogging of foreign matter). In this case, the servo pressure Psrv may increase when the pressure reducing linear valve 162 is switched to the closed state or when the poppet valve unit 186 is in the throttle state. Then, the hydraulic pressure in the back chamber 66 is increased, the pressurizing piston 34 is moved forward, the hydraulic pressure is generated in the front pressurizing chambers 40 and 42, and the hydraulic brakes 4 and 10 may be operated.
In the pressure-increasing linear valve 160, there is a case where leakage occurs not only from the beginning of actual characteristic learning but also from the middle.

As shown in FIG. 11 (a), the increase amount of the servo pressure Psrv may be determined by the amount of leakage of the pressure-increasing linear valve 160 and the throttle effect of the pressure-reducing linear valve 162 (in the case of being determined by the fixed throttle portion, the variable throttle portion). )). When the throttle effect of the pressure reducing linear valve 162 is the same, the increase amount of the servo pressure Psrv becomes larger when the leakage amount of the pressure increasing linear valve 160 is larger than when it is small, and the leakage amount of the pressure increasing linear valve 160 is larger. In the same case, when the throttle effect of the pressure reducing linear valve 162 is large (small opening area), it is larger than when it is small (large opening area).
In the state where the opening degree of the pressure-reducing linear valve 162 is maximum, the increase amount of the servo pressure Psrv is equal to or less than the allowable threshold value ΔPsth even if the leakage amount of the pressure-increasing linear valve 160 is large. Therefore, even if the servo pressure Psrv increases from the atmospheric pressure to the allowable threshold value ΔPsth and is supplied to the back chamber 66, it is considered that the pressurizing piston 34 does not advance by the return spring or the like. Further, even if the pressurizing piston 34 moves forward and hydraulic pressure is generated in the front pressurizing chambers 40 and 42 and the hydraulic brakes 4 and 10 are operated, it is considered that the driver does not feel uncomfortable. .
From the above circumstances, when acquiring the temperature correction coefficient KT, it is desirable to supply a current in a range (determined by the fixed throttle portion) in which the opening degree of the pressure reducing linear valve 162 is maintained at the maximum opening degree (I ≦ Ix). .

Based on the above [1] to [3], in this embodiment, when the temperature correction coefficient KT is acquired, the maximum value of the current supplied when the opening of the pressure reducing linear valve 162 is the maximum opening ( In the following, Ix is sometimes used.
The maximum current Ix is larger than the current Is at the start of movement of the plunger 195 and smaller than the valve opening current Iopen.
Is <Ix <Iopen
The maximum current Ix is usually larger than Iopen / 2 (Ix> Iopen / 2), and sometimes larger than {(Iopen + Is) / 2}. Thus, the maximum current Ix is a value that satisfies the requirements [1], [2], and [3].

[4] Acquisition of Learning Current The maximum current Ix0 when the differential pressure of the pressure reducing linear valve 162 is 0 is set as the learning current. The learning current Ix0 is acquired, for example, in a state where the temperature of the coil 194 is substantially the standard temperature in the vehicle factory before the vehicle is brought into a state where it can run.
The servo pressure Psrv is increased by the servo pressure sensor 156 while the supply current to the coil 194 is increased from the state where the servo pressure Psrv is controlled to P1 and P2, respectively, in a state where no current is supplied to the coil 194 of the pressure reducing linear valve 162. Is detected. Then, the currents (Ix1, Ix2) that actually flow through the coil 194 at the time when the servo pressure Psrv increases by the set value or more are acquired. The servo pressures P1 and P2 have different sizes, and the currents Ix1 and Ix2 that actually flow through the coil 194 also have different sizes.
The servo pressure Psrv is controlled by controlling the current supplied to the coil 180 of the pressure increasing linear valve 160. The state where the servo pressure Psrv is P1, P2 can be considered as the state where the differential pressure between the high pressure side and the low pressure side of the pressure reducing linear valve 162 is P1, P2.
As shown in FIG. 12, when the servo pressure Psrv is constant at P1 and P2, the servo pressure Psrv should not change when the opening degree of the pressure reducing linear valve 162 is constant at the maximum opening degree. On the other hand, when the opening degree of the pressure reducing linear valve 162 becomes smaller than the maximum opening degree and the flow rate becomes smaller than the maximum flow rate determined by the differential pressure, the servo pressure Psrv increases.
In other words, when the servo pressure Psrv increases by the set value Δp or more, it can be assumed that the opening degree of the pressure-reducing linear valve 162 is decreased and the flow rate is decreased. Can be obtained as the maximum current Ix.

