JPH044257Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a spool-type electromagnetic pressure control valve, and in particular includes a reaction rod for applying a fluid reaction force of a magnitude corresponding to the control pressure to the spool. This invention relates to an improvement in the pressure control valve provided.

2. Description of the Related Art Electromagnetic pressure control valves are already known which control the pressure of a fluid to a level corresponding to the magnitude of the excitation current by controlling the excitation current of a solenoid. This type of electromagnetic pressure control valve generally controls the pressure of the fluid continuously sent from the pump, so internal leakage, that is, leakage from the gap between the valve element and the housing within the control valve, can occur. There is no problem even if there is. However, there are also applications where this internal leakage must be prevented as much as possible. For example, in a hydraulic brake system for an automobile, the hydraulic pressure of a wheel cylinder is controlled by brake fluid stored in an accumulator. In order to control the wheel cylinder hydraulic pressure using the brake fluid stored in the accumulator, the electromagnetic pressure control valve must be normally closed, and if there is an internal leak in this electromagnetic pressure control valve, The brake fluid stored in the accumulator is wasted due to this internal leakage. Since the operating time of automotive hydraulic brake systems is significantly shorter than the non-operating time, and the amount of brake fluid consumed is usually relatively small, the consumption of brake fluid due to internal leakage is a non-negligible amount. This results in a clear decrease in energy efficiency.

Since it is generally difficult to prevent internal leakage of spool type electromagnetic pressure control valves, it has conventionally been considered that they cannot be used for this type of application. However, in recent years, the precision of machining has improved significantly, and it has become possible to suppress the clearance between the housing and the spool to a few microns or less, and with this level of clearance, internal leakage becomes negligible.

Therefore, the inventors of the present invention prototyped a spool-type electromagnetic pressure control valve shown in FIG. 2 for use in controlling the hydraulic pressure of a wheel cylinder of a hydraulic brake system for an automobile. This is a high pressure port 102, a low pressure port 1
A spool 112 is slidably and substantially fluid-tightly fitted into a valve hole 110 in a housing 108 having a control pressure port 106 and a control pressure port 106 to which a magnetic control force of a solenoid 114 is applied. , a reaction rod 116 extending axially from one end surface of the spool 112.
The cross-sectional area of the reaction rod 116 and the valve hole 11 are exposed to the atmosphere.
A fluid reaction force having a magnitude multiplied by the fluid pressure within 0 is applied to the spool 112, and the spool 112 is moved based on the fluid reaction force and the control force so that the control pressure port 106 By selectively communicating with the high pressure port 102 and the low pressure port 104, the fluid pressure of the control pressure port 106 is controlled to a level corresponding to the magnitude of the excitation current of the solenoid 114.

One side clearance between the outer peripheral surface of the spool 112 and the inner peripheral surface of the valve hole 110 is made extremely small.
An O-ring 12 is connected between the outer peripheral surface of the reaction rod 116 and the inner peripheral surface of the reaction rod hole 118.
Sealed by 0.

According to this spool-type electromagnetic pressure control valve, the hydraulic pressure in the wheel cylinder can be controlled to a height that is approximately proportional to the magnitude of the excitation current of the solenoid 114, and internal leakage within the control valve can be ignored. It can be made as small as possible.

Problems that the invention aims to solve: However, there are considerable variations in wheel cylinder fluid pressure for a constant excitation current, and there is hysteresis in the fluid pressure control characteristics, making it difficult to say that fluid pressure control accuracy is sufficiently high. It was.

If the O-ring 120 is removed, the accuracy of hydraulic pressure control will be significantly improved, but the amount of liquid leaking from the clearance between the reaction rod 116 and the housing 108 will increase, reducing energy efficiency. Another problem arises in that it becomes difficult to

Means for Solving the Problem In order to solve this problem, the present invention provides a spool-type electromagnetic pressure control valve comprising the housing, spool, solenoid, reaction rod, etc., in which the reaction rod is separate from the spool body. A separate body, connected to the spool body so that it can move relative to the spool body in the radial direction, and cannot be separated from the spool body beyond a certain limit in the axial direction,
In addition, by reducing the clearance between the outer circumferential surface of the reaction rod and the inner circumferential surface of the reaction rod hole, a metal-to-metal seal is formed to prevent fluid (liquid or gas) from leaking from the valve hole.

As mentioned above, if the reaction rod is made separate from the spool body and can be moved relative to it in the radial direction, the misalignment of the axes of the spool body and the reaction rod, and the misalignment between the valve hole and the reaction rod hole can be avoided. Discrepancies in the center lines can be absorbed by relative movement in the radial direction between the spool body and the reaction rod, so not only the clearance between the outer circumferential surface of the spool body and the inner circumferential surface of the valve hole but also the reaction rod The clearance between the outer peripheral surface and the inner peripheral surface of the reaction rod hole can also be made extremely small to form a metal-to-metal seal. The frictional force of the metal-to-metal seal is about one order of magnitude smaller than that of a sealing member such as an O-ring, and leakage is negligible.

