JP2012112459A - Fluid pressure source system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure source system of high practicality.SOLUTION: The fluid pressure source system includes: a fluid pressure source device 34 having (a) a pump 30 which discharges working fluid and (b) an accumulator 32 of which the inside is divided into a working fluid chamber and a gas chamber by a partition member and accumulates the working fluid discharged from the pump in the working chamber; and an electric control unit 60 for controlling an operation of the pump. The electric control unit 60 starts the operation of the pump when an accumulator pressure falls below the lower limit threshold, stops the operation of the pump when the accumulator pressure exceeds the upper limit threshold, and further changes at least one of the lower limit threshold and the upper limit threshold on the basis of a temperature of the accumulator. According to the fluid pressure source system, the volumetric change of the working fluid chamber and the gas chamber and a change in deformation of the partition member are relatively small.

Description

  The present invention relates to a hydraulic pressure source system including a hydraulic pressure source device provided with an accumulator.

  For example, in the field of vehicles, as a hydraulic pressure source in a hydraulic brake system, a suspension stem having a hydraulic suspension cylinder, etc., a hydraulic pressure source device as described in the following patent document, that is, a pump and a discharge from the pump. A hydraulic pressure source device including an accumulator that stores hydraulic fluid to be used is used. In such a hydraulic pressure source device, generally, the accumulator pressure is controlled to be within a predetermined range.

Japanese Patent Application No. 2002-98101 Japanese Patent Application No. 2008-180279

  In the above-described hydraulic pressure source device, the accumulator pressure is set to a predetermined value by starting the pump operation when the accumulator pressure falls below the lower threshold pressure and stopping the pump operation when the accumulator pressure exceeds the upper threshold pressure. Can be kept within range. The accumulator has a partition member inside, and the hydraulic fluid chamber and the gas chamber are partitioned inside the accumulator by the partition member. Gas is sealed in the gas chamber, and the volume of the hydraulic fluid chamber and the gas chamber fluctuates with a change in the deformation amount of the partition member due to a change in accumulator pressure.

  Since the above-mentioned accumulator is required to secure a certain amount of stored hydraulic fluid, it is necessary to increase the physique to some extent when it is assumed that the volume change of the hydraulic fluid chamber increases. Further, when the volume change of the hydraulic fluid chamber and the gas chamber is increased, there is a problem that the change in the deformation amount of the partition member is increased, which is disadvantageous for the durability of the partition member. There is a lot of room for improvement in the hydraulic pressure source system including the hydraulic pressure source device including the accumulator as well as the improvement to cope with the problem. Therefore, if any improvement is made, the practicality of such a hydraulic pressure source system can be improved. This invention is made | formed in view of the said situation, and makes it a subject to provide a hydraulic pressure source system with high practicality.

  In order to solve the above problems, a hydraulic pressure source system of the present invention is a hydraulic pressure source system configured to include a hydraulic pressure source device including the accumulator and a pump, and controls to control the hydraulic pressure source device. The apparatus is characterized in that at least one of a lower threshold pressure and an upper threshold pressure that define a range in which the accumulator pressure is to be maintained is changed based on the temperature.

  Gas is sealed in the gas chamber of the accumulator, and the volume of the hydraulic fluid chamber and the gas chamber depends not only on the accumulator pressure but also on the temperature. This hydraulic pressure limit system compares the changes in volume of the hydraulic fluid chamber and gas chamber and changes in the amount of deformation of the partition member by changing one of the lower threshold pressure and the upper threshold pressure in consideration of the temperature. Can be made smaller. Therefore, the hydraulic pressure source system of the present invention is a system in which the accumulator has a relatively small physique and the partition member of the accumulator has excellent durability.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In each of the following terms, (1) corresponds to claim 1, (2) corresponds to claim 2, (4) corresponds to claim 3, (6) corresponds to claim 4, The (8) term corresponds to claim 5 and the (9) term corresponds to claim 6.

(1) (a) a pump that discharges hydraulic fluid, and (b) an accumulator that is partitioned into a hydraulic fluid chamber and a gas chamber by a partition member, and that stores the hydraulic fluid discharged from the pump in the hydraulic fluid chamber; A hydraulic pressure source device comprising:
A hydraulic pressure source system including a control device for controlling the operation of the pump,
The control device is
An accumulator that maintains the accumulator pressure within a predetermined range by starting the operation of the pump when the accumulator pressure falls below the lower threshold pressure, and stopping the operation of the pump when the accumulator pressure exceeds the upper threshold pressure. A pressure maintenance control unit;
A hydraulic pressure source system comprising: a threshold pressure changing unit that changes at least one of the lower limit threshold pressure and the upper limit threshold pressure based on a temperature of the accumulator.

  Since the gas is enclosed in the gas chamber of the accumulator and the gas follows Boyle-Charles' law, the volume of the gas chamber and the hydraulic fluid chamber depends not only on the accumulator pressure but also on the accumulator temperature. For example, when the accumulator is placed in an environment with a large temperature change, the volumes of the gas chamber and the hydraulic fluid chamber vary considerably even if the accumulator pressure is maintained within a certain range. Therefore, in consideration of the temperature of the accumulator, by changing at least one of the lower threshold pressure and the upper threshold pressure defining the range in which the accumulator pressure should be maintained, the change in the volume of the hydraulic fluid chamber, the partition member It is possible to limit the range in which deformation is allowed to be relatively small. Therefore, in the hydraulic pressure source system of this section, it is not necessary to provide a large margin with respect to the required amount of stored hydraulic fluid, and the physique of the accumulator itself can be reduced for the required amount of storage. Moreover, the burden on the partition member can be made relatively small, and the durability of the accumulator, specifically, the durability of the partition member is improved.

  If the influence of the elastic reaction force of the partition member is small and there is not much difference between the pressure in the hydraulic fluid chamber and the pressure in the gas chamber, the pressure of the hydraulic fluid in the hydraulic fluid chamber is adopted as the “accumulator pressure” in this section. Alternatively, the pressure of the gas in the gas chamber may be adopted. Furthermore, you may employ | adopt the pressure of the hydraulic fluid supplied from the hydraulic fluid chamber in the location connected with a hydraulic fluid chamber. Similarly, the “accumulator temperature (hereinafter sometimes simply referred to as“ accumulator temperature ”)” has no significant difference in the temperature in the gas chamber, the temperature in the hydraulic fluid chamber, and the environmental temperature in which the accumulator is located. If considered, any one of the environmental temperatures may be adopted. In many accumulators, the sum of the volume of the gas chamber and the volume of the hydraulic fluid chamber can be considered to be constant, and when the volume of one of the gas chamber and the hydraulic fluid chamber increases, the volume of the other chamber Decrease by minutes.