In this way, a plurality of actual measurement points Y represented by the differential pressure between the high pressure side and the low pressure side of the pressure reducing linear valve 162 and the maximum current Ix determined by the pressure difference of the pressure reducing linear valve 162 are obtained, and are shown in FIG. In this way, a straight line passing through a plurality of actual measurement points (in this embodiment, two actual measurement points Y1 and Y2 are acquired) is obtained. This straight line is the relationship between the differential pressure of the pressure-reducing linear valve 162 and the maximum value of the current supplied when the poppet valve portion 186 is not throttled, and is referred to as throttle characteristic in this embodiment.
Then, based on the throttle characteristics shown in FIG. 13, the maximum current (0-intercept current) when the differential pressure of the pressure reducing linear valve 162 is 0 is acquired as the learning current Ix0.

  Since the pressure-increasing linear valve 160 is a normally closed valve, if no current is supplied to the coil 180 of the pressure-increasing linear valve 160, the pressure-increasing linear valve 160 is in a closed state and the hydraulic pressure of the high-pressure source 100 should not be supplied to the control pressure chamber 122. is there. Therefore, when the temperature correction coefficient KT is acquired, the differential pressure acting force Fp acting on the pressure reducing linear valve 162 should be almost zero. On the other hand, when hydraulic fluid is supplied from the high pressure source 100 to the control pressure chamber 122 due to the situation of the pressure increasing linear valve 160, the differential pressure acting force Fp acting on the pressure reducing linear valve 162 may be greater than zero. is there. However, in this embodiment, the learning current is the maximum current Ix0 when the differential pressure of the pressure reducing linear valve 162 is 0. Therefore, the difference acting on the pressure reducing linear valve 162 when acquiring the temperature correction coefficient KT is obtained. Even if the pressure acting force Fp is larger than 0, the opening degree of the pressure-reducing linear valve 162 can be kept at the maximum opening degree.

  As shown in FIG. 10A, when the hysteresis is taken into consideration, the maximum current Ix becomes larger when the supply current to the coil 194 of the pressure reducing linear valve 162 is increased than when the supply current is decreased. Therefore, when the learning current Ix0 is determined, if the supply current to the coil 194 of the pressure reducing linear valve 162 is gradually increased, the learning current can be determined to a larger value. Even when the temperature correction coefficient KT is acquired, if the supply current to the coil 194 is increased, a current that is as large as possible can be supplied in a state in which the opening of the pressure-reducing linear valve 162 can be maintained at the maximum opening. be able to.

[5] Determination of Learning Duty Ratio In this embodiment, the voltage applied to the coil 194 is controlled by the duty control of the switching element 282 to control the current. Therefore, the duty ratio corresponding to the learning current Ix0 is determined and is set to the learning duty ratio Dx0.
The learning duty ratio Dx0 is determined based on the learning current Ix0 and the low-temperature characteristic indicated by the one-dot chain line in FIG. The low-temperature characteristic is a characteristic when the temperature is lower than the set temperature and lower than the standard temperature, and is acquired in advance and stored in the circuit characteristic storage unit 220. Further, since the learning duty ratio Dx0 is determined based on the low temperature characteristic, even when the temperature of the coil 194 is high, when the temperature correction coefficient KT is acquired, the opening degree of the pressure reducing linear valve 162 is smaller than the maximum opening degree. Therefore, an increase in the servo pressure Psrv can be suppressed satisfactorily.

