DE102012205329A1 - Pressure control valve - Google Patents

Abstract

The invention relates to a pressure regulating valve (10) for regulating the pressure in a high pressure accumulator (12) for a fuel injection system. The pressure control valve (10) is designed in two stages. The pressure regulating valve (10) comprises a first valve stage (20) for a smaller flow within a first operating range of the pressure regulating valve (10). Furthermore, the pressure regulating valve (10) comprises a further, second valve stage (42) for a large flow within a second operating range of the pressure regulating valve (10).

Description

State of the art

DE 102 31 135 A1 refers to a pressure relief valve. The pressure relief valve comprises a closing element, which is displaceable axially in the opening direction against the force acting in the closing direction of a closing spring in a bore. The closing element rests against a valve seat when the pressure relief valve is closed and closes off an inlet. In the inlet, a piston is integrated, which is connected via a connecting element with the closing element and within the inlet in the axial direction is displaceable.

Today, pressure control valves are frequently used in fuel injection systems, for example in the common rail system. The said pressure control valves have to work in a very large working range of very small flow rates at very high pressures to very high flow rates at low pressures and ensure high dynamics. This makes it increasingly difficult to find an optimal valve design for the entire operating range with increasing nominal pressures of the high-pressure reservoirs.

Disclosure of the invention

According to the invention, a pressure regulating valve is proposed, which is used for regulating the pressure in a high-pressure accumulator, for example in a high-pressure accumulator for a fuel injection system (common rail). The pressure control valve is designed in two stages and has a first valve stage, which is designed for a smaller flow within a first operating range of the pressure control valve and also a second valve stage, which is designed for a larger flow within a second operating range of the present invention proposed pressure control valve.

Advantageously, the first valve stage is a solenoid valve and the second valve stage is a hydraulic valve. The first valve stage and the second valve stage are formed in a common valve insert which can be received on an end face of a tubular high-pressure accumulator of a fuel injection system for vehicles. The common valve insert is, for example, a solid metal body provided with an external thread.

The pressure regulating valve proposed according to the invention operates in two stages, whereby it can cover different operating ranges, which are characterized by different operating parameters, through the two valve stages realized in these. While the first valve stage, which is a solenoid valve, is optimized for a first operating range that can be characterized by very small required valve flows, the second valve stage, which is designed as a hydraulic valve, is optimized for use at high flow rates. In this way, the operating range of the present invention proposed pressure control valve is divided with respect to the flow in two zones, for which the zones respectively associated valve stage can be optimized separately and independently. With regard to increasing requirements with regard to a nominal pressure of the high-pressure accumulator and for other flow ranges, simple scalability is provided by the design of a servo mechanism in the pressure control valve proposed according to the invention. A sensible separation of the two different operating ranges is made most sensibly by a maximum adjustable throttle cross-section. For the first valve stage applies a maximum effective cross section of 0.05 mm ² , while for the second valve stage, which is designed as a hydraulic valve, a maximum adjustable throttle cross-section of up to 0.3 mm ² applies.

Due to the compact construction of the pressure regulating valve proposed according to the invention, both valve stages can be formed in one and the same externally threaded valve insert, in which a control chamber is formed, which can be filled via an inlet throttle passage extending through the common valve insert. This control chamber in the common valve insert is pressure-relieved by a first closing element, which may be spherical, for example. The closing element belonging to the first valve step, in particular a ball-shaped closing element, is actuated by a rod-shaped valve member which can be actuated via a magnet coil which comprises the first valve stage, which is advantageously designed as a solenoid valve. Said first valve stage realizes a direct control of the pressure in the pressure accumulator, in particular a high-pressure accumulation chamber of a fuel injection system for vehicles at low flow rates and a very high pressure level. The first valve stage, i. the solenoid valve of the present invention proposed pressure valve actuated at a corresponding pressure reduction in the control chamber, the second valve stage, which is designed as a hydraulic valve, and is activated in a second operating range of the inventively proposed pressure control valve, if larger flow rates must be realized at a lower pressure level in the high-pressure accumulator.

