EP1607590A2 - Engine with hydraulic camshaft phasing device - Google Patents

Abstract

The device includes a hydraulic fluid system with at least one hydraulic valve and connected to two pressure chambers (12,13) pressurized or depressurized with hydraulic fluid though hydraulic lines. The two pressure chambers are separated within the work spaces (9) of a drive wheel (3) by the blades (11) of a rotor (5). The rotor is rotatable relative to a stator (4), and attached to the camshaft. The drive wheel couples the stator to the crankshaft.

Description

Field of the invention

The invention relates to an internal combustion engine having a hydraulic device for adjusting the rotational angle of a camshaft relative to a crankshaft, comprising:
a rotor with wings arranged thereon, which is rotatably connected to the camshaft and a stator which is non-rotatably connected to a driven by the crankshaft drive wheel, wherein on both sides of the wing pressure chambers are provided, which are pressurizable or emptying via a hydraulic system with hydraulic fluid.

Background of the invention

Such a device is generic from DE 199 63 094 A1 previously known. This trained as so-called Flügelzellenverstelleinrichtung Device consists essentially of one with a crankshaft Internal combustion engine in drive connection stationary stator, the rotation with a drive wheel is connected, and a rotationally fixed to a camshaft the internal combustion engine connected rotor. The stator has a formed by a hollow cylindrical peripheral wall and two side walls Cavity in which by boundary walls hydraulic work spaces be formed. The rotor has radially on the circumference of its hub each a working space of the drive wheel extending wings, which the work spaces in two oppositely acting hydraulic pressure chambers divide. The pressure chambers of each working space are against each other sealed and cause with selective and simultaneous pressurization with hydraulic fluid from a hydraulic fluid circuit, in usually with engine oil, a pivoting movement or a fixation of the rotor relative to the stator and thus the camshaft relative to the crankshaft.

Many of the newer rotational angle adjustment devices are in the drive system the camshaft, in the so-called timing gear, integrated. It will be transmitted mechanical vibrations during engine operation in the Crank drive, in the timing drive or valve train arise. Is the drive wheel with the crankshaft, for example, by a belt or a chain in Actively connected, the device also converts a translational movement into a rotational movement. In this conversion will be additional generates mechanical vibrations.

As the power transmission in devices for angular displacement with vane principle is done by hydraulically clamped wings, is the hydraulic fluid circuit the internal combustion engine in the power transmission for the Integrated drive of the camshaft. Due to air entrapment in the Hydraulic fluid and internal or external oil leakage is only a limited Torsional rigidity between the drive and output side on the Device possible. This allows the mentioned mechanical vibrations transferred to the hydraulic fluid circuit of the internal combustion engine become. In case of unfavorable arrangement of the device in the control drive can As a result, high pressures or pressure peaks occur that are above 200 bar.

In particular, if several devices for the rotation angle adjustment, for example through a chain drive communicate with each other and can be out of phase, can sag the chain. Adjust the devices then again out of phase, but in the opposite direction, It comes to sudden high chain tension, over the stators in the Pressure chambers are introduced to the hydraulic fluid and there the Cause pressure peaks. They are the higher, the larger the rotation angle difference of the devices. Even with unfavorable phase angle of the camshafts to each other, for example by increasing overlap of the valve curves, can cause sudden chain tension: Is located to Example of intake cams in the area of the leading edge and the exhaust cams in the area of the expiration flank, forces arise, their direction opposite is set, which can then cause the pressure peaks again.

These pressure peaks are for both the device and for the internal combustion engine harmful. First, they reduce the durability of the components, which have direct contact with the hydraulic fluid circuit, on the other hand, they influence the function of hydraulically controlled systems in this hydraulic fluid circuit, such as a hydraulic Chain tensioner, in a negative way.

In DE 198 37 693 A1 is proposed to solve this problem, the Hydraulic fluid connections of the pressure chambers each one in the direction Hydraulic pump upstream check valve. Thereby can but only pressure spikes are eliminated due to camshaft alternating torques result and are not high frequency. It also needs There additional installation work, other components in the hydraulic fluid circuit to integrate.

Object of the invention

The invention is therefore based on the object in a hydraulic fluid circuit provided with a device for rotational angle adjustment Internal combustion engine to reduce pressure fluctuations as much as possible and thus in particular to eliminate pressure peaks.

Summary of the invention

According to the invention this object is achieved by the features of the characterizing Part of claim 1 solved. Accordingly, in the hydraulic fluid circuit between the device for rotational angle adjustment and the associated Hydraulic valve arranged a volume storage. This one stands out characterized in that its volume is variable and solely by the pressure in the Hydraulic fluid circuit is determined. Increases then suddenly the Pressure in the hydraulic fluid circuit, there is an increase in the hydraulic fluid available volume through the volume memory. This volume release counteracts the pressure change. In the reverse In the case, the volume accumulator reduces this for the hydraulic fluid in the hydraulic fluid circuit available volumes. Is the inertia of the Volume memory low, it can also be generated by a pressure peak Pulsing counteract as a vibration damper.

