EP1904732B1 - Device for generating a vacuum in a motor vehicle - Google Patents

Abstract

A device is provided for producing and/or augmenting a partial vacuum in a motor vehicle, in particular for operating a partial vacuum brake servo-unit. The device includes, but is not limited to a throttle unit, which has at least one throttle valve housing and a throttle valve which is arranged so as to be rotatable in an angle range in a throttle channel in the throttle valve housing for controlling a fluid flow in the throttle channel. The device also includes, but is not limited to means for producing and/or augmenting partial vacuum, the means being configured as partial vacuum augmentation means integrated into the throttle valve housing, which partial vacuum augmentation means act according to Bernoulli's principle in the manner of a sucking jet pump to produce an augmented partial vacuum for at least one brake servo-unit. The means are configured as at least one control bore extending through the throttle valve housing, wherein the control bore opens in the throttle channel in an opening to produce a partial vacuum in the control bore and the control bore is set in the drag direction at a setting angle α>0° measured with respect to the cross-sectional plane of the throttle channel.

Description

The invention relates to a device for generating and / or amplifying a negative pressure in a motor vehicle, in particular for operating a vacuum brake booster, comprising a throttle unit, which at least one throttle body and a throttle in a throttle body in an angular range rotatably arranged throttle valve for regulating a fluid flow in the throttle passage, wherein the device further comprises means for generating and / or amplifying a negative pressure, wherein the means are formed as integrated into the throttle body vacuum booster means, which act according to the principle of Bernoulli in the manner of a suction jet pump to an increased negative pressure for at least one To generate brake booster.

A generic device for generating negative pressure in a motor vehicle with an internal combustion engine is already versatile application. The provision of the negative pressure in motor vehicles is necessary in particular for the function of vacuum-supplied brake boosters. Herein, the difference between the atmospheric pressure and the negative pressure for enhancing the braking force on the brake cylinder is utilized. Safe operation of the brake booster and thus the brake system of the motor vehicle therefore always requires to store a sufficient negative pressure in the vacuum chamber of the brake booster by means of a check valve to ensure sufficient braking force in any driving situation. The quantity control element for the power control of the internal combustion engine generally regulates the intake air flow and thus the power of the internal combustion engine via a rotational adjustment of a throttle valve. Disadvantageous in terms of the possibility of a vacuum tap is in this principle of different power position of the internal combustion engine and depending on the driving situation different vacuum in the intake manifold. Especially in vehicles with comfort features such as automatic transmission and high-performance air conditioning in conjunction with an optimized with respect to the partial load throttle losses gasoline engine vacuum for a reliable supply of the brake system may not be enough. In particular, stop-and-go driving situations in the gradient at high ambient temperatures are to be considered here.

To improve the vacuum level, an intake air suction jet pump is sometimes provided in parallel with the throttle body. By means of the use of the corresponding part of the intake air flow as a propellant gas can be generated according to the law of Bernoulli as a result of the well-known principle of cross-sectional constriction and the associated increase in speed in a venturi increased negative pressure.

For the provision of negative pressure and electrically or mechanically driven vacuum pumps have been proposed, which, however, due to the multiple energy conversion in the motor vehicle with an internal combustion engine a poor overall efficiency. In addition, the vacuum pumps used as ancillary equipment cause considerable parts costs and lead to a higher susceptibility to failure of the entire system. Thus, the reliability of a pneumatic brake booster is impaired, this represents a significant security risk during operation of the motor vehicle.

In the DE 198 08 548 A1 a device for generating and / or amplifying the negative pressure in a pneumatic brake booster for the brake system of a motor vehicle driven by an internal combustion engine by means of a suction jet pump is proposed in which the suction jet pump is arranged in the exhaust system of the internal combustion engine and is used as propellant the exhaust gas mass flow of the internal combustion engine. Disadvantageous in this arrangement is the position of the device in the hot exhaust gas of the internal combustion engine, which severely limits the possible uses of various thermally unstable materials. In addition, the exhaust gas mass flow is proportional to the throttle position and engine speed dependent, so that at a closed throttle and thus a low charge air flow and the exhaust gas mass flow does not produce sufficient flow in each operating situation of the motor vehicle to ensure a sufficient negative pressure for the operation of the pneumatic brake booster.