The mode of operation of the pressure regulating valve proposed according to the invention arises in this way in that the first valve stage is actuated by means of the electromechanical actuator, ie is designed as a solenoid valve, at the opening of which the pressure in the control chamber is reduced. The control chamber, which can be relieved of pressure by the first valve stage, is refilled with fuel via the aforementioned inlet throttle channel, which extends through the common valve insert. When required for pressure control in the high-pressure accumulator small flow, in the present context <50 l / h, with the first valve stage, the system pressure, ie the pressure prevailing in the high-pressure accumulator pressure can be controlled directly, as long as the pressure in the control chamber is not below an opening pressure for an actuator for the second valve stage, which is designed as a hydraulic valve, drops. In normal operation, it is desirable to set as little flow as possible so as not to unnecessarily waste energy.

In the mentioned actuator is advantageously a pressure booster, which is formed substantially piston-shaped. One end of the piston-shaped pressure booster projects into the pressure chamber which can be relieved of pressure via the first valve stage, while the opposite end of the piston-shaped pressure booster acts on a closing element of the second valve stage which, for example, is likewise spherically formed. As long as the pressure in the control chamber does not fall below an opening pressure of the piston-shaped pressure booster, the pressure level in the high-pressure reservoir is controlled directly with the first valve stage.

The transition from the small flow rates needed for pressure control to larger flow rates, i. the flow limit or a flow transition region is dependent on the design of the inlet throttle channel for the control chamber and the pressurizable surface of the piston-shaped pressure booster, which projects into the control chamber and a closing spring and the seat diameter of the piston-shaped pressure booster actuated hydraulic valve.

If a higher flow is needed to control the pressure, the second valve stage, i. the hydraulically operated valve is used in addition to the first valve stage. For this purpose, the pressure in the control chamber by opening the first valve stage must be reduced so far that the pressure booster enters the control chamber and consequently releases the second closing element from the second valve seat of the second valve stage, so that larger flows can be achieved.

As soon as the first closing element formed as a solenoid valve is placed back in its valve seat, a pressure build-up in the control chamber, so that the piston-shaped pressure booster again supported by the action of the closing spring and the second preferred spherical-shaped closing element again in the second valve seat poses. If the pressure control valve is completely closed, only a small amount of leakage will escape via a preparation-related guide gap of the piston-shaped pressure booster.

Advantages of the invention

The inventively proposed solution of a two-stage pressure control valve allows optimization of each of the two valve stages for the respective work areas. The two valve stages, one of which is designed as a solenoid valve and the other as a hydraulic valve, can be optimized for each different operating ranges separately and independently. Higher flexibility in designing the individual valve stages and the use of a servo mechanism ensures high scalability, i. the pressure control valve proposed according to the invention can also be adapted to other operating ranges by appropriate selection of parameters, for example, with increasing nominal operating system pressure.

Another salient advantage of the present invention's proposed pressure control valve is the automatic actuation of the second valve, i. of the hydraulic valve after actuation of the first valve stage, i. the solenoid valve as soon as the latter reaches a certain pressure level in the control chamber.

The proposed solution according to the invention further enables a very simple scalability for changing requirements or operating range by respectively adjusting the hydraulically effective diameter of the servo mechanism and the inlet throttles. The electromechanically actuated valve stage, i. the first valve stage remains unchanged. By the inventively proposed pressure control valve, a larger usable operating range (over volume flow) by optimizing the first valve stage to flows below 50 l / h at pressures up to> 3000 bar and the second valve stage at high flow rates up to 400 l / h and low pressures of 150 bar up to 500 bar. A proportionality of the drive current with respect to the pressure shown in each case can be used to control the pressure (control principle open loop) with known flow.

Brief description of the drawings

With reference to the drawings, the invention will be described in more detail below.

It shows:

1 a section through the inventively proposed two valve stages comprehensive pressure control valve,

2 the pressure control valve according to 1 when closed,

3 the present invention proposed pressure control valve at low flow rates and activated first valve stage and

4 the inventively proposed two-stage pressure control valve in realization of a large flow rate and activated first and second valve stage.