The learning duty ratio is determined by executing the learning duty ratio determination program represented by the flowchart of FIG. This program is executed in a vehicle factory or the like. In this case, the hydraulic pressure including the rear hydraulic pressure control device 28 and the brake ECU 20 may be executed even when the hydraulic brake system is mounted on the vehicle. The brake system may be executed in a state where a part of the brake system is separated from the vehicle body. Further, the execution of this program is started by a predetermined start trigger (may be supplied from an external device provided in a vehicle factory or the like).
In S <b> 11, the pump motor 106 is started and the hydraulic pressure is stored in the accumulator 108. The pump motor 106 may be stopped or continuously driven after the hydraulic pressure of the accumulator 108 becomes equal to or higher than the set pressure.
In S12 to 17, the maximum current Ix1 when the servo pressure Psrv is P1 is acquired, and the actual measurement point Y1 (P1, Ix1) is acquired and stored.
In S12, the set current Ia1 is supplied to the coil 180 of the pressure increasing linear valve 160. In S13, the servo pressure Psrv (P1) is detected and stored by the servo pressure sensor 156 (Psrv1 ← P1). In S14, energization of the coil 194 of the pressure-reducing linear valve 162 is started (Ir), and the supply current Islr is set (Islr ← Ir). Thereafter, in S15, the servo pressure Psrv is detected, and it is determined whether or not the servo pressure Psrv has increased from P1 by a set value Δp or more.
If the servo pressure Psrv is substantially constant and is P1, the determination is NO, and in S16, the current flowing through the coil 194 of the pressure-reducing linear valve 162 is increased by the set current Δi, and in S14, the current applied to the coil 194 is increased. The supply current Islr is set to (Ir + Δi). In this embodiment, {(Ir + Δi), Δi, Ir} is not a control command value but a current that actually flows through the coil 194. For example, the current monitor 202 actually detects the current flowing through the coil 194 and controls the switching element 252 so that the amount of increase in current becomes Δi.
The servo pressure Psrv is gradually increased while the supply current to the coil 194 of the pressure-reducing linear valve 162 is gradually increased in a state in which S14 to 16 are repeatedly executed and the supply current (Ia1) to the coil 180 of the pressure-increasing linear valve 160 is maintained. Is detected, and it is determined whether or not it has increased by Δp or more from P1 (Psrv1). When the servo pressure Psrv becomes equal to or higher than (Psrv1 + Δp), the supply current Islr to the coil 194 of the pressure reducing linear valve 162 at that time is stored as the maximum current Ix1 in S17. The maximum current Ix1 is stored in association with the servo pressure P1, and the actual measurement point Y1 (P1, Ix1) is acquired.
In the case shown in FIG. 12, since the servo pressure Psrv has increased by Δp or more from P1 at time t1, the determination in S15 is YES, and the supply current Islr to the coil 194 at that time is set to the maximum current Ix1.

In S18 to 23, the maximum current Ix2 when the servo pressure is P2 (P2> P1) is acquired, and the actual measurement point Y2 (P2, Ix2) different from the actual measurement point Y1 is acquired.
In S18, the supply current to the coil 180 of the pressure increasing linear valve 160 is set to Ia2 (Ia2> Ia1), and in S19, the servo pressure Psrv (P2) is detected and stored (Psrv2 ← P2). Thereafter, in S20, energization of the coil 194 of the pressure-reducing linear valve 162 is started (Ir). In S21, the servo pressure Psrv is detected, and it is determined whether or not it has increased by Δp or more from P2. If the servo pressure Psrv is substantially constant (P2), the determination in S21 is NO, and the supply current to the coil 194 of the pressure-reducing linear valve 162 is increased by Δi in S22.
Thereafter, S20 to 22 are repeatedly executed, and when the detected servo pressure Psrv is equal to or higher than (P2 + Δp), the determination in S21 is YES, and in S23, supply to the coil 194 of the pressure-reducing linear valve 162 at that time point The current Islr is acquired and set to the maximum current Ix2. It is stored in association with the servo pressure P2, and the actual measurement point Y2 (P2, Ix2) is acquired.
In the case shown in FIG. 12, since the servo pressure Psrv is higher than P2 by Δp or more at time t2, the determination in S21 is YES, and the actual measurement point Y2 (P2, Ix2) is acquired in S23.

As described above, after two different measurement points Y1 (P1, Ix1) and Y2 (P2, Ix2) are acquired, in S24, as shown in FIG. 13, a straight line passing through the two measurement points Y1, Y2 is obtained. A certain aperture characteristic is acquired, and a learning current Ix0 as an intercept current is acquired. In S25, the learning duty ratio Dx0 is determined based on the low temperature characteristic indicated by the one-dot chain line in FIG. 6A and the learning current Ix0. In S26, the learning duty ratio in the storage unit 212 of the brake ECU 20 is determined. It is stored in the storage unit 224.
The aperture characteristic (learning duty ratio) can also be acquired based on three or more actually measured points Yn that are different from each other. For example, it is possible to statistically process three or more actual measurement points Yn to obtain one straight line.
In S15 and S21, when the change gradient of the servo pressure Psrv detected by the servo pressure sensor 156 is larger than the set gradient, it can be detected that the flow rate of the pressure reducing linear valve 162 has decreased. .