1. den Kolben im Sackloch axial zu führen,

2. das Federelement aufzunehmen und

3. dessen axialen Weg zu begrenzen, indem es am Boden des Sacklochs aufsetzt.

The volume storage is designed, for example, as a pressure-spring-controlled piston accumulator. It consists in this case of a piston which is positioned in a blind hole, and an axially acting spring element. But it would also be conceivable a rotationally acting spring element. The piston is composed of a piston head, which can be acted upon by hydraulic fluid, and constructed from a piston skirt. The function of the piston skirt is to

1. axially guiding the piston in the blind hole,

2. to absorb the spring element and

3. limit its axial travel by resting on the bottom of the blind hole.

The spring element, for example, designed as a helical spring is located in the piston and faces the open side of the piston. By Selection of a spring element with a system-determined spring rate can set a suitable opening pressure at which the piston gets the opportunity to move axially towards the bottom of the blind hole shift and thus increase the volume of the hydraulic fluid system.

To limit the leakage behind the piston, the blind hole be executed as a clearance. The leakage, which despite the fit located behind the piston is discharged through a vent hole, so that the way of the piston is not limited early. Instead of a vent hole provided, the space behind the piston can also by means of a Seal to be sealed.

At a pressure drop in the hydraulic fluid system, the spring element tries under the opening pressure of the piston accumulator, the piston in the direction Hydraulic fluid system to press and may be a hydraulic fluid line close. To prevent this undesirable effect and to bias the spring according to the opening pressure, becomes a forward-acting path limiter in the hydraulic fluid system brought in. This can be an additional component, for example is arranged in the hydraulic fluid line or in the volume memory, but can also be done by a suitable design of the piston crown. The bias is chosen so that in each case a flow in the Hydraulic fluid system is possible, even if there is no pressure in the system.

Particularly advantageous is an arrangement of the volume memory in the device for the rotation angle adjustment itself, because there the pressure peaks in the hydraulic fluid be initiated. Firstly, they will be as fast as possible balanced. Second, as few components as possible, through the hydraulic fluid system be cared for, affected. thirdly Saves an integrated solution space and reduces installation costs.

In order to simultaneously reduce the number of components, the invention continues proposed, a locking unit of the device, which at insufficient pressure in the hydraulic fluid system, the device in one Fixed position fixed, at the same time to use as a volume storage. Because locking units in all modern devices for angular adjustment exist, manufacturing steps can be saved or eliminated.

Is in the device, however, not enough space available, can further volume memory in the hydraulic fluid lines, which to the Pressure chambers lead, be arranged.

The volume accumulator can also act as a bubble or as a membrane reservoir will be realized. Both types of memory serve as well as the piston accumulator in addition, the volume for the hydraulic fluid in the hydraulic fluid system to increase, so as to reduce pressure fluctuations. As the bubbles or Membrane memory supporting element can be any element, the springs are used. The main advantages of these solutions the piston spring accumulator are in their faster response. This can be cached with a piston spring accumulator a larger volume.

The membrane of a membrane memory has a low inertia a piston spring storage solution. This means significantly higher vibration frequencies possible. Due to their frequency complementary behavior the piston spring accumulator is particularly suitable combination of these two Solutions: Most high-frequency vibrations are low Amplitude and can be absorbed well through a membrane. The lower frequency vibrations have a larger amplitude, which a larger compensating volume requires that with a piston spring accumulator can be better realized. Due to the lower frequency is one in comparison To the membrane slower response here is not a disadvantage.

Even a bubble memory reacts very quickly to pressure changes. Its efficiency reaches almost 100%, and it works virtually smoothly and without inertia.

The inventively designed volume storage so dynamic Pressure changes in the hydraulic fluid system caught and also reduces any pulsation of the volume flow. This will be an improvement in the reliability of the device for adjusting the rotational angle and other hydraulic systems in the internal combustion engine. In addition, the durability of seals and other components elevated.

Furthermore, by choosing a suitable bias voltage, a reserve volume be created in the hydraulic fluid circuit, the short term one increased hydraulic fluid demand, for example, by power peaks is caused, can cover. This results in a faster Responsiveness, and higher start-up accelerations are possible because in addition to the hydraulic fluid volume of the device pump Volume of the volume memory is available.