Embodiments of the invention

The representation according to 1 It can be seen that a pressure regulating valve proposed according to the invention 10 at a high-pressure accumulator 12 is included. In the high-pressure accumulator 12 is, for example, a high-pressure common rail, as it is used in fuel injection systems on internal combustion engines of passenger cars or trucks use. The inventively proposed pressure control valve 10 is at an end face of the tubular high-pressure accumulator 12 added. The high-pressure accumulator 12 includes a cavity 14 in which the fuel under very high pressure is stored. The pressure level in the cavity 14 the high-pressure accumulator 12 is maintained by a non-illustrated high-pressure pumping unit, in particular a high-pressure pump continuously. The pressure level in the cavity 14 the high-pressure accumulator 12 is on the order of 1,800 bar to 2,000 bar or even higher. That in the cavity 14 the high-pressure accumulator 12 prevailing pressure level is also referred to as Railsystemdruck.

As 1 further shows is in the material of the high-pressure accumulator 12 a valve core 16 admitted. The valve insert 16 has on its lateral surface, for example, a screw thread 18 on, with which the valve insert 16 in the solid material of the high-pressure accumulator 12 is screwed.

The valve insert 16 takes a first valve stage 20 on, which may be formed in an advantageous manner as a solenoid valve, further comprises a second valve stage 42 , which is designed as a hydraulic valve. The first valve stage 20 , which is a solenoid valve, includes a solenoid 22 , About this solenoid is a first valve seat by means of an actuating element 24 the first valve stage 20 opening or closing this first closing element 26 actuated. The example spherical shaped first closing element 26 closes or opens an outlet throttle 28 in the first valve seat 24 so that a control room 30 in the common valve core 16 is absorbed, pressure relieved. The control room 30 in the common valve insert 16 is about a through the solid material of the common valve core 16 extending inlet throttle channel 44 pressurized. The first valve stage is a first return channel 32 assigned, which in a common return area 34 empties.

In the pressure-relieved by the first valve stage control chamber 30 protrudes an end face of a piston-shaped pressure booster 38 into it. The piston-shaped pressure intensifier 38 Can be over a closing spring 40 be acted upon in the closing direction. The closing spring 40 For example, it can be accommodated on a region of the piston-shaped pressure booster which is tapered with regard to its diameter and is advantageously supported on the underside of the first valve seat 24 from. The piston-shaped pressure intensifier 38 acts on a second closing element 48 , which is in particular spherical and part of the second valve stage 42 is, which is designed as a hydraulic valve. As shown in the illustration 1 removable, becomes the second closing element 48 by the piston-shaped pressure booster 38 in a second valve seat 42 , the one valve funnel 70 has pressed. The second valve seat 52 comprises a tubular preform 50 and a throttle bore 56 through which the cavity 14 the high-pressure accumulator 12 with the inlet throttle channel 44 for filling the control room 30 connected is. How out 1 further, the second valve seat is shown 52 over biting edges 54 on the plan side of the solid material of the high pressure accumulator 12 centered.

In the common valve insert 16 is a valve room 66 formed, from which a second return channel 46 to the common return 34 on the low pressure side of the pressure control valve 10 runs. Along the pressure intensifier 38 that is between the control room 30 and the second closing element 48 extends, passes a production-related guide gap 64 over which a leakage current 58 flows out (see illustration according to 2 ).

A contact zone between the piston-shaped pressure booster 38 on the one hand and the circumference of, for example, spherically shaped second closing element 48 is by reference numerals 68 identified.

In 2 is the inventively proposed pressure control valve according to 1 shown in the closed state.

In the closed state of the pressure control valve 10 adjusts itself with reference numerals 58 identified leakage current. Because of in the cavity 14 the high-pressure accumulator 12 With high pressure stored fuel adjusts itself a leakage, starting from the cavity 14 through the throttle hole 56 of the second valve seat 52 the inlet throttle channel 44 flows in. Via the inlet throttle channel 44 becomes the control room 30 in the common valve insert 16 applied. Along the production-related adjusting guide gap 64 between the receiving bore for the intensifier 38 in the common valve insert 16 the leakage current flows 58 in the valve room 66 and from there via the second return channel 46 the common return 34 on the low pressure side of the present invention proposed pressure control valve 10 to. The size of the leakage current is negligible. The leakage current 58 flows on the low pressure side back to the fuel tank of the vehicle.

