WO2005050016A1

WO2005050016A1 - Axial piston compressor, in particular for the air conditioning system of a motor vehicle

Info

Publication number: WO2005050016A1
Application number: PCT/EP2004/011113
Authority: WO
Inventors: Otfried Schwarzkopf
Original assignee: Valeo Compressor Europe Gmbh
Priority date: 2003-11-19
Filing date: 2004-10-05
Publication date: 2005-06-02
Also published as: ATE390560T1; DE10354038B4; EP1692396A1; JP2007511702A; DE502004006690D1; EP1692396B1; DE10354038A1

Abstract

The invention relates to an axial piston compressor, in particular for the air conditioning system of a motor vehicle. Said compressor comprises a housing and a compressor unit, which is situated in the housing and operated by a drive shaft (104), for drawing in and compressing a coolant. The compressor unit comprises pistons (118) that are displaced axially back and forth in a cylinder block and an adjustable plate that drives the pistons, rotates with the drive shaft (104) and is configured as a swash or wobble plate or pivoting ring (107). The adjustable plate is constructed and dimensioned by the definition of the geometry and/or mass and/or centre of mass in such a way that its torque MSW as a result of the deviation torque Iyz, where MSW = Iyz * O2, i.e. the torque as a result of the mass inertia and the centre of mass of the adjustable plate, together with the torque Mk,ges as a result of the masses that have been displaced in a translatory manner, (in particular the pistons and optionally including the sliding blocks (121, 122), piston rods or similar), cause an increase in the tilt angle and thus an increase in the delivery output in the small tilt angle range in the event of an increase in speed and a constant pressure differential ?p between the high and low pressure sides and that the tilt angle is reduced, thus reducing the delivery output, once a limiting tilt angle agrenz has been exceeded, where Msw = Mk,ges, in the event of an increase in speed and a constant pressure differential.

Description

Axial piston compressors, in particular compressors for the air conditioning system of a motor vehicle

description

The invention relates to an axial piston compressor, in particular a compressor for the air conditioning system of a motor vehicle, of the design as a swivel or swash plate compressor with a swash plate device which is adjustable in its inclination and driven by the machine shaft.

The following patent applications relating to the prior art can be mentioned:

- EP 1172557 A2,

- DE 19514748 C2,

- EP 0809027, - DE 19839914,

- EP 99953619 and

- US 2002/0038600.

The first two publications mentioned primarily deal with the swashplate (swashplate) and its connection to the shaft (tilting mechanism of the swashplate) and the inertia of the swashplate.

A two-part support device is known from EP 1 172 557 A2, which simultaneously transmits the torque between the shaft and the swash plate as a driver. The first driver part fastened to the machine shaft, which is designed as a bearing in the form of a receiving bore, is arranged at a considerable distance next to the swivel plate, and a second, in the first jointly engaging driver part is designed as a lateral extension of the swivel plate. The first as well as the second driver part are available in pairs. Usually the bearing clearance of a driver and its bearing part is somewhat larger in order to lead in a more defined manner and to avoid overdetermination or a double fit. The consequence of this is that such a compressor cannot be operated independently of the speed, ie has a defined preferred direction of rotation.

The center of gravity distant from the tilt axis causes an unbalance, since the engine can only be balanced for a (preferably) medium swash plate tilt angle.

The swash plate, which has a thickened hub part, has a relatively large moment of inertia due to its "lateral extension" with a center of gravity far away from the tilt axis, so that a sudden change in the rotational speed with corresponding inertia leads to an inclination adjustment of the swash plate. Furthermore, the center of gravity significantly determines the control behavior, and in such a way that the compressor regulates strongly, i.e. The inertia forces of the swash plate and their center of gravity cause a moment of deviation that causes the translatory inertia forces (e.g. through the pistons and sliding blocks).

Such a design has been implemented in commercially available compressors which have the following essential properties:

- The mass moment of inertia of the swash plate causes a moment which is greater than the moment generated by the mass forces of the pistons.

- A center of gravity that lies outside the tilt or pivot point of the swashplate also supports this effect.

With regard to this type of compressor, which represents the typical design of a swash plate compressor, it should be noted that the mass of such a swash plate cannot be increased arbitrarily in order to change the control behavior. The reason for this is that in the compressors of the type described, the center of gravity of the swash plate is generally at a clear distance from the swivel joint of the swash plate. This construction is essentially due to the fact that the swash plate is in addition to a suitable guide on the Shaft must be coupled or "steered" with the shaft or a component connected to the shaft via an adjusting mechanism.

The aforementioned distance from the center of gravity of the swash plate and the swivel joint of the swash plate leads to an imbalance in the engine, in particular as a function of the swash plate tilt angle.

In DE 195 14 748 C2, the center of gravity of a swash plate is specifically used in order to provide a deviation torque even at the smallest tilting angles (e.g. at 0 °), which "regulates" the swash plate. This avoids the problem that the compressor can no longer be started (regulated) at a very small tilt angle, since the pressure difference required for this can no longer be produced due to the piston stroke being too small. The publication therefore aims in particular at operating the compressor without a clutch. In this operating mode, the compressor is also supplied with speed in the "Air conditioning off" state. As a result, the compressor always requires a certain torque, which must be minimized.

When the compressor starts ("air conditioning on"), the compressor should be able to regulate. For this purpose, in the case of the compressors according to the prior art, gas is led into the crankcase from the high-pressure side of the compressor. The pressure increase causes the swash plate tilt angle to increase.