  The “control device” may be configured mainly by a computer. In this case, functional units such as the “accumulator pressure maintenance control unit” and the “threshold pressure change unit” are realized by executing a specific program. Become. The specific change mode of at least one of the lower limit threshold pressure and the upper limit threshold pressure by the “threshold pressure changing unit” will be described in detail in some of the items listed below.

  (2) The accumulator has a metal bellows as the partition member in the interior thereof, and the interior is partitioned into the hydraulic fluid chamber and the gas chamber by the metal bellows (1 ) Hydraulic pressure source system.

  As the “compartment member”, a rubber diaphragm or the like can be adopted. However, in the system of this section, the partition member is limited to a metal bellows. As the metal bellows, for example, a metal bellows having a bellows-like tube portion and a plate-like end surface portion that closes the end surface of the tube portion can be used. Such a metal bellows has a bellows-like cylindrical portion formed relatively thin, and the cylindrical portion repeatedly expands and contracts as the volume of the gas chamber and the hydraulic fluid chamber changes. . From such a viewpoint, it is particularly effective to change at least one of the lower threshold pressure and the upper threshold pressure based on the accumulator temperature for a system that employs an accumulator having a metal bellows. In the accumulator in this aspect, the inside of the metal bellows may be a working fluid chamber and the outside may be a gas chamber. Conversely, the outside of the metal bellows may be a working fluid chamber, May be a gas chamber.

  (3) When the temperature of the accumulator is a reference temperature, the lower limit threshold pressure and the upper limit threshold pressure are set to the reference lower limit threshold pressure and the reference upper limit threshold pressure, respectively (1) or ( The hydraulic pressure source system according to item 2).

  This section shows the preconditions for some of the following sections. The “reference temperature” in this section is, for example, a normal temperature such as 20 ° C. or 25 ° C., in other words, a normal temperature in an environment where the accumulator is placed, an average temperature, a median temperature in a temperature fluctuation range, or those The temperature may be in the vicinity of. It is not necessary to set the reference temperature. In other words, any temperature higher than the set low temperature and any temperature lower than the set high temperature described later may be used.

(4) The threshold pressure changing unit is
When the temperature of the accumulator is lower than a set low temperature set below the reference temperature, the upper threshold pressure is changed so as to be lower than the reference upper limit threshold pressure. Source system.

  The lower the accumulator pressure, and the higher the accumulator temperature, the larger the volume of the gas chamber and the smaller the volume of the hydraulic fluid chamber. Conversely, the higher the accumulator pressure, the higher the accumulator temperature. The lower the volume, the smaller the volume of the gas chamber and the larger the volume of the hydraulic fluid chamber. Therefore, the volume of the gas chamber and the volume of the hydraulic fluid chamber are each when the accumulator pressure is the upper limit threshold pressure at the lowest estimated accumulator temperature (hereinafter, sometimes referred to as “lowest temperature upper limit pressure”). And the volume when the accumulator pressure is the lower limit threshold pressure at the highest actually assumed accumulator temperature (hereinafter, sometimes referred to as “at the maximum temperature lower limit pressure”). That is, the volume at the lowest temperature upper limit pressure (hereinafter sometimes referred to as “the lowest temperature upper limit pressure volume”) and the maximum temperature lower limit pressure (hereinafter sometimes referred to as “the highest temperature lower limit pressure volume”) Is the maximum amount of change in volume of each of the gas chamber and the hydraulic fluid chamber (hereinafter sometimes referred to as “maximum volume change amount”). As the volume of the gas chamber and the hydraulic fluid chamber changes, the deformation amount of the partition member of the accumulator changes between the deformation amount at the lowest temperature upper limit pressure and the deformation amount at the highest temperature lower limit pressure. That is, the difference between the deformation amount at the lowest temperature upper limit pressure and the deformation amount at the highest temperature source pressure is the maximum amount of change in the deformation amount of the partition member (hereinafter, sometimes referred to as “maximum deformation change amount”). Become.

  In consideration of the above, in the hydraulic pressure source system of this section, when the accumulator temperature is lower than the “set low temperature” (hereinafter sometimes simply referred to as “low temperature”), the upper threshold pressure is lowered. Therefore, the volume at the lowest temperature upper limit pressure is shifted toward the volume at the highest temperature lower limit pressure. That is, the volume at the lowest temperature upper limit pressure of the gas chamber is increased, in other words, the volume at the lowest temperature upper limit pressure of the hydraulic fluid chamber is decreased. As a result, in this system, the maximum volume change amount of each of the gas chamber and the hydraulic fluid chamber is suppressed, and the maximum deformation change amount of the partition member is suppressed from increasing.

  The “set low temperature” in this section may be set to a temperature lower than the reference temperature, or may be set to a temperature equal to the reference temperature. Note that the mode in this section does not prohibit changing the lower threshold pressure, and prohibiting the upper threshold pressure to be higher than the reference upper threshold pressure when the accumulator temperature is higher than the set low temperature. Not what you want.

(5) When the volume of one of the hydraulic fluid chamber and the gas chamber when the accumulator pressure is the upper threshold pressure under the set low temperature is defined as an upper limit pressure limit volume,
When the temperature of the accumulator is lower than the set low temperature, the threshold pressure changing unit sets the upper threshold pressure to the hydraulic fluid chamber and the gas chamber at the upper threshold pressure regardless of the temperature of the accumulator. The hydraulic pressure source system according to the item (4), wherein one volume of the is changed so as to be the limit volume at the time of the upper limit pressure.

  In the aspect of this section, the volume of each of the gas chamber and the hydraulic fluid chamber when the accumulator pressure is the upper limit threshold pressure (hereinafter sometimes referred to as “the upper limit pressure volume”) is generally constant at low temperatures. It becomes. When the set low temperature is set as the reference temperature, the volume at the upper limit pressure is substantially the same as the volume at the upper limit pressure under the reference temperature at a low temperature.

(6) The threshold pressure changing unit is
When the temperature of the accumulator is higher than a set high temperature set to be equal to or higher than the reference temperature, the lower threshold pressure is changed to be higher than the reference lower limit threshold pressure (3) to (5) The hydraulic pressure source system according to any one of the above.

  In the hydraulic pressure source system of this section, when the accumulator temperature is higher than the “set high temperature” (hereinafter sometimes simply referred to as “high temperature”), the lower limit pressure is increased to increase the maximum temperature at the lower limit pressure. The volume is shifted toward the volume at the lowest temperature upper limit pressure. That is, the volume at the maximum temperature / lower limit pressure of the gas chamber is reduced, in other words, the volume at the maximum temperature / lower limit pressure of the hydraulic fluid chamber is increased. As a result, in this system, the maximum volume change amount of each of the gas chamber and the hydraulic fluid chamber is suppressed, and the maximum deformation change amount of the partition member is suppressed from increasing.