3 shows the inventively proposed two-stage pressure control valve in a state in which the realization of small flows, the first valve stage is activated.

As 3 it can be seen, is the first valve stage 20 ie the solenoid valve is activated. When the solenoid is energized 22 moves the valve member 36 on, so that the first ball-shaped closing element 26 the first valve seat 24 releases and the control room 30 consequently via the outlet throttle 28 relieved of pressure. It turns therefore a first leakage current 60 a, like in 3 located. The first leakage current 60 also flows through the throttle bore 36 of the second valve seat 52 , the inlet throttle channel 44 in the common valve insert 16 the control room 30 to and flows through the opened outlet throttle 28 and the first return channel 32 the common return 34 on the low pressure side of the pressure control valve 10 to.

In this in 3 illustrated state is the second valve stage 42 , ie the hydraulic valve is not yet actuated, as the pressure in the control room 30 not yet on the opening pressure, in which the piston-shaped pressure booster 38 opens, has sunk.

Im in 3 shown state can at very small flow through the appropriately sized outlet throttle 28 small flow rates can be realized, so that the system pressure in the high-pressure accumulator 16 can be regulated directly. The first valve stage 20 , ie the solenoid valve is active as long as the pressure in the control room 30 not below the opening pressure of the piston-shaped pressure booster 38 decreases.

3 shows that in the operating state shown there, the pressure in the control room 30 has not fallen so far that the piston-shaped pressure booster 38 auffahren, ie the second closing element 78 the second valve seat 52 not yet released. Accordingly, in the in 3 shown state, only the first leakage current 60 one, which - as outlined above - through the control room 30 and the first return channel 32 flows. At the same time the leakage current flows 58 starting from the cavity 14 the high-pressure accumulator 12 also via the throttle bore 56 , the inlet throttle channel 44 in the common valve insert 16 , the control room 30 , the first return channel 32 , the common return 34 the high-pressure accumulator 12 to.

4 shows the inventively proposed two-stage pressure control valve in a state in which both the first valve stage and the second valve stage of the pressure regulating valve is activated.

Starting from the state in 3 in which by activating the first valve stage 20 the pressure in the control room 30 sinks, shows 4 that with a progressive pressure reduction in the control room 30 with the outlet throttle open 28 the pressure in the control room 30 so far drops that the piston-shaped pressure booster 38 in the control room 30 moves and thus the second closing element 58 the second valve seat 52 - as in 4 shown - releases. As a result, fuel now flows out of the cavity 14 the high-pressure accumulator 12 over the Vordrossel 50 , the opened second valve seat 52 in the valve room 66 one. From this fuel flows through the second return channel 46 in the common valve insert 16 from and the common return 34 to. In the common return 34 unite accordingly, as shown in 4 , the leakage current 58 , the first leakage current 60 , which is activated at the first valve stage 20 flows out and the second leakage current 62 , which is open at the second valve stage 42 flows out, to a common leakage current, which is returned to the fuel tank of the vehicle.

At the in 4 The state shown is that which is within a second operating range of the pressure regulating valve proposed according to the invention 10 is present when a higher flow rate is needed to increase the pressure in the high pressure accumulator 12 to regulate.

From the representation according to the 3 and 4 it turns out that the second valve stage 42 then activated when the pressure in the control room 30 through the first valve stage 20 opened outlet throttle 28 so far has dropped that the pressure level in the control room 30 below the opening pressure of the piston-shaped pressure booster 38 has dropped - taking into account in the closing direction of the pressure booster 38 acting closing spring 40 - Which is added to the piston-shaped pressure booster.