"Temperature correction coefficient learning"
In a vehicle having a hydraulic brake system in which the learning duty ratio Dx0 is stored, the temperature correction coefficient KT at the actual temperature is acquired by executing the temperature correction coefficient learning program represented by the flowchart of FIG. In this embodiment, it is acquired at a predetermined learning interval and in a non-operating state of the hydraulic brakes 4 and 10.
The temperature correction coefficient learning program is executed every time the temperature correction coefficient KT is acquired.
In S31, the learning interval time (timer value) is reset, and in S32, it is determined whether or not the elapsed time from the execution of S31 has reached a predetermined learning interval T0. Before reaching the learning interval T0, the elapsed time (learning interval time) is continuously measured in S33. If the elapsed time from the execution of S31 reaches the learning interval T0 by repeatedly executing S32 and 33, it is determined as the learning timing, and the determination in S32 is YES.
In S34, it is determined whether or not the hydraulic brakes 4 and 10 are in an inoperative state. In this embodiment, the determination is made by at least one of the detection value of the stroke sensor 200 and the detection value of the operation hydraulic pressure sensor 92. When the hydraulic brakes 4 and 10 are in the operating state, the determination in S34 is NO, and it is waited for the non-operating state. If the hydraulic brakes 4 and 10 are in an inoperative state, the determination is YES, and in S35, the switching element 252 is controlled with the learning duty ratio Dx0 stored in the learning duty ratio storage unit 224. In S 36, the current monitor 202 detects the current I (Ixr) flowing through the coil 194 of the pressure reducing linear valve 162. In S37, the temperature correction coefficient KT is acquired {KT = (Dx0−β) / (Ixr · αn)}, and is updated in S38. In the present embodiment, the temperature correction coefficient KT stored in the circuit characteristic storage unit 220 of the storage unit 212 is updated.

As shown in FIG. 14, every time the learning interval elapses (periodically), the temperature correction coefficient KT is learned in the non-operating state of the hydraulic brakes 4, 10. 10 needs to be operated, the current supplied to the coil 194 of the pressure-reducing linear valve 162 is controlled using the temperature correction coefficient (latest temperature correction coefficient) KT learned immediately before.
In the present embodiment, when the temperature correction coefficient KT is acquired, the maximum current in a state where the poppet valve unit 186 is not throttled is used, so that the liquid of the high-pressure source 100 is caused by leakage of the pressure-increasing linear valve 160. Even if the pressure is supplied to the control pressure chamber 122, it is satisfactorily avoided that the increase amount of the servo pressure Psrv exceeds the allowable pressure increase threshold value ΔPsth. As a result, when the temperature correction coefficient KT is acquired, the hydraulic brakes 4 and 10 are operated, and it can be well avoided that the driver feels uncomfortable.
Further, since the learning current Ix0 is used when the temperature correction coefficient KT is acquired, the actual characteristics can be acquired with high accuracy. When the hydraulic brakes 4 and 10 are requested to operate, the supply current to the coil 194 of the pressure-reducing linear valve 162 is controlled using actual characteristics, but it is possible to supply a current of an appropriate magnitude. Become. Even when the first control command value is output, it is possible to satisfactorily avoid that the supply current to the coil 194 is insufficient or excessive, and the pressure reducing linear valve 162 is used. It is possible to satisfactorily avoid the hydraulic fluid from flowing out into the reservoir 52 and generating abnormal noise, and the servo pressure Psrv can be controlled with high accuracy.

In the present embodiment, the current control unit is configured by the part that stores the linear valve control program represented by the flowchart of FIG. 7 of the brake ECU 20 and the part that executes the program, and the learning duty ratio represented by the flowchart of FIG. The actual characteristic acquisition unit includes the determination program, the part that stores the temperature correction coefficient learning program represented by the flowchart of FIG. The current control unit is a servo pressure control unit, and the actual characteristic acquisition unit is a pre-switching acquisition unit, a maximum flow rate holding unit, and a maximum opening holding unit.
In addition, the learning voltage determination unit and the learning voltage determination device are configured by a part for storing the learning duty ratio determination program represented by the flowchart of FIG. The learning voltage application time acquisition unit is configured by the part for storing the temperature correction coefficient learning program represented by the flowchart of FIG.
Further, among the actual characteristic acquisition unit, a part for storing S15-17 and S21-23 of the learning duty ratio determination program represented by the flowchart of FIG. An increase current acquisition unit is configured, a multiple pair acquisition unit is configured by a portion that stores S17 and 23, a portion that executes, etc., and an intercept current acquisition unit is configured by a portion that stores S24, a portion that executes, and the like. The low temperature characteristic correspondence determining unit is configured by the part that stores the image, the part that executes, and the like, and the diaphragm characteristic acquisition device is configured by the part that acquires the aperture characteristic in S24.
Further, it can be considered that the control pressure chamber 122 corresponds to the control target device, or that the regulator 102 corresponds to the control target device. Since the hydraulic pressure in the control pressure chamber 122 and the hydraulic pressure in the servo chamber 124 have the same magnitude, detection of the servo pressure Psrv corresponds to detection of the control pressure Psi. The control pressure Psi is a pressure on the high pressure side of the pressure reducing linear valve 162.
In the present embodiment, the learning current Ix0 and the learning duty ratio Dx0 are determined using the maximum current Ix0 at each differential pressure, and the actual characteristics are acquired by directly using the learning duty ratio Dx0. It can also be considered that the actual characteristics are acquired using the maximum current Ix0 at each differential pressure.