  The “set high temperature” in this section may be set to a temperature higher than the reference temperature, or may be set to a temperature equal to the reference temperature. Note that the mode of this section does not prohibit changing the upper threshold pressure, and when the accumulator temperature is lower than the set high temperature, prohibiting the lower threshold pressure from being lower than the reference lower threshold pressure. Not what you want.

(7) When the volume of one of the hydraulic fluid chamber and the gas chamber when the accumulator pressure is the lower limit pressure under the set high temperature is defined as a lower limit pressure limit volume,
When the temperature of the accumulator is higher than the set high temperature, the threshold pressure changing unit sets the lower threshold pressure to the hydraulic fluid chamber and the gas chamber at the lower threshold pressure regardless of the temperature of the accumulator. The fluid pressure source system according to the item (6), wherein one volume of the fluid is changed so as to be the limit volume at the time of the lower limit pressure.

  In the aspect of this section, the volume of each of the gas chamber and the hydraulic fluid chamber when the accumulator pressure is the lower limit threshold pressure (hereinafter sometimes referred to as “volume at the lower limit pressure”) is generally constant at high temperatures. Become. When the set high temperature is set as the reference temperature, the lower limit pressure volume at the high temperature is substantially the same as the lower limit pressure volume under the reference temperature.

(8) The threshold pressure changing unit is
The difference between the one volume of the hydraulic fluid chamber and the gas chamber when the accumulator pressure becomes the lower limit threshold pressure and the one volume when the accumulator pressure becomes the upper limit threshold pressure is the temperature of the accumulator. The hydraulic pressure source system according to any one of (1) to (7), wherein at least one of the lower limit threshold pressure and the upper limit threshold pressure is changed so as to be constant regardless.

  In the aspect of this section, the above “difference” (hereinafter sometimes referred to as “upper and lower limit volume difference”), which is the difference between the upper limit pressure volume and the lower limit pressure volume of each of the gas chamber and the hydraulic fluid chamber, is an accumulator. It is almost constant regardless of temperature. According to the aspect of this section, the supply amount of the hydraulic fluid can be stabilized, and the difference between the deformation amount of the partition member at the upper limit threshold pressure and the deformation amount of the partition member at the lower limit threshold pressure (hereinafter referred to as “upper and lower limits”). Since there is a case where the difference in deformation amount is sometimes constant, the system is considerably superior in terms of durability of the partition member. In this embodiment, at least one of the lower limit threshold pressure and the upper limit threshold pressure may be changed so that the upper and lower limit volume difference is constant only at a low temperature or a high temperature. In both cases, at least one of the lower limit threshold pressure and the upper limit threshold pressure may be changed so that the upper and lower limit volume differences are constant. Further, at least one of the lower limit threshold pressure and the upper limit threshold pressure may be changed so that the upper and lower limit volume differences are constant over the entire temperature fluctuation range assumed.

  In order to realize the aspect of this section at a low temperature, for example, the upper limit threshold pressure may be determined according to the aspect of (5), and the lower limit threshold pressure may be determined so that the upper and lower volume difference is constant. In order to realize the aspect of this item at a high temperature, the lower limit pressure is determined according to the aspect of (7), and the upper limit pressure is determined so that the upper and lower volume difference is constant. . Furthermore, when realizing the aspect of this section over the entire temperature fluctuation range, the upper and lower limit volume differences at the low temperature and the high temperature are the upper and lower volume differences at the reference temperature (hereinafter referred to as “reference upper and lower volume differences”). The lower limit threshold pressure and the upper limit threshold pressure are determined as described above, and in the temperature range between the set low temperature and the set high temperature, the upper and lower limit volume difference is also in that temperature range. What is necessary is just to determine the other, making one of an upper limit threshold pressure and a lower limit threshold pressure constant so that it may become a reference | standard upper / lower limit volume difference. If the set low temperature and the set high temperature are made to coincide with the reference temperature and the aspect of this section is realized at the low temperature and the high temperature, each of the gas chamber and the hydraulic fluid chamber over the entire fluctuation range of the accumulator temperature. Both the lower limit pressure volume and the upper limit pressure volume are substantially constant, and the maximum volume change amount of each of the gas chamber and the hydraulic fluid chamber and the maximum deformation change amount of the partition member are approximately the same as those at the reference temperature. become.

(9) The control device
An accumulator temperature estimating unit that estimates the temperature of the accumulator based on a pressure increase rate of the accumulator pressure when the pump is operating, and the accumulator estimated by the accumulator temperature estimating unit is a threshold pressure changing unit The hydraulic pressure source system according to any one of (1) to (8), wherein at least one of the lower limit threshold pressure and the upper limit threshold pressure is changed based on the temperature of (1).

  When considering the capacity of the pump to be constant, if considered simply, when the pump is operated, the hydraulic fluid is supplied to the hydraulic fluid chamber of the accumulator at a constant speed, and the volume of the hydraulic fluid chamber at a constant speed. Will increase. With the increase, the volume of the gas chamber decreases at a constant speed. The pressure increase speed of the accumulator pressure accompanying this volume reduction depends on the accumulator temperature, and it can be considered that the pressure increase speed increases as the temperature increases. Utilizing this fact, the system of this section estimates the accumulator temperature based on the increasing speed of the accumulator pressure. In the system of this section, it is not necessary to separately provide a sensor for detecting the accumulator temperature, and the system can be simplified.

  The accumulator temperature may be estimated, for example, based on the pressure increase rate when the pressure is increased from a specific accumulator pressure. More specifically, for example, the difference between the accumulator pressure and the lower threshold pressure when the pump is operated for a set time from the lower threshold pressure at which the pump is started, and the accumulator pressure is lower than the lower threshold pressure. What is necessary is just to estimate by an appropriate index value for indexing the pressure increase speed, such as the operation time of the pump until a set pressure higher than the pressure. For estimation, for example, the index value is measured in advance at various accumulator temperatures, and the measured index value is stored as a reference index value in the form of map data. The current accumulator temperature may be estimated by comparing with the index value. Note that the accumulator pressure increase speed depends on other factors such as fluctuations in the power supply voltage for operating the pump, and therefore it is desirable to take these factors into account.