As soon as the first valve stage 20 is reactivated, ie the first valve stage 20 - designed as a solenoid valve - the first closing element 26 back in the first valve seat 24 represents, there is a pressure build-up in the control room 30 as this is continuously due to the operating pressure level, which is in the cavity 14 the high-pressure accumulator 12 is upright, is charged. The pressure in the cavity 14 the high-pressure accumulator 12 lies over the throttle bore 56 and to this subsequent inlet throttle channel 44 always at the control room 30 on, so in this case with the outlet throttle closed 28 the pressure level rises. Once the pressure level in the control room 30 has risen so far that the opening pressure of the piston-shaped pressure booster 38 is reached and exceeded, moves the piston-shaped pressure booster 38 , supported by the closing spring 40 , in the closing direction of the second closing element 48 , This is thus in the valve funnel 70 of the second valve seat 52 put, so that the Vordrossel 50 , which is centric in the second valve seat 52 is formed, is closed. Once the second valve stage 42 is closed, only the leakage current 58 (see illustration according to 2 ) transported in the common return, which the manufacturing condition existing guide gap 64 between the lateral surface of the piston-shaped pressure booster 38 on the one hand and the extent of the piston-shaped pressure booster 38 receiving bore in the common valve core 16 owed.

By the inventively proposed pressure control valve 10 can be achieved in a compact design that the first valve stage 20 and the second valve stage 42 in one and the same valve insert 16 can be integrated. In this case, the first valve stage 20 , Preferably designed as a solenoid valve, are optimally designed at the first operating range of the pressure control valve with respect to the required flow rates to be realized, wherein the second valve stage 42 the inventively proposed pressure control valve 10 , designed as a hydraulic valve, in optimal

Be adapted to the displayed larger flow rates and the corresponding pressure level.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10231135 A1 [0001]

Claims (12)

Pressure control valve ( 10 ) for regulating the pressure in a high pressure accumulator ( 12 ) for a fuel injection system, characterized in that the pressure regulating valve ( 10 ) is carried out in two stages and a first valve stage ( 20 ) for a smaller flow within a first operating range of the pressure regulating valve ( 10 ) and another, second valve stage ( 42 ) for a larger flow within a second operating range of the pressure regulating valve ( 10 ). Pressure control valve ( 10 ) according to claim 1, characterized in that the first valve stage ( 20 ) as a solenoid valve and the second valve stage ( 42 ) is designed as a hydraulic valve. Pressure control valve ( 10 ) according to one of the preceding claims, characterized in that the smaller flow rate of the first valve stage ( 20 ) in a range <50 l / h and the larger flow of the second valve stage ( 42 ) is in a range up to 400 l / h. Pressure control valve ( 10 ) according to one of the preceding claims, characterized in that the first operating region of the pressure regulating valve ( 10 ) is characterized by flows below 50 l / h at pressures ≥ 3000 bar. Pressure control valve ( 10 ) according to one of the preceding claims, characterized in that the second operating region of the pressure regulating valve ( 10 ) is characterized by flow rates up to 400 l / h and low pressures between 150 bar and 500 bar. Pressure control valve ( 10 ) according to one of the preceding claims, characterized in that the first valve stage ( 20 ) a first closing element ( 26 ) comprising a control room ( 30 ) depressurized. Pressure control valve ( 10 ) according to the preceding claim, characterized in that the control room ( 30 ) a pressure booster ( 38 ) which in turn pressurizes a second closing element ( 48 ) of the second valve stage ( 42 ). Pressure control valve ( 10 ) according to the two preceding claims, characterized in that upon reaching and falling below an opening pressure level for the pressure booster ( 38 ) in the control room ( 30 ) the second closing element ( 48 ) of the second valve stage ( 42 ) a second valve seat ( 52 ) releases. Pressure control valve ( 10 ) according to one of the preceding claims, characterized in that the pressure booster ( 38 ) by a closing spring ( 40 ) is acted upon in the closing direction. Pressure control valve ( 10 ) according to one of the preceding claims, characterized in that the first valve stage ( 20 ) and the second valve stage ( 42 ) in a common valve core ( 16 ) are included. Pressure control valve ( 10 ) according to the preceding claim, characterized in that the common valve core ( 16 ) an inlet throttle ( 44 ) for filling the control room ( 30 ) and a first return channel ( 32 ) and a second return channel ( 46 ) in a common return ( 34 ) open at a low pressure side. Use of the pressure regulating valve ( 10 ) according to one of claims 1 to 11 to a high-pressure accumulator ( 12 ) (Common rail) of a fuel injection system for passenger cars or trucks.

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