The DE 195 03 568 A1 relates to a quantity-controlled internal combustion engine having a suction jet pump arranged in a bypass to the quantity control member or throttle valve for generating negative pressure of a servomotor, in particular a brake booster, wherein a blocking and / or throttle valve provided in the bypass upstream of the suction jet pump is arranged. With this structure is indeed synonymous with a small Fluid flow of the charge air sufficient vacuum generation possible, however, the arrangement has an external structure, which is arranged in addition to acting as a throttle unit quantity control member, and further individual parts which must be integrated in the engine compartment. In addition, a locking and / or throttle valve is required, which must be electrically controlled disadvantageously.

In the DE 196 22 378 A1 is proposed a throttle body for an internal combustion engine of a motor vehicle with a throttle valve adjustable in a channel, wherein the region of the channel is bridged by a throttle valve of a bypass channel. In the bypass channel is seen in the flow direction, first an electrically switchable valve and then a Venturi tube arranged. In the entrance area of the Venturi tube a vacuum device for a brake booster is connected. This arrangement also requires an external structure to the throttle body, which must be integrated in the engine compartment. In addition, due to the varying fluid flow in the channel, a valve is required, which must be controlled via an actuator.

In these known methods, the problem arises that external Saugrohranordnungen are required, which must be integrated in the engine compartment, which electrically or mechanically have valves that require electrical control and are also costly and lead to increased susceptibility to failure of the system.

From the FR 834 168 A a device is known in which external arrangements and electrical controls are not required to generate a negative pressure. The disadvantage here, however, is a secure vacuum generation and In particular, a vacuum improvement is not possible, which is very important in particular when operating vacuum brake booster.

It is therefore the object of the present invention to provide a device for generating and / or amplifying a negative pressure in a motor vehicle, by means of which the negative pressure within the fluidic laws is improved for each idling or thrust operating point of the vehicle or the internal combustion engine, so that vacuum brake booster can be operated such that at any time an increased brake power assistance is available.

This object is achieved on the basis of a device for generating negative pressure according to the preamble of claim 1 in conjunction with its characterizing features. Advantageous developments of the invention are specified in the dependent claims.

The invention includes the technical teaching that the means are formed as at least one extending through the throttle body control bore, the control bore opens in the throttle passage in an orifice to generate a negative pressure in the control bore, and that the throttle has a thickening on the control bore side to increase the negative pressure over an enlarged flap opening angle range.

This solution has the advantage that the means by integration into the throttle body do not appear as individual parts, and thus need not be separately integrated into the engine compartment. It eliminates the need to provide electrically or via a mechanical coupling to the internal combustion engine driven vacuum generating or amplifying devices. The tap of the negative pressure takes place directly on the integrated in the housing of the throttle flow geometry, which uses the principle of operation of a suction jet pump. In this case, a throttle unit in internal combustion engines, which are controlled according to the quantity principle (such as the gasoline engine), already exists. Due to the mechanical design of the means for generating and / or amplifying the negative pressure, the negative pressure within the fluidic laws can be improved for each idling or thrust operating point of the vehicle or the internal combustion engine, in particular to operate a pneumatically operated vacuum brake booster such that at any time an increased brake power assistance is available. The vacuum connection takes place on the housing of the throttle unit, wherein the vacuum supply of the brake booster only a hose or pipe connection with a check valve is necessary, which is easily connected to the vacuum port. This connection can be present either in addition to the existing vacuum supply, or the conventional vacuum supply to the intake manifold can be omitted entirely, if sufficiently large flow cross sections can be displayed. In this case, no additional component is necessary. Furthermore, eliminates an electrical control of the vacuum generating or amplifying means. The overall system of negative pressure generation can thus be characterized in that the generation of the negative pressure takes place exclusively via the control bore in the throttle body and other negative pressure supplies omitted.

Preferably, the means for generating and / or amplifying a negative pressure are designed as throttle valve angle range-dependent negative pressure boosting means in order to generate an increased negative pressure in a certain range of the throttle valve opening. The means for generating negative pressure are such that the negative pressure tap takes place in this throttle angle range in the zone of the highest flow velocity.