1 is a hydraulic circuit diagram showing a vehicle hydraulic brake system that includes a hydraulic pressure source system that is an embodiment of the claimable invention; FIG. It is sectional drawing of the accumulator with which the hydraulic-pressure source apparatus shown in FIG. It is a graph which shows the relationship between the volume of the gas chamber of the accumulator of FIG. 2, and a pressure in various temperatures. It is a schematic diagram which shows the mode of expansion / contraction of the bellows when the accumulator of FIG. 2 becomes the lowest temperature upper limit pressure volume and the highest temperature lower limit pressure volume. It is a graph which shows the relationship between the volume of a gas chamber, and a pressure in various accumulator temperature. It is a graph which shows the change of the upper limit threshold pressure and the lower limit threshold pressure with respect to accumulator temperature, and the graph which shows the change of the volume at the time of the upper limit pressure of a gas chamber, and the volume at the time of a lower limit pressure. A graph showing the relationship between the pump operating time required to increase the accumulator pressure from the lower threshold pressure to the upper threshold pressure and the accumulator temperature, and a graph showing the change in the coefficient for correcting the accumulator temperature relative to the change in the lower threshold pressure 4 is a graph showing a change in a coefficient for correcting the accumulator temperature with respect to a change in power supply voltage for operating the pump. It is a flowchart which shows the hydraulic pressure source control apparatus program performed with a control apparatus in order to control a hydraulic pressure source apparatus. It is a flowchart which shows the temperature estimation subroutine performed in a hydraulic-pressure-source apparatus control program in order to estimate an accumulator temperature based on the time when the pump is operating. It is a flowchart which shows the upper and lower limit threshold pressure determination subroutine performed in a hydraulic-pressure-source apparatus control program in order to determine a lower limit threshold pressure and an upper limit threshold pressure based on an accumulator temperature. It is a flowchart which shows the pump operation control subroutine performed in a hydraulic-pressure-source apparatus control program in order to maintain an accumulator pressure in a predetermined range.

  Hereinafter, as a form for carrying out the claimable invention, a hydraulic pressure source system which is an embodiment of the claimable invention will be described in detail with reference to the drawings. In addition to the following examples, the claimable invention is implemented in various forms including various modifications and improvements based on the knowledge of those skilled in the art, including the form described in the above [Aspect of the Invention] section. can do.

≪Configuration of hydraulic brake system≫
The hydraulic pressure source system of the embodiment constitutes a part of the vehicle hydraulic brake system shown in FIG. This brake system is provided with four wheels 10 corresponding to four wheels 10 (FL, FR, RL, and RR in the figure are the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively). A brake device 12 is provided. Each brake device 12 is a general disc brake device including a wheel cylinder, a caliper, a brake pad, a disc, and the like. The system includes a master cylinder 18 that pressurizes hydraulic fluid (hydraulic oil) stored in a reservoir 14 that is a low pressure source by an operating force applied by a driver to an operating member (brake pedal) 16, and the master cylinders 18 and 4. A control valve device 20 interposed between the two brake devices 10 and a stroke simulator 24 connected to the master cylinder 18 via an electromagnetic on-off valve 22 are provided. The system further includes a hydraulic pressure source device 34 including a pump 30 for pressurizing the hydraulic fluid stored in the reservoir 14 and an accumulator 32 for storing the hydraulic fluid pressurized thereby at a high pressure. The hydraulic fluid from the hydraulic pressure source device 34 is supplied to the four brake devices 12 via the control valve device 20.

  The control valve device 20 is a general one mainly composed of four pairs of electromagnetic linear valves corresponding to the four brake devices 10, and each pair of electromagnetic linear valves includes a pressure increasing linear valve 40 and a pressure reducing linear valve. The valve 42 is configured. In addition, the control valve device 20 is a pair of master cut valves 44 each of which is an electromagnetic on-off valve for prohibiting the supply of hydraulic fluid from the master cylinder 18 and the pressure of hydraulic fluid from the hydraulic pressure source device 34. To detect the pressure of the hydraulic fluid supplied to the corresponding brake device 12 (hereinafter sometimes referred to as “brake pressure”). 4, the master pressure sensor 50 for detecting the pressure of the hydraulic fluid supplied from the master cylinder 18 (hereinafter sometimes referred to as “master pressure”), and the hydraulic fluid from the hydraulic pressure source device 34. An accumulator pressure sensor 52 for detecting the pressure of the accumulator 32 (hereinafter sometimes referred to as “accumulator pressure”).

  The control of this system, more specifically, the control of each electromagnetic valve and pump 30 is an electronic control unit (ECU) that includes a drive circuit for driving each electromagnetic valve and pump 30 while mainly using a computer. 60. In order to execute the control, the ECU 60 is connected to each of the sensors 48, 50, 52, and an operation force sensor 62 provided on the operation member 16 for detecting the operation force.

  In the event of an electrical failure, the hydraulic fluid from the master cylinder 18 is allowed to be supplied to the two brake devices 12 of the front wheels, and a braking force that depends on the operating force is generated. The hydraulic fluid from the hydraulic pressure source device 34 is prohibited from being supplied, and the hydraulic fluid from the hydraulic pressure source device 34 is supplied to the four brake devices 12 to generate a braking force depending on the hydraulic fluid pressure of the hydraulic pressure source device 34. It is done. More specifically, normally, the supply current to the pressure-increasing linear valve 40 and the pressure-decreasing linear valve 42 is controlled based on the operating force detected by the operating force sensor 62, so that the pressure corresponding to the operating force is controlled. The hydraulic fluid is supplied to each brake device 12.

  The hydraulic pressure source device 34 is a general plunger pump that is operated by an electromagnetic motor that is a driving source of the hydraulic pressure source device 34. The hydraulic pressure source device 34, that is, the pump 30 is controlled by an accumulator pressure sensor 52. The accumulator pressure detected is executed so as to be within a predetermined range. Specifically, an upper limit threshold pressure and a lower limit threshold pressure that respectively define an upper limit and a lower limit of a predetermined range are determined, and when the accumulator pressure falls below the lower limit threshold pressure, the operation of the pump 30 is started and exceeds the upper limit threshold pressure. If this happens, the operation of the pump 30 is stopped. In the ECU 60, the part that executes this control can be considered as a functional unit named a hydraulic pressure source device control unit 64, and the functional unit functions as a control unit for controlling the hydraulic pressure source device 34. . Therefore, the hydraulic pressure source system of the embodiment is configured by the functional units in the hydraulic pressure source device 34, the accumulator pressure sensor 50, and the ECU 60.

≪Accumulator structure and volume change of gas chamber and hydraulic fluid chamber≫
The accumulator 32 included in the hydraulic pressure source device 34 has a structure as shown in cross section in FIG. The accumulator 32 is roughly composed of a housing 70 serving as a housing, and a metal bellows 72 having a bellows-like periphery inside the housing 70. The housing 72 includes a cylindrical housing main body 74, a port forming member 76 fitted into one end surface of the housing main body 74, and a lid 78 that closes the other end of the housing main body 74. The lid 78 is provided with a hole penetrating itself, and the hole is closed by a plug 79.