Brief description of the drawings

Figur 1 a

einen Längsschnitt einer hydraulisch wirkenden Vorrichtung zur Drehwinkelverstellung,

Figur 1b

einen Querschnitt der Vorrichtung aus Figur 1 längs der Achse Ib-Ib,

Figur 2

einen Querschnitt eines Volumenspeichers in Kolbenform,

Figur 3a

eine perspektivische Darstellung eines Flügels einer Vorrichtung zur Drehwinkelverstellung mit einem integrierten Kolbenfederspeicher,

Figur 3b

einen Querschnitt des Flügels aus Figur 3a,

Figur 4

einen Längsschnitt eines Volumenspeichers mit elastischen Wänden.

The invention will be explained in more detail below with reference to five exemplary embodiments. The accompanying drawings show:

FIG. 1 a

a longitudinal section of a hydraulically acting device for adjusting the rotational angle,

FIG. 1b

a cross-section of the device of Figure 1 along the axis Ib-Ib,

FIG. 2

a cross section of a volume accumulator in piston shape,

FIG. 3a

a perspective view of a wing of a device for adjusting the rotational angle with an integrated piston spring accumulator,

FIG. 3b

a cross section of the wing of Figure 3a,

FIG. 4

a longitudinal section of a volume storage with elastic walls.

Detailed description of the drawings

FIGS. 1 a and 1 b show a device 1 for adjusting the rotational angle between a crankshaft not shown and also not shown Camshaft out. This device 1 is as Rotationskolbenverstelleinrichtung at the drive end of the cylinder head, not shown the internal combustion engine mounted camshaft attached and in principle designed as a hydraulic actuator, depending on different Operating parameters of the internal combustion engine by a hydraulic valve. 2 via hydraulic fluid lines 19 of a hydraulic fluid system 32 is controlled.

Furthermore, it is apparent that the device 1 consists essentially of a with the crankshaft via a drive wheel 3 in drive connection Stator 4 and a rotatably connected to the camshaft rotor 5, wherein the rotor 5 is pivotally mounted in the drive wheel 3 and with this in Power transmission connection is. The drive wheel 3 has a through a hollow cylindrical peripheral wall 6 and two side walls 7, 7 'formed Cavity, in which directed by the longitudinal central axis of the device 1 radial reference walls 8, 8 'evenly distributed hydraulic working spaces 9 are formed. The rotor 5 has accordingly on the circumference of his Wheel hub 10 equally circumferentially distributed and each in a work space 9 of the drive wheel 3 extending wings 11, which the work spaces Divide 9 into each of an A-pressure chamber 12 and a B-pressure chamber 13, in the case of selective or simultaneous pressurization with a Hydraulic fluid against a pivoting movement or fixation of the rotor 5 the stator 4 and thus a rotational angle adjustment or a hydraulic Causing clamping of the camshaft relative to the crankshaft.

Also, a locking element 14 can be seen, which is to avoid a from the alternating torques of the camshaft resulting Anschlagklapperns of the rotor 5 at the start of the internal combustion engine is used. The locking element 14 is below one required for adjustment Hydraulic fluid pressure in a preferred base position within its Adjustment range mechanically coupled to the stator 4. It's as sleeve-like Cylindrical pin formed and in a continuous axial bore 15 in arranged the wheel hub 10 of the rotor. A locking spring element 16, which on the one hand on the back of the locking element 14 and on the other hand on a likewise inserted into the axial bore 15 counter-holder is capable of, within a receptacle 18 in the camshaft facing away Side wall 6 of the stator 4, the locking element 14 to move. The A-pressure chambers 12 and B-pressure chambers 13 are through Hydraulic fluid lines 19 connected to the hydraulic valve 2. In the Hydraulic fluid lines 19, a volume memory 20 is arranged.

FIG. 2 shows a cross section of a piston accumulator 34 Volume memory 20. It adjoins formed as a blind hole 21 directly to the Hydraulic fluid line 19 on. In the blind hole 21, a piston 22 with arranged a piston skirt 23, wherein the piston skirt 23, the piston 22nd in the blind hole 21 leads axially, a spring element 24 receives and by his Form limits the axial spring travel, while at large deflection of the Spring element 24 at the bottom of the blind hole 21 touches. A change the pressure in the hydraulic fluid line 19 therefore causes a deflection of the spring element 24, which is a change of the hydraulic fluid available volume. The volume change counteracts the pressure change. The selection of a suitable spring element 24 or the arrangement of a Wegbegrenzers 33 put it sure that the hydraulic fluid line 19 is never completely closed. Around the oil leakage from the hydraulic fluid line 19 behind the piston 22 to limit, the blind hole 21 is designed as a clearance fit. The oil leakage, which is despite the fit behind the piston, for example removed via a vent hole 25. This will be the way of the Piston 22 not limited early.