Advantageously, the means are designed as at least one control bore extending through the throttle body, wherein the control bore opens in the throttle passage in an orifice to generate a negative pressure in the control bore. The arrangement of the control bore is suitably inclined at an angle relative to the flow direction. The angle α must have a value greater than 0 ° in order to avoid a congestion effect. Advantageously, this control bore opens in the downstream in the flow direction half of the throttle channel. This has the advantage that at idle without additional loads with minimal flap opening of the normal Saugrohrunterdruck applied. Accordingly, under certain circumstances, the previous Saugrohrunterdruckanschluss the brake booster can be replaced by the connection to the control bore. Optionally, it can be examined at which point on the damper perimeter line (directly adjacent to the damper axis or farther from the axis, in an extreme case offset 90 °), the orifice is to be positioned to extend the brake vacuum boost over a larger angular range of throttle opening. The design criteria are, firstly, the maximum possible flow rate (corresponds to the maximum increase in negative pressure) and, secondly, the throttle valve angle range, via which the negative pressure increase can be used. As near-idle operation of the engine, speeds of approx. 800rpm to 1000rpm. Further measures for using the maximum flow velocity can be seen in an extension of the control bore in a projecting into the throttle channel head tube and / or in structures in the throttle body, which extend into the flow cross section, wherein the free end of the head tube or the bore in Area of maximum flow velocity opens.

A further measure improving the invention provides that the throttle valve has a thickening on the control bore side in order to achieve an increase in the negative pressure over an enlarged valve opening angle range. The throttle plate has a disc shape in a known manner, wherein the disc on the side of the control bore has a half-sided thickening, which in turn can cause a narrowing of the flow and thus a reduction of the static pressure according to the Bernoulli principle in the area concerned.

The control bore preferably opens into the throttle passage in an area at least partially swept by the throttle flap.

According to a further embodiment of the invention, it is proposed that the means for generating and / or amplifying a negative pressure are designed as at least one throttle bore arranged as a bypass to the throttle channel and in the throttle body, in order to produce an accelerated fluid flow in the throttle bore. Thus, the flow of the intake air used as propellant gas is passed through a separate throttle bore, wherein the throttle channel and the throttle bore extend parallel to at least a partial length of the throttle body. According to this embodiment lies in modified form, a separate Saugstrahlpumpenanordnung, wherein this invention is integrated in the throttle body.

Regardless of the design of the throttle channel, the throttle bore has a flow restriction in the manner of a Venturi tube in order to accelerate the fluid flow in the throttle bore. Thus, the control bore can open in the region of the flow constriction in the throttle bore, to thereby produce a further increase in the negative pressure.

Fig. 1:

eine perspektivische Ansicht einer Vorrichtung zur Erzeugung und/oder Verstärkung eines Unterdruckes mit einer Drosseleinheit;

Fig. 2:

eine Schnittansicht der Drosseleinheit, wobei die Steuerbohrung in den Drosselkanal mündet; und

Fig. 3:

eine Schnittansicht der Drosseleinheit, wobei diese eine Drosselbohrung aufweist und die Steuerbohrung in die Drosselbohrung mündet.

Further measures improving the invention are specified in the dependent claims or will be described in more detail below together with the description of preferred embodiments of the invention with reference to FIGS. It shows:

Fig. 1:

a perspective view of a device for generating and / or amplifying a negative pressure with a throttle unit;

Fig. 2:

a sectional view of the throttle unit, wherein the control bore opens into the throttle channel; and

3:

a sectional view of the throttle unit, which has a throttle bore and the control bore opens into the throttle bore.

In the Fig. 1 illustrated device 1 comprises a throttle unit 2, which has a throttle body 3, through which a throttle channel 4 extends. The throttle unit 2 is arranged in the intake air tract of the internal combustion engine (not shown), wherein the throttle duct 4 forms a connection between the hose or pipe connection of the air filter and the air collector of the internal combustion engine. In the throttle channel 4, a throttle valve 5 is rotatably arranged, through which with a rotation of the air mass flow of the intake air can be changed. The throttle valve 5 is shown in the illustrated embodiment in a substantially closed position, so that the air mass flow of the intake air assumes a low value. The throttle body 3 is made in one piece, in this case fittings, mounting areas, mounting holes and the like are formed on the throttle body 3 in addition to other components. Through the throttle body 3, a control bore 6 extends, which opens on the one hand in the throttle channel 4 and on the other hand merges into a pipe section to which a vacuum hose is connectable. This - not shown vacuum hose - forms a connection between the arranged in the throttle body means for generating negative pressure and a pneumatic Brake booster or other functional units, which represent a vacuum consumer. On the rear part of the throttle body an electromechanical control 7 is arranged, via which in particular the control of the throttle valve 5 takes place. The electrical connection of the controller 7 via a contact means 8, which allows an electrical connection to the central control electrics of the motor vehicle.