  The port forming member 76 is provided with a hole 80 that penetrates itself in the axial direction and functions as a port. The port forming member 76 is joined to the housing main body 74 in a state where one end of the port forming member 76 is fitted into a hole provided in one end surface of the housing main body 74. A buffer rubber 82 is fitted on the end face of the one end. On the other hand, the other end of the port forming member 76 protrudes outward and is connected to the pump 30, and the hydraulic fluid pressurized by the pump 30 flows into the housing 70.

  The bellows 72 in the housing 70 is configured to include a bellows member 84 serving as a cylindrical portion, and a disk 86 joined to the bellows member 84 as an end surface portion that closes one end of the bellows member 84. The other end of the bellows member 84 is joined to the lid 78 so as to close the other end. Therefore, the inside of the bellows 72 is in a sealed state. The bellows member 84 is made of a relatively thin metal and can expand and contract. The elongation of the bellows 72 is regulated by the disc 86 coming into contact with the buffer rubber 82. In the accumulator 32 having such a structure, the inside thereof is divided into an external chamber formed outside the bellows 72 and an internal chamber formed inside the bellows 72 by a bellows 72 which is a partition member. Yes. The external chamber is a hydraulic fluid chamber R1 filled with high-pressure hydraulic fluid supplied from the pump 30. On the other hand, a predetermined amount of gas, specifically nitrogen gas, is injected into the internal chamber from a hole provided in the lid 78 and is sealed by a plug 79. Therefore, the internal chamber is a gas chamber R2 filled with a specified amount of gas.

  In the accumulator 32 configured as described above, when the hydraulic fluid flows into the hydraulic fluid chamber R1 by the operation of the pump 30, the volume of the hydraulic fluid chamber R1 increases, the bellows 72 contracts, and the volume of the gas chamber R2 decreases. On the other hand, when the hydraulic fluid in the hydraulic fluid chamber R1 flows out, the bellows 72 extends and the volume of the gas chamber R2 increases. As described above, in the accumulator 32, the deformation due to the expansion and contraction of the bellows 72 causes the hydraulic fluid chamber R1 and the gas chamber R2 to change so that one volume change amount is almost equal to the other volume change amount. Therefore, it can be considered that the sum of the volume of the hydraulic fluid chamber R1 and the volume of the gas chamber R2 is almost constant. Further, since the elastic reaction force generated by the deformation of the bellows member 84 of the bellows 72 is considerably small, it is considered that the pressure of the working fluid in the working fluid chamber R1 and the pressure of the gas in the gas chamber R2 are hardly affected. be able to. Therefore, in the accumulator 32, it can be considered that the hydraulic pressure that is the pressure of the hydraulic fluid is almost equal to the gas pressure that is the pressure of the gas. In other words, the bellows 72 expands and contracts so that the hydraulic fluid pressure and the gas pressure are equal. Therefore, in the accumulator 32, either the hydraulic fluid pressure or the gas pressure can be considered as the accumulator pressure.

  Accordingly, the accumulator pressure becomes a magnitude corresponding to the volumes of the hydraulic fluid chamber R1 and the gas chamber R2. That is, the relationship between the above-described upper limit threshold pressure and lower limit threshold pressure and the volume of the hydraulic fluid chamber R1 and the volume of the gas chamber R2 will be described. The hydraulic fluid chamber R1 and gas when the accumulator pressure is the upper limit threshold pressure. The volume at the upper limit pressure, which is the volume of each chamber R2, is relatively large in the hydraulic fluid chamber R1, and relatively small in the gas chamber R2. That is, a relatively large amount of hydraulic fluid is stored in the accumulator 32. On the other hand, the lower limit pressure volume, which is the volume of each of the hydraulic fluid chamber R1 and the gas chamber R2 when the accumulator pressure is the lower threshold pressure, is relatively small in the hydraulic fluid chamber R1, and relatively small in the gas chamber R2. growing. That is, the accumulator 32 can store only a relatively small amount of hydraulic fluid.

  While the accumulator pressure and the amount of hydraulic fluid in the hydraulic fluid chamber R1 are in the above relationship, the relationship between the accumulator pressure and the volume of the gas chamber R2 follows the Boyle-Charles law. In accordance with the change in the temperature of the accumulator 32, it changes as shown in FIG. In other words, the relationship between the gas pressure P, volume V, and temperature T is PV / T = R in one mole of gas, where R is the gas constant. Therefore, when the operation of the pump 30 is controlled depending on only the upper limit threshold pressure and the lower limit threshold pressure, the volume of the hydraulic fluid chamber R1 and the volume of the gas chamber R2 at the respective threshold pressures change according to the temperature, respectively. It becomes. In addition, the range in which the temperature of the accumulator 32 changes should be widely assumed to be −30 ° C. to 90 ° C. in consideration of various environments in which the vehicle is used. Therefore, when the accumulator temperature is −30 ° C. and 90 ° C., the volume of the hydraulic fluid chamber R1 and the volume of the gas chamber R2 vary considerably as shown in FIG. Specifically, the volume of the hydraulic fluid chamber R1 and the volume of the gas chamber R2 at the accumulator temperature of −30 ° C. change as shown in FIG. 4A at the upper threshold pressure and the lower threshold pressure, respectively. To do. On the other hand, the volume of the hydraulic fluid chamber R1 and the volume of the gas chamber R2 at the accumulator temperature of 90 ° C. change as shown in FIG. 4B at the upper threshold pressure and the lower threshold pressure, respectively. Therefore, at the lowest temperature upper limit pressure, that is, at the upper threshold pressure at −30 ° C., the hydraulic fluid chamber R1 is the largest and the gas chamber R2 is the smallest. Further, at the maximum temperature lower limit pressure, that is, at the lower limit threshold pressure at 90 ° C., the hydraulic fluid chamber R1 is the smallest and the gas chamber R2 is the largest. That is, the difference between the volume at the lowest temperature upper limit pressure, that is, the volume at the lowest temperature upper limit pressure, and the volume at the highest temperature lower limit pressure, that is, the volume at the highest temperature lower limit pressure, is the difference between the hydraulic fluid chamber R1 and the gas chamber R2. It becomes the maximum volume change amount in each volume change. As the volume of the hydraulic fluid chamber R1 and the gas chamber R2 changes, the deformation amount of the bellows 72 changes between the deformation amount at the lowest temperature upper limit pressure and the deformation amount at the highest temperature lower limit pressure. That is, the difference between the deformation amount at the lowest temperature upper limit pressure and the deformation amount at the highest temperature source pressure becomes the maximum deformation change amount in the change in the deformation amount of the bellows 72. When the change in the deformation amount of the bellows 72 becomes large in this way, the accumulator 32 needs a large margin with respect to the required amount of stored hydraulic fluid. In addition, an increase in the deformation amount of the bellows 72 is not preferable in terms of durability of the bellows 72.