In the above embodiment, the learning duty ratio Dx0 is determined based on the maximum value (maximum current) Ix of the current supplied in a state where the poppet valve portion 186 is not throttled. It can also be determined based on a current smaller than the current Ix or can be determined based on a current larger than the maximum current Ix. For example, although the poppet valve unit 186 becomes a throttle, it can be determined based on a current with a small throttle effect (determined based on a current at which the difference between the maximum opening and the actual opening becomes a set value).
Further, the learning duty ratio Dx0 can also be acquired after the vehicle is shipped (the vehicle can travel). For example, it can be acquired while the ignition switch is OFF, while the shift position is the parking position, or the like. In this case, the temperature of the coil 194 may not be acquired. However, since the learning duty ratio is determined based on the acquired learning current Ix0 and the low temperature characteristics, the poppet valve unit 186 does not become a throttle. The temperature correction coefficient KT can be learned at.
Further, when the temperature correction coefficient is learned, the servo pressure Prsv is detected by the servo pressure sensor 156, and when it is larger than the set value, it can be detected that the pressure increasing linear valve 160 is leaking. . The leak determination threshold value as the set value can be determined based on the solid line in FIG.

The learning duty ratio determination program can also be stored in an external device as shown in FIG. In this embodiment, the external device 300 is mainly a computer including an execution unit 302, a storage unit 304, and the like, and a learning duty ratio determination program storage unit 306 is provided in the storage unit 304. On the other hand, in the brake ECU 310 of the vehicle, the learning duty ratio determination program storage unit is not provided in the storage unit 212. In a vehicle factory or the like, the external device 300 and the brake ECU 310 are connected, and communication of necessary information is performed between the external device 300 and the brake ECU 310, and the pressure increasing linear valve 160, the coil 180 of the pressure reducing linear valve 162, A current is supplied to 194 according to a command from the external device 300. In the external device 300, the learning duty ratio Dx0 is determined. The learning duty ratio Dx0 is supplied to the brake ECU 310 of the vehicle and stored in the learning duty ratio storage unit 224.
In this embodiment, the external device 300 and the like constitute a learning voltage determination device and an electromagnetic valve throttle characteristic acquisition device.
In addition to the above-described embodiments, the present invention can be carried out in various modifications and improvements based on the knowledge of those skilled in the art.

  20: Brake ECU 102: Regulator 122: Control pressure chamber 124: Servo chamber 156: Servo pressure sensor 160: Pressure increasing linear valve 162: Pressure reducing linear valve 180, 194: Coil 202: Current monitor 214: Control circuit 212: Storage unit 220 : Circuit characteristic storage unit 222: learning duty ratio determination program storage unit 224: learning duty ratio storage unit 252: switching element 254: resistor 300: external device 306: learning duty ratio determination program storage unit

Claims (10)