FIG. 2 shows a sectional view of a first embodiment of the device 1, comprising a throttle unit 2, wherein the control bore 6 opens into the throttle channel 4. The mouth 9 is arranged directly in the region in which the throttle valve 5 is adjacent to the throttling passage wall 11 when idling. The flow restriction increases the flow rate of the air mass flow of the intake air, which according to the Bernoulli's theorem, the static pressure decreases, so that a negative pressure arises, which continues in the control bore 6. So that the air mass flow moving in the flow direction 12 does not press into the control bore 6, it is employed in the towing direction under an angle of attack α> 0 ° measured to the cross-sectional plane of the throttle channel 4.

FIG. 3 is another embodiment of the device 1 again, which is shown in a sectional view through the throttle unit 2, which has a control bore 6, which opens into a throttle bore 10. The throttle bore 10 is arranged in the throttle channel 4 and extends in the flow direction 12, so that a portion of the intake air is diverted from the throttle channel 4 and the throttle bore 10 flows through. The throttle bore 10 has a flow constriction 13 in the manner of a Venturi tube, whereby at a subcritical pressure ratio across the throttle acceleration the intake air flow in the flow constriction 13 can be reached. The control bore 6 opens in the region of the flow constriction 13 in the throttle bore 10, so that here too a stronger suction effect can be exploited. When the throttle valve 5 is closed or almost closed, the air mass flow through the throttle passage is minimized, and the throttle bore 10 acts as a bypass, in which an increased flow velocity prevails, and an increased negative pressure can be tapped via the control bore 6 in comparison to the intake manifold vacuum.

LIST OF REFERENCE NUMBERS

1

contraption

2

restrictor

3

throttle body

4

throttle channel

5

throttle

6

control bore

7

control

8th

contact means

9

muzzle

10

throttle bore

11

Drosselkanalwandung

12

flow direction

13

flow constriction

α

angle of attack

Claims (10)

1. An apparatus (1) for generating and/or boosting a vacuum in a motor vehicle, especially for operating a vacuum brake booster, comprising a throttle unit (2) which comprises at least one throttle body housing (3) and a throttle (5) for controlling a fluid flow in the throttle passage (4), which throttle is arranged in a rotatable manner in an angular range in a throttle passage (4) in the throttle body housing (3), with the apparatus (1) further comprising means for generating and/or boosting a vacuum, with the means being arranged as vacuum boosting means which are integrated in the throttle housing (3) and which act according to Bernoulli's principle in the manner of a jet pump in order to generate a boosted vacuum for at least one brake booster, with the means being arranged as at least one control bore (6) extending through the throttle body housing (3), and with the control bore (6) in the throttle passage (4) opening into an orifice (9) in order to generate a vacuum in the control bore (6), characterized in that the throttle comprises an enlargement on the side of the control bore in order to achieve an increase in the vacuum via an enlarged angular range of the throttle opening.
2. An apparatus (1) according to claim 1, characterized in that the means for generating and/or boosting a vacuum are arranged as vacuum boosting means which are dependent on the angular range of the throttle in order to generate an increased vacuum in a specific region of the throttle opening.
3. An apparatus (1) according to claim 1 or 2, characterized in that the control bore (6) opens into the throttle passage (4) in the region in which the fluid flowing through the throttle passage (4) has a maximum through-flow speed at operation of the engine close to idle running with additional loads.
4. An apparatus (1) according to claim 3, characterized in that the control bore (6) opens into the throttle passage (4) in the half of the throttle passage (4) which is disposed downstream in the direction of through flow.
5. An apparatus (1) according to claim 1 to 5, characterized in that the control bore (6) opens into the throttle passage (4) in a region which is covered by the throttle (5) at least partly by the angular range of the throttle rotation.
6. An apparatus (1) according to claim 1 and 2, characterized in that the means for generating and/or boosting a vacuum are arranged as at least one throttle bore (10) arranged as a bypass to the throttle passage (4) and in the throttle body housing (3) in order to produce an accelerated fluid flow in the throttle bore (10).
7. An apparatus (1) according to claim 6, characterized in that the throttle bore (10) comprises a flow constriction (13) in the manner of a venturi tube in order to accelerate the fluid flow in the flow constriction (13).
8. An apparatus (1) according to claim 7, characterized in that the control bore (6) opens into the throttle bore (10) in the region of the flow construction (13) in order to produce a vacuum herein.
9. The use of an apparatus according to one of the claims 1 to 8 for generating and/or boosting a vacuum for operating one or several devices in a motor vehicle which are supplied with vacuum.
10. The use according to claim 9, characterized in that the device is a vacuum brake booster.

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