≪Determination of upper and lower threshold pressures≫
In this system, an upper limit threshold pressure P _U and a lower limit threshold pressure P _L are determined according to the accumulator temperature T, and the hydraulic pressure source device control unit 64 is based on the upper limit threshold pressure P _U and the lower limit threshold pressure P _L. Controls the operation of the pump 30. In the accumulator 32, 20 ° C. is the reference temperature T ₂₀ of the accumulator temperature T, the upper limit threshold pressure P _{U at the} reference temperature is the reference upper limit threshold pressure P _20U , and the lower limit threshold pressure P _L is the reference lower limit threshold pressure P _20L . It has become. Therefore, when the accumulator temperature T is 20 ° C. (hereinafter sometimes referred to as “reference temperature”), the operation of the pump 30 is started when the accumulator pressure P becomes the reference lower limit threshold pressure P _20L or less. When the accumulator pressure P reaches the reference upper limit threshold pressure P _20U or more, the operation of the pump 30 is stopped. That is, the upper limit threshold pressure P _U and the lower limit threshold pressure P _L at the reference temperature are respectively determined by the following equations.
P _U = P _20U
P _L = P _20L

When the accumulator temperature T is in the range of lower than 20 ° C. and higher than 0 ° C. (hereinafter sometimes referred to as “at very low temperature”), the upper limit threshold pressure P _U is the same as the reference upper limit threshold pressure P _20U. Is done. Further, at the time of fine low temperature, the upper and lower limit volume difference [Delta] V, that is, the difference between the upper limit pressure time volume and lower pressure time volume of each of the hydraulic fluid chamber R1 and the gas chamber R2, the reference upper limit threshold pressure P gas chamber at _{20 U} R2 The reference upper / lower limit volume difference ΔV ₂₀ that is the difference between the upper limit pressure reference volume V _20U that is the volume of the gas and the upper limit pressure reference volume V _20L that is the volume of the gas chamber R2 at the reference lower limit threshold pressure P _20L is substantially constant. To be kept. Therefore, the lower limit threshold pressure P _L is determined so that the upper and lower limit volume difference is kept constant at the reference upper and lower limit volume difference ΔV ₂₀ . Therefore, the volume obtained by adding the reference upper and lower limit volume difference ΔV ₂₀ to the upper limit pressure volume V _U that is the volume at the upper limit threshold pressure becomes the lower limit pressure volume V _L that is the volume at the lower limit threshold pressure, and the lower limit threshold pressure P _L is calculated as the pressure in the lower limit pressure volume _VL . That is, the upper limit threshold pressure P _U and the lower limit threshold pressure P _{L at a} very low temperature are respectively determined by the following equations.
P _U = P _20U
P _L = R · T / (V _U + ΔV ₂₀ )
= T / {(T / P _U ) + (T ₂₀ / P _20L -T ₂₀ / P _20U )}
The accumulator temperature T and the reference temperature T ₂₀ used in the equation are values converted into absolute temperatures. The same applies to the following equations.

When the accumulator temperature T is in the range lower than 0 ° C. and higher than −30 ° C. (hereinafter sometimes referred to as “low temperature”), the volume of the gas chamber R2 is the upper limit pressure limit volume V _0U , that is, When the accumulator temperature T is 0 ° C. and the upper limit threshold pressure P _U is the reference upper limit threshold pressure P _20U , the upper limit pressure volume V _U is kept substantially constant. Therefore, the upper limit threshold pressure P _U at a low temperature can be calculated as the pressure in the upper pressure time limit volume V _0U. In addition, the lower limit threshold pressure P _L is determined so that the upper / lower limit volume difference ΔV is kept substantially constant at the reference upper / lower limit volume difference ΔV ₂₀ even at low temperatures. Therefore, the upper limit pressure time limit volume V _0U reference minimum volume difference [Delta] V ₂₀ the volume lower limit pressure time volume V _L becomes plus, the lower limit threshold pressure P _L is possible to calculate the pressure at the lower pressure time volume V _L Can do. That is, the upper limit threshold pressure P _U and the lower limit threshold pressure P _L at low temperatures are respectively determined by the following equations.
P _U = R · T / V _0U = T / (T ₀ / P _20U )
P _L = R · T / (V _0U + ΔV ₂₀ )
_{= T / {(T 0 /} P 20U) + (T 20 / P 20L -T 20 / P 20U)}

When the accumulator temperature T is in the range of higher than 20 ° C. and lower than 50 ° C. (hereinafter sometimes referred to as “slightly high temperature”), the lower limit threshold pressure P _L is the same as the reference lower limit threshold pressure P _20L. Sato In addition, at the very high temperature, the upper limit threshold pressure P _U is determined so that the upper and lower limit volume difference ΔV is kept substantially constant at the reference upper and lower limit volume difference ΔV ₂₀ . Therefore, the volume obtained by subtracting the reference upper / lower limit volume difference ΔV ₂₀ from the lower limit pressure volume V _L becomes the upper limit pressure volume V _U , and the upper limit threshold pressure P _U is calculated as the pressure in the upper limit pressure volume V _U. That is, the upper limit threshold pressure P _U and the lower limit threshold pressure P _L at a slightly high temperature are determined by the following equations, respectively.
P _U = R · T / (V _L −ΔV ₂₀ )
= T / {(T / P L) - (T 20 / P 20L -T 20 / P 20U)}
P _L = P _20L

When the accumulator temperature T is in the range of higher than 50 ° C. and lower than 90 ° C. (hereinafter sometimes referred to as “high temperature”), the volume of the gas chamber R2 is the lower limit pressure limit volume V _50L , that is, the accumulator. When the temperature T is 50 ° C. and the lower limit threshold pressure P _L is the reference lower limit threshold pressure P _20L , the lower limit pressure volume V _L is kept substantially constant. Therefore, the lower limit threshold pressure P _L at this high temperature can be calculated as the pressure in the lower limit pressure limit volume V _50L . Further, the upper limit threshold pressure P _U is determined so that the upper and lower limit volume difference ΔV is kept substantially constant at the reference upper and lower limit volume difference ΔV ₂₀ even at high temperatures. Therefore, the volume obtained by subtracting the reference upper and lower limit volume difference ΔV ₂₀ from the lower limit pressure limit volume V _50L becomes the upper limit pressure volume V _U , and the upper limit threshold pressure P _U is calculated as the pressure at the upper limit pressure volume V _U. Can do. That is, the upper limit threshold pressure P _U and the lower limit threshold pressure P _L at a high temperature are respectively determined by the following equations.
P _U = R · T / (V _50L −ΔV ₂₀ )
_{= T / {(T 50 /} P 20L) - (T 20 / P 20L -T 20 / P 20U)}
P _L = R · T / V _50L = T / (T ₅₀ / P _20L )