Although the reaction rod is separate from the spool, it is connected to the spool so that it cannot be separated beyond a certain limit, so the force applied to the reaction rod by the hydraulic pressure in the valve hole is transmitted to the spool. The reaction rod functions similarly to a conventional spool-mounted reaction rod.

Effects of the Invention Therefore, according to the present invention, it is possible to obtain a spool-type electromagnetic pressure control valve that has sufficiently high pressure control accuracy and little internal leakage, and can be manufactured at low cost.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a system diagram conceptually showing an electrically controlled hydraulic brake system for automobiles. A spool type electromagnetic hydraulic control valve 10, which is an embodiment of the present invention, uses an accumulator 12 as a hydraulic pressure source to control the brake. It is provided to control the hydraulic pressure of the wheel cylinder 14. The pedal force on the brake pedal 16 as a brake operating member is detected by the pedal force sensor 18,
An excitation current proportional to the pedal force on the brake pedal 16 is supplied to the solenoid 22 of the hydraulic pressure control valve 10 from a solenoid control circuit 20 connected to the pedal force sensor 18 , and the hydraulic pressure in the wheel cylinder 14 is adjusted to the pressure on the brake pedal 16 . The height is controlled in proportion to the pedal effort. Brake fluid pumped up from a reservoir 24 by a pump 26 is stored in the accumulator 12, and the hydraulic pressure in the accumulator 12 is detected by a hydraulic pressure sensor 28, and the output signal of this hydraulic pressure sensor 28 is The motor 32 is controlled by the motor control circuit 30 based on this, so that the hydraulic pressure within the accumulator 12 is maintained within a certain range.

The hydraulic control valve 10 includes a housing 40 made of non-magnetic material. A valve hole 42 is formed in the housing 40, and a spool body 45, which together with a reaction rod 43 constitutes a spool 44, is slidably fitted into the valve hole 42. The clearance between the outer circumferential surface of the spool body 45 and the inner circumferential surface of the valve hole 42 is extremely small, 10 μm or less in diameter, and a metal-to-metal seal is formed between the outer circumferential surface and the inner circumferential surface. Spool body 4
5 is made of a magnetic material, and an appropriate number of annular grooves (not shown) are formed on the outer peripheral surface so that the hydraulic pressure acts almost evenly on the entire circumference, and the spool body 45 slides easily. It is made to be. housing 40
is the high pressure port 4 connected to the accumulator 12
6, a low pressure port 48 connected to the reservoir 24 and a control pressure port 50 connected to the wheel cylinder 14. The spool body 45 includes an axial hole 52 passing through it in the axial direction, and a first radial hole 54 and a second radial hole 56 extending radially from the axial hole 52 and opening to the outer peripheral surface. ing.

A spring 62 is disposed between the spool body 45 and a yoke 60 made of a magnetic material fixed to the housing 40, and urges the spool body 45 toward the original position shown in the figure. When the spool body 45 is in its original position, the first radial hole 54
is in communication with the low pressure port 48 and the control pressure port 50, and as a result, the hydraulic pressure in the valve hole 42 and the wheel cylinder 14 is equal to the hydraulic pressure (atmospheric pressure) in the reservoir 24. However, when an excitation current is supplied to the solenoid 22 and the yoke 60 is magnetized, a magnetic attraction force acts on the spool body 45 as a control force, and the spool 44 resists the biasing force of the spring 62 to the left in FIG. move towards This breaks communication between the first radial hole 54 and the low pressure port 48, and if the spool 44 moves further to the left, the second radial hole 56 comes into communication with the high pressure port 46. During this time, the control pressure port 50 is always in communication with the valve hole 42 via the first radial hole 54. The relative positions of each port 46, 48, 50 and the first and second radial holes 54, 56 are thus determined. Note that the reason why a hole is formed in the yoke 60 to pass through it in the axial direction is to introduce brake fluid into this hole to cool the yoke 60.

At the end of the spool body 45 on the yoke 60 side,
A ring-shaped stopper 66 made of a non-magnetic material is fixed, and as this stopper 66 comes into contact with the yoke 60, the spool body 45 is prevented from being directly attracted to the yoke 60.