The volume memory 20 may be formed as a separate unit, or it is integrated into the locking element 14. In this case, the axial bore corresponds 15 the blind hole 21 and the piston 22 the locking element 14th

FIGS. 3 a and 3 b show a volume accumulator integrated in the wing 11 20. The wing 11 is formed in two parts and has a passage opening 29, wherein within the wing 11 in the radial direction at least one Cavity 27 is formed in the two designed as slices piston 22nd are used so that the piston 22, the passage opening 29 to both Close sides. The pistons 22 are interconnected by disc springs 30 and on the other, outer side by the respective edge region 31 of the wings 11 supported. Instead of disc springs 30 can also another, elastic element can be used. At a pressure increase in one of the two chambers 12, 13 in the device 1, the piston 22 is displaced and thus causes a volume change of the chamber. The repressed Air in the cavity 27 is through a vent hole 25, which with the cavity 27 is connected, as well as a potential hydraulic fluid leakage dissipated.

FIG. 4 shows a volume accumulator 20, which acts as an elastic tube 26 trained diaphragm accumulator is realized. In this education is in the Hydraulic fluid lines 19 a cavity 27 is introduced, in which the elastic Tubes 26 are arranged. These are made of plastic or metal. In this embodiment, the elastic tube 26 takes over the same function the piston 22 and the spring element 24 of the piston accumulator design. When increasing the pressure in the hydraulic fluid line, air and a possible oil leakage through vent holes 25 from the cavity 27th escape. The spring stiffness of the system is determined by the design of the elastic Pipe 26 set. Conveniently, the membrane is glued or trapped.

Instead of in the form of an elastic tube 26 which springs, the membrane 28 can also be shaped as a bubble and the function as a working component of a assume the hydraulic fluid line 19 arranged bladder accumulator. The gas-filled bladder is fixed in place, and its extent depends after the pressure surrounding them.

LIST OF REFERENCE NUMBERS

1

Device for adjusting the angle of rotation

2

hydraulic valve

3

drive wheel

4

stator

5

rotor

6

Hollow cylindrical peripheral wall

7,7 '

Side wall

8,8 '

Radial boundary wall

9

Hydraulic workspace

10

wheel hub

11

wing

12

A pressure chamber

13

B-pressure chamber

14

locking element

15

Continuous axial bore

16

Locking spring element

17

(not occupied)

18

admission

19

Hydraulic fluid line

20

volume storage

21

blind

22

piston

23

skirt

24

spring element

25

vent hole

26

elastic tube

27

cavity

28

membrane

29

Through opening

30

Belleville spring

31

Edge area of the wings

32

Hydraulic fluid system

33

travel limiters

34

piston accumulators

Claims (11)

Internal combustion engine with a hydraulic device (1) for adjusting the rotational angle of a camshaft relative to a crankshaft, comprising:
a rotor (5) having vanes (11) disposed thereon and non-rotatably connected to the camshaft, a stator (4) non-rotatably connected to a drive wheel (3) driven by the crankshaft, both sides of the vanes (11) A Pressure chambers (12) and B pressure chambers (13) are provided which can be pressurized or emptied via a hydraulic fluid system (32) with at least one hydraulic valve (2) by hydraulic fluid lines (19) with hydraulic fluid, characterized in that between the device ( 1) and the hydraulic valve (2) a volume memory (20) is arranged. Apparatus according to claim 1, characterized in that the volume memory (20) in the device (1) is arranged for the rotation angle adjustment. Apparatus according to claim 1, characterized in that the volume memory (20) is designed as a membrane memory. Apparatus according to claim 1, characterized in that the volume accumulator (20) is designed as a bladder accumulator. Apparatus according to claim 1, characterized in that the volume accumulator (20) as a pressure spring-controlled piston accumulator (34) is formed, which consists of at least one piston (22) and a spring element (24). Apparatus according to claim 5, characterized in that the spring element (24) is biased. Apparatus according to claim 5, characterized in that on the side facing away from the hydraulic fluid system (32) side of the piston (22) a vent hole (25) is arranged. Device according to claim 5, characterized in that a path limiter (33) delimiting the travel of the spring element (27) in the direction of the hydraulic fluid system (32) is arranged in the volume accumulator (20) or in the hydraulic fluid system (32). Apparatus according to claim 1, characterized in that the volume memory (20) in the wing (11) is arranged. Apparatus according to claim 9, characterized in that the volume memory (20) is supported by disc springs (34) to the edge region (31) of the wings (11). Internal combustion engine with a hydraulic device (1) for adjusting the rotational angle of a camshaft relative to a crankshaft, comprising:
a rotor (5) having vanes (11) disposed thereon and rotatably connected to the camshaft; a stator (4) rotatably connected to a drive wheel (3) driven by the crankshaft; a locking member (14) connecting the Rotor (5) relative to the stator (4) can fix, on both sides of the wing (11) A-pressure chambers (12) and B-pressure chambers (13) are provided, which via a hydraulic fluid system (32) with at least one hydraulic valve (2) be pressurized or emptied by hydraulic fluid lines (19) with hydraulic fluid, characterized in that a volume memory (20) in the locking element (14) is integrated.

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