FIG. 5 is a graph showing the relationship between the volume V of the gas chamber R2 and the pressure P according to the accumulator temperature T, and depicts the change in the upper limit threshold pressure P _{U and} the change in the lower limit threshold pressure P _L. It is a graph. FIG. 6A is a graph showing changes in the upper limit threshold pressure P _U and the lower limit threshold pressure P _L with respect to the accumulator temperature T, and FIG. is a graph showing changes in V _U and the lower limit pressure time volume V _L. Further, in FIG. 6B, when the upper limit threshold pressure P _U and the lower limit threshold pressure P _L are not changed, that is, the upper limit threshold pressure P _U is made constant at the reference upper limit threshold pressure P _20U . changes in gas chamber volume V when the lower limit threshold pressure P _L is constant at the reference lower limit threshold pressure P _20L are shown respectively by the chain line. As shown in these figures, the upper limit threshold pressure P _U is lowered when the accumulator temperature T is in the range of −30 to less than 0 ° C. Therefore, the lowest temperature upper limit pressure volume is shifted toward the highest temperature lower limit pressure volume. That is, 0 ° C. is a set low temperature in this system. Further, the lower limit threshold pressure P _L is increased when the accumulator temperature T is in the range of higher than 50 and 90 ° C. or lower. Therefore, the maximum temperature lower limit pressure volume is shifted toward the lowest temperature upper limit pressure volume. That is, 50 ° C. is a set high temperature in the present system.

By changing the upper limit threshold pressure P _U and the lower limit threshold pressure P _L described above, the upper / lower limit volume difference ΔV becomes substantially constant at the reference upper / lower limit volume difference ΔV ₂₀ regardless of the accumulator temperature T. Therefore, in this system, the supply amount of hydraulic fluid can be stabilized. In this system, the difference between the upper and lower limit deformation amounts, that is, the difference between the deformation amount of the bellows 72 at the upper limit threshold pressure P _U and the deformation amount of the bellows 72 at the lower limit threshold pressure P _L is substantially constant. The durability of can be improved. Furthermore, in this system, the upper limit threshold pressure P _U and the lower limit threshold are set so that the bellows 72 does not deform beyond the deformation amount at the upper limit pressure limit volume V _0U and the lower limit pressure limit volume V _50L . The pressure P _L is changed. As a result, in this system, the maximum volume change amount of each of the hydraulic fluid chamber R1 and the gas chamber R2 is suppressed, and the maximum deformation change amount of the bellows 72 is suppressed. Therefore, the physique of the accumulator 32 is small for the amount of storage required for the accumulator 32.

≪Estimation of actuator temperature≫
In the hydraulic pressure source device control unit 64 of the ECU 60, when the accumulator pressure P falls below the lower limit threshold pressure P _L determined as described above, the operation of the pump 30 is started, and when the accumulator pressure P exceeds the upper limit threshold pressure P _U , the pump Control is executed so that the operation of 30 is stopped. At this time, assuming that the capacity of the pump 30 to discharge the hydraulic fluid is almost constant, the time required for the hydraulic fluid of the reference upper and lower limit volume difference ΔV ₂₀ to be stored in the accumulator 32, that is, the pump The time t during which 30 is operating decreases as the accumulator temperature T increases. That is, as the accumulator temperature T is higher, the pump 30 can increase the accumulator pressure P from the lower limit threshold pressure P _L to the upper limit threshold pressure P _{U in} a shorter time. In this system, the accumulator temperature T is estimated by measuring the operating time t of the pump 30 as an index value. Therefore, the ECU 60 stores map data of the accumulator temperature T in which the reference index value is the pump operation time t as shown in FIG. Therefore, this system does not require a separate sensor for detecting the accumulator temperature, and the accumulator temperature can be estimated on the basis of the pressure increase speed of the accumulator pressure, so that the system is simple.

However, in the present system, as described above, the lower limit threshold pressure P _L and the upper limit threshold pressure P _U are changed. Accordingly, the ECU 60 stores map data of the lower limit threshold pressure-dependent correction coefficient k _P for correcting the estimated accumulator temperature T in accordance with the lower limit threshold pressure P _U as shown in FIG. 7B. Has been. In addition, the pump 30 operates with power supplied from a battery mounted on the vehicle. The magnitude of the voltage of the electric power changes according to the amount of electricity stored in the battery, and the ability of the pump 30 to discharge the hydraulic fluid changes depending on the magnitude of the voltage. For this reason, the ECU 60 stores map data of a voltage-dependent correction coefficient k _E for correcting the estimated accumulator temperature T according to the battery voltage E as shown in FIG. Therefore, the accumulator temperature T estimated from the pump operation time t is corrected by the following equation using the map data shown in FIG.
T = k _P・ k _E・ T

≪Control program and ECU functional part≫
The hydraulic pressure source device control unit 64 of the ECU 60 executes a hydraulic pressure source device control program that is a program for controlling the hydraulic pressure source device 34. This program is repeatedly executed in a relatively short cycle (for example, several milliseconds to several tens of milliseconds). FIG. 8 shows a flowchart of the hydraulic pressure source device control program. In the process according to this flowchart, a temperature estimation subroutine for estimating the accumulator temperature is executed in step 1 (hereinafter abbreviated as “S1”, the same applies to other steps), and in S2, the upper limit threshold pressure P _U , lower threshold pressure determination subroutine above for determining the lower limit threshold pressure P _L is performed, in S3, the pump operation control subroutine for controlling the operation of the pump 30 is executed.

FIG. 9 shows a flowchart of the temperature estimation subroutine. In the process according to this flowchart, it is determined in S11 whether or not the brake is being operated. If the brake is being operated, the temperature estimation is cancelled. On the other hand, if the brake operation is not performed, it is determined in S12 whether the pump 30 is stopped or operating. If it is determined that the pump 30 is operating, the time t during which the pump 30 is operating is measured in S13. The pump operating time t is measured by integrating the time interval Δt to be executed each time this subroutine is executed. When the measurement of the pump operation time t is started, the flag F ₂ is set to 1 in S14. In S12, when the pump 30 is determined to stopped, in S15, whether the flag F ₂ is set to 1 it is determined. When the flag F ₂ is set to 1, the measurement of the pump operation time t is completed from the Δt accumulated so far, the accumulator temperature T is estimated in S16, and the map data described above in S17 to S19. , The lower threshold pressure-dependent correction coefficient k _P and the voltage-based correction coefficient k _E are determined, respectively. In S20, the accumulator temperature T is corrected by these correction coefficients, and the pump operation time t and the flag F ₂ are initialized, that is, set to 0.