An actual characteristic acquisition unit that acquires an actual characteristic that is an actual relationship between a voltage applied to a coil of a normally open solenoid valve and a flowing current;
A pressure including a current control unit that controls the current by controlling the voltage applied to the coil of the solenoid valve based on the actual characteristic acquired by the actual characteristic acquisition unit, thereby controlling the pressure of the device to be controlled; A control device,
The actual characteristic acquisition unit includes a pre-switching acquisition unit that acquires the actual characteristic in a state after the movement of the movable member is started in the open state until the actual characteristic acquisition unit is switched to the closed state. A pressure control device.   When the differential pressure between the high pressure side and the low pressure side of the solenoid valve is constant, the pre-switching acquisition unit sets the flow rate of the fluid flowing through the solenoid valve from the maximum flow rate determined by the differential pressure of the solenoid valve. The pressure control device according to claim 1, further comprising: a maximum flow rate holding time acquisition unit that acquires the actual characteristics in a state in which the actual characteristic is not reduced.   The acquisition unit when the maximum flow rate is maintained acquires the actual characteristic by using a maximum value of a current supplied when the flow rate of the fluid flowing through the solenoid valve is the maximum flow rate. Pressure control device.   The acquisition unit before switching includes a maximum opening holding time acquisition unit that acquires the actual characteristics in a state in which the opening of the solenoid valve is not smaller than a set opening by a maximum opening of the solenoid valve. 4. The pressure control device according to any one of items 3 to 3. The solenoid valve includes a fixed throttle portion and a variable throttle portion,
The acquisition unit at the time of holding the maximum opening uses the maximum value of the current supplied to the coil when the opening area of the variable throttle unit is equal to or larger than the flow passage cross-sectional area of the fixed throttle unit, and the actual characteristics The pressure control device according to claim 4, wherein   The current flowing through the coil when the actual characteristic acquisition unit is in a predetermined state before the solenoid valve is switched from the open state to the closed state, and the coil when the temperature of the coil is lower than a set temperature. A learning voltage determining unit that determines a learning voltage that is a voltage to be applied to the coil when acquiring the actual characteristic based on a low-temperature characteristic that is a relationship between a voltage applied to and a flowing current. Or the pressure control device according to any one of 5 to 5; The electromagnetic valve is a pressure reducing control valve provided between the device to be controlled and a low pressure source;
The pressure control device includes a pressure increase control valve provided between the device to be controlled and a high pressure source,
The actual characteristic acquisition unit increases the supply current to the coil of the pressure-reducing control valve in a state where the differential pressure between the device to be controlled and the high-pressure source is kept constant by the control of the pressure-increasing control valve. While the pressure increase current acquisition unit for acquiring the supply current at the time when the pressure of the device to be controlled increases, the actual characteristics using the supply current acquired by the pressure increase current acquisition unit The pressure control device according to any one of claims 1 to 6, wherein The pressure control device is
a regulator comprising: (a) a control piston; (b) a control pressure chamber provided behind the control piston; and (c) a servo chamber provided in front of the control piston;
A pressure increase control valve provided between the control pressure chamber and the high pressure source,
The electromagnetic valve is a pressure reducing control valve provided between the control pressure chamber and a low pressure source;
The current control unit includes a servo pressure control unit that controls a pressure of the servo chamber by controlling a supply current to each of the coil of the pressure increase control valve and the coil of the pressure reduction control valve;
The actual characteristic acquisition unit
A servo pressure sensor for detecting the pressure in the servo chamber;
The pressure reduction control when the detected value of the servo pressure sensor increases while increasing the supply current to the coil of the pressure reducing control valve while the current supplied to the coil of the pressure increasing control valve is kept constant A detection value increase current acquisition unit for acquiring a supply current to the coil of the valve;
The pressure according to any one of claims 1 to 7, further comprising: a temperature correction coefficient acquisition unit that acquires a temperature correction coefficient as the actual characteristic using the current acquired by the current acquisition unit when the detected value increases. Control device. A learning voltage determination device that determines a learning voltage that is a voltage used when acquiring an actual characteristic that is an actual relationship between a voltage applied to a coil of a solenoid valve and a flowing current,
The supply current to the coil when the pressure on at least one of the high pressure side and the low pressure side of the solenoid valve changes while increasing the supply current to the coil of the solenoid valve, and the high pressure side and the low pressure side A plurality of sets acquisition unit for acquiring a plurality of sets of differential pressures with
An intercept current that obtains a supply current to the coil when the differential pressure is 0 based on a relationship between the differential pressures obtained by the multiple-set obtaining unit and the supply pressure determined by the supply currents An acquisition unit;
Low temperature characteristics for determining the applied voltage for learning based on the supply current acquired by the intercept current acquisition unit and the low temperature characteristics that are the relationship between the voltage and current when the temperature of the coil is lower than a set temperature A learning voltage determining device including a correspondence determining unit.   In a solenoid valve that includes a fixed throttle portion and a variable throttle portion, the opening area of the variable throttle portion is reduced by supplying current to the coil, and is switched from an open state to a closed state. A throttle characteristic that obtains a throttle characteristic that is a relationship between a pressure difference between the variable throttle part and a current required to make an opening area of the variable throttle part smaller than a cross-sectional area of the flow path of the fixed throttle part. Acquisition device.

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