A reaction rod 43 is attached to the end of the spool body 45 on the opposite side from the yoke 60 side. The reaction rod 43 has a much smaller diameter than the spool body 45, and is slidably fitted into the reaction rod hole 72 formed in the housing 40 with a clearance of 5 μm or less in diameter. Although not shown, an appropriate number of annular grooves are formed on the outer peripheral surface of the reaction rod 43 at a distance in the axial direction, so that the reaction rod 43 can slide easily. There is. The reaction rod 43 has a large-diameter head 74 at the end on the spool body 45 side, and the engagement of this head 74 with an engaging portion 76 provided on the spool body 45 causes the spool body 45 to The separation limit from Further, a spring 78 is disposed between the head 74 and the spool body 45, and the reaction rod 43 is connected to the spool body 45.
It is maintained at the maximum distance from the That is, the reaction rod 43 is fixed to the spool body 45 in the axial direction, but can freely move relative to the spool body 45 in the radial direction. In addition, spring 7
8 is provided to prevent the reaction rod 43 from moving accidentally when the hydraulic control valve 10 is not activated, and is not essential. Even if the spring 78 is not provided,
When the hydraulic pressure control valve 10 is activated, the reaction rod 43 is pushed toward the low pressure chamber 80 by the hydraulic pressure in the valve hole 42, and is separated from the spool body 45 by the maximum distance, thereby performing its function. . Furthermore, the brake fluid slightly leaking from the minute clearance between the reaction rod 43 and the reaction rod hole 72 is returned from the low pressure chamber 80 to the reservoir 24.

The force balance of the spool 44 in the hydraulic pressure control state of the present hydraulic pressure control valve 10 is expressed by the following equation.

S=CI...(1) S=PA+F+R...(2) However, S: Attraction force of yoke 60 to spool body 45 C: Constant I: Excitation current to solenoid 22 P: Valve hole 42 and control pressure port 50 Hydraulic pressure A: Cross-sectional area F of reaction rod 43: Biasing force R of spring 62: Sliding resistance of reaction rod 43 and spool body 45 From equations (1) and (2), P = (C/A) I -(F+R)/A...(3) is obtained. In this hydraulic pressure control device 10, the reaction rod 43 and the housing 40
The spool 44, which consists of the reaction rod 43 and the spool body 45, is Sliding resistance is so small that it can be ignored. Therefore, P≒(C/A)IF/A...(4). That is, the hydraulic pressure P in the valve hole 42 and the control pressure port 50 is proportional to the exciting current I to the solenoid 22. Also, spool 4
Since the sliding resistance of No. 4 is small, variations in control fluid pressure and hysteresis in control characteristics are also significantly reduced.

The magnitude of the excitation current to the solenoid 22 is controlled by the solenoid control circuit 20 so as to be proportional to the depression force on the brake pedal 16 detected by the depression force sensor 18. The pressure is controlled to a height proportional to the depression force on the brake pedal 16.

Moreover, in this hydraulic pressure control valve 10, the spool 44 is connected to the spool body 45 and the reaction rod 4.
3 and allow relative movement in the radial direction between the two, it is necessary to increase the concentricity between the spool body 45 and the reaction rod 43 and the concentricity between the valve hole 42 and the reaction rod hole 72. Since the dimensional accuracy of the outer diameter of the spool body 45 and the reaction rod 43 and the inner diameter of the valve hole 42 and the reaction rod hole 72 can be made high, it is easy to make the clearance between them extremely small. Therefore, a hydraulic control valve 10 with negligible internal leakage can be manufactured at low cost.

One embodiment of the present invention has been described in detail above, but
This is literally an example, and it goes without saying that the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view schematically showing a spool type electromagnetic hydraulic control valve which is an embodiment of the present invention.
It is also a system diagram of an electrically controlled hydraulic brake system for an automobile including the hydraulic pressure control valve. Figure 2 shows
1 is a front cross-sectional view schematically showing a spool-type electromagnetic hydraulic control valve that was prototyped prior to the completion of the present invention. 10... Spool type electromagnetic hydraulic control valve, 40...
Housing, 42...Valve hole, 43...Reaction rod, 44...Spool, 45...Spool body, 46...High pressure port, 48...Low pressure port, 50...Control pressure port, 60...Yoke, 6
2...Spring, 72...Reaction rod hole.

Claims (1)

[Claims for Utility Model Registration] A spool is slidably and substantially liquid-tightly fitted into a valve hole in a housing having a high pressure port, a low pressure port, and a control pressure port, and a magnetic While a control force is applied, the distal end surface of the reaction rod extending in the axial direction from one end surface of the spool is exposed to the outside of the valve hole, thereby increasing the cross-sectional area of the reaction rod and the inside of the valve hole. A fluid reaction force having a magnitude equal to the product of the fluid pressure is applied to the valve spool, and the valve spool is moved based on the fluid reaction force and the control force, so that the control pressure port is connected to the high pressure port. A spool-type electromagnetic pressure control valve in which the fluid pressure of the control pressure port is controlled to a height corresponding to the magnitude of the excitation current of the solenoid by selectively communicating with the low pressure port, the reaction rod being selectively communicated with the low pressure port. It is separate from the spool body, is movable relative to the spool body in the radial direction, is connected to the spool body in an axial direction such that it cannot be separated from the spool body beyond a certain limit, and has an outer peripheral surface of the reaction rod. A spool-type electromagnetic pressure control characterized in that a metal-to-metal seal is formed to prevent fluid leakage from the valve hole by reducing the clearance between the valve hole and the inner circumferential surface of the reaction rod hole formed in the housing. valve.