FIG. 10 shows a flowchart of a subroutine for executing the upper / lower threshold pressure determining subroutine. In the process according to this flowchart, it is determined in S31 whether or not the accumulator temperature T is 20 ° C., that is, the reference temperature. If it is 20 ° C., the upper limit threshold pressure P _U is the reference upper limit threshold pressure P _20U , the lower limit. The threshold pressure P _L is set to the reference lower limit threshold pressure P _20L . In S33, it is determined whether or not the accumulator temperature T is at a very low temperature, that is, whether T ₂₀ > T ≧ T _{0. If} the accumulator temperature T is at a very low temperature, in S34, the upper limit threshold pressure P _U and the lower limit are set according to the above formula. The threshold pressure P _L is calculated respectively. In S35, it is determined whether or not the accumulator temperature T is low, that is, whether T ₀ > T. If the accumulator temperature T is low, in S36, the upper threshold pressure P _U and the lower threshold pressure P _L are determined according to the above formula. Each is calculated. In S37, it is determined whether or not the accumulator temperature T is at a very high temperature, that is, whether T ₂₀ <T ≦ T _50, and if it is at a very high temperature, in S38, the upper limit threshold pressure P _U and the lower limit are The threshold pressure P _L is calculated respectively. If the accumulator temperature T does not apply to any of the above determinations, it is determined that the accumulator temperature T is high, that is, T ₅₀ <T. In S39, the upper limit threshold pressure P _U and the lower limit threshold are determined according to the above formula. Each of the pressures P _L is calculated. The accumulator temperature T is set to 20 ° C., whose initial value is the reference temperature.

FIG. 11 shows a flowchart of a pump operation control subroutine. In the process according to this flowchart, in S51, the flag F _1, the pump 30 is either stopped or whether in operation or not. The flag F ₁ is set to 0 when the pump 30 is stopped, and is set to ₁ when the pump 30 is operating. If it is determined that the pump 30 is stopped, it is determined in S52 whether the accumulator pressure P is lower than the lower limit threshold pressure P _L. If the accumulator pressure P is below the lower threshold pressure P _L , the pump 30 is activated and the flag F ₁ is set to 1. On the other hand, if it is determined in S51 that the pump 30 is operating, it is determined in S55 whether the accumulator pressure P exceeds the upper limit threshold pressure P _U. If the accumulator pressure P exceeds the upper threshold pressure P _U , the pump 30 is stopped and the flag F ₁ is set to zero.

Each time the vehicle ignition is turned ON, the hydraulic pressure source device control program is initialized. By the initialization, the accumulator temperature T is set to the reference temperature of 20 ° C., and the flags F ₁ and F ₂ and the pump operation time t are also set to 0, and the execution of the program is started. The threshold pressure at 20 ° C., that is, the reference upper limit threshold pressure P _20U , the reference lower limit threshold pressure P _20L , the upper limit pressure reference volume V _20U that is the volume of the gas chamber R2 at these threshold pressures, and the upper limit pressure reference volume As for V _20L , a value measured in advance is stored in the ECU 60.

≪Control program and ECU functional part≫
In the ECU 60, the execution of the hydraulic pressure source device control program can be considered to be performed by the hydraulic pressure source device control unit 64, and the hydraulic pressure source device control unit 64 executes several subroutines for executing the above-described subroutines. It can be considered to have a functional part. Specifically, as shown in FIG. 1, the hydraulic pressure source device control unit 64 includes a temperature estimation unit 90 that executes a temperature estimation subroutine, an upper and lower threshold pressure determination unit 92 that executes an upper and lower threshold pressure determination subroutine, It can be considered to have a pump operation control unit 94 that executes a pump operation control subroutine. That is, the temperature estimation unit 90 includes an accumulator temperature estimation unit that estimates the accumulator temperature T based on the pressure increase rate of the accumulator pressure when the pump 30 is operating, and the upper and lower threshold pressure determination unit 92 includes the lower limit threshold pressure P. A threshold pressure changing unit that changes at least one of _L and the upper limit threshold pressure P _U based on the accumulator temperature T; a pump operation control unit 94; an accumulator pressure maintaining control unit that maintains the accumulator pressure within a predetermined range; Can think.

  The hydraulic pressure source system of the claimable invention can be used in a wide range of fields such as the above-described vehicle hydraulic brake system and the vehicle suspension system having a suspension cylinder that is operated by hydraulic pressure.

  30: Pump 32: Accumulator 34: Hydraulic pressure source device 60: Electronic control unit (control device) 72: Bellows (partition member) 90: Temperature estimation unit (accumulator temperature estimation unit) 92: Upper / lower limit threshold pressure determination unit (threshold pressure) 94: Pump operation control unit (accumulator pressure maintenance control unit) R1: Working fluid chamber R2: Gas chamber

Claims (6)

(a) a pump that discharges hydraulic fluid; and (b) an accumulator that is partitioned into a hydraulic fluid chamber and a gas chamber by a partition member, and that stores the hydraulic fluid discharged from the pump in the hydraulic fluid chamber. A hydraulic source device;
A hydraulic pressure source system including a control device for controlling the operation of the pump,
The control device is
An accumulator that maintains the accumulator pressure within a predetermined range by starting the operation of the pump when the accumulator pressure falls below the lower threshold pressure, and stopping the operation of the pump when the accumulator pressure exceeds the upper threshold pressure. A pressure maintenance control unit;
A hydraulic pressure source system comprising: a threshold pressure changing unit that changes at least one of the lower limit threshold pressure and the upper limit threshold pressure based on a temperature of the accumulator.   The said accumulator has the metal bellows as the said division member in the inside, The inside is divided by the said metal bellows into the said hydraulic fluid chamber and the said gas chamber, It is comprised. Hydraulic source system. The threshold pressure changing unit is
The upper limit threshold pressure is changed to be lower than the reference upper limit threshold pressure when the temperature of the accumulator is lower than a set low temperature set to be equal to or lower than the reference temperature. Hydraulic source system. The threshold pressure changing unit is
The hydraulic pressure source according to claim 3, wherein when the temperature of the accumulator is higher than a set high temperature set to be equal to or higher than the reference temperature, the lower limit threshold pressure is changed to be higher than the reference lower limit threshold pressure. system. The threshold pressure changing unit is
The difference between the one volume of the hydraulic fluid chamber and the gas chamber when the accumulator pressure becomes the lower limit threshold pressure and the one volume when the accumulator pressure becomes the upper limit threshold pressure is the temperature of the accumulator. The hydraulic pressure source system according to any one of claims 1 to 4, wherein at least one of the lower limit threshold pressure and the upper limit threshold pressure is changed so as to be constant regardless of the difference. The control device is
An accumulator temperature estimating unit that estimates the temperature of the accumulator based on a pressure increase rate of the accumulator pressure when the pump is operating, and the accumulator estimated by the accumulator temperature estimating unit is a threshold pressure changing unit The hydraulic pressure source system according to any one of claims 1 to 5, wherein at least one of the lower limit threshold pressure and the upper limit threshold pressure is changed on the basis of the temperature.

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