In order to be able to regulate the compressor in this way, there must be a minimum tilt angle of approx. 0.5 ° (can vary, depending on the design implementation of various parameters). The minimum tilt angle ensures a minimum piston stroke, which is sufficient to maintain the pressure on the high pressure side. Leaks e.g. this is counteracted by the low pressure side of the system via the expansion element.

In general, it is the following moments that influence the tilting of the swashplate at the center of the tilting movement of the swashplate. In brackets the direction of the moment is given, where (-) means regulating (in the direction of the minimum stroke) and (+) means (regulating in the direction of the maximum stroke).

- moment due to gas forces in the cylinder chambers (+)

- moment due to gas forces from the engine room (-)

- moment due to a return spring (-)

- (moment due to a spring (+))

- moment due to rotating masses (-)

(including moment due to center of gravity; can be (+))

- moment due to translatory masses (+)

Furthermore, the focus of the analysis is on the magnitude of the moment due to the rotating masses (-) (including the moment due to the center of gravity; can be (+ or (-)), based on the moment due to the translationally moved masses (+).

What is useful for the range of very small tilt angles in relation to the aforementioned DE 195 14 748 C2 is extremely disadvantageous in the range of medium and large tilt angles. In this context, EP 0 809 027 may be mentioned. Their subject is a special embodiment of the coupling mechanism between the shaft and the swash plate device. It is pointed out that such a coupling mechanism is of particular interest for high-pressure applications.

This publication also discloses a further feature (particularly relevant as prior art) that is generally important for "modern" air conditioning compressors. Accordingly, it is particularly interesting to provide constant regulation of the delivery rate. It is proposed that the kinematics of the compressor be designed in such a way that the regulating tilting moments acting on the swash plate clearly dominate over the regulating tilting moments. This is particularly noteworthy because these are measures that are fundamentally contrary to the technical teaching described above.

It goes without saying that the term "delivery rate" is relatively vague. The delivery rate would be considered constant if, for example, doubling the speed of the tilt angle of the swash plate device halved. This means that the flow rate would be constant geometrically. Of course, other parameters also have an effect on the delivery rate if, for example, the tilt angle changes, for example a slightly changed delivery rate or oil spill or the like.

The resetting tilting moment of the swashplate device is used for constant control of the delivery rate with changing rotational speeds, since - as already explained - the swashplate counteracts its inclined position due to the dynamic forces on the rotating disc part.

As has been shown above, compressors are known in the prior art, in which the stroke volume tends to increase solely due to the acting moments of upward and downward inertial forces. This may have to be compensated for by appropriate control intervention by the control valves used. With new developments (especially known for CO ₂ ) one tries to reverse this behavior. The necessary control intervention can then be reduced or unnecessary.

For a better understanding, the described tilting behavior as a result of the fluctuation in the number of revolutions is indicated in FIG. 1. It should be borne in mind that this is only an example of the version used and, of course, there may be quantitative differences depending on the version selected. In terms of quality, the selected version is representative of the series compressors used today.

Fig. 1 shows the dependence of the engine room pressure difference, based on the suction pressure over the tilt angle of the swash plate. The following was calculated as an example for the pressures: high pressure 120 bar and suction pressure 35 bar. The speeds were also calculated: 600 rpm, 1200 rpm, 2500 rpm, 5000 rpm, 8000 rpm and 11,000 rpm. However, only 5 of the 6 calculated courses can be seen. This is because the curves for the calculated speeds 600 rpm and 1200 rpm are almost identical to one another. The diagram clearly shows that there are courses that cause the swash plate to be adjusted to larger tilt angles here when the speed increases. In addition to the diagram in the system, the sizes are given that were used for the calculation. For the sake of simplicity, a swashplate was used, which is geometrically essentially described by an inner diameter, an outer diameter and a height. In addition, the piston mass (assumption here: m _κ = 45 g), the pitch circle diameter (assumption here: R = 29 mm) on which the pistons lie, and the number of pistons (assumption here: n = 7 pieces) are relevant.

The derivation of the so-called deviation moment is given below, which is decisive for the tilting of the swivel plate or a swivel ring, and in the case shown is solely responsible for the tilting of the swivel plate or swivel ring, provided that the center of gravity of the Swivel plate or the swivel ring lies both in the tipping point and in the geometric center of the swivel plate or the swivel ring. This is an ideal design case to be aimed for. The following applies in general to the derivation of the moment of deviation

J _yz = -JιCθsα ₂ cosα ₃ - J ₂ cosß ₂ cosß ₃ -J ₃ cosγ ₂ cosγ ₃ oci = 0 ßi = 90 ° directional angle of the x-axis γi = 90 ° with respect to the main axes of inertia ξ'η 'ζ

α ₂ = 90 \ o ^c ß ₂ = ψ directional angle of the y-axis with respect to γ ₂ = 90 ° + ψ main axes of inertia ξ'η 'ζ ₃ = 90 ° ß ₃ = 90 ° -ψ directional angle of the z-axis with respect to γ ₃ = ψ main axes of inertia ξ'η 'ζ

J ₂ = J _η = (r _a * + r, * + ^) 4 J

J ₃ = J _ζ = (r. * + R, *) (Note: J ₃ «2 J ₂

Goal: J _yz should have a certain size

J _y zr J ₃ t J ₂ inevitably increases!)

of inertia

Jyz ⁼ "J2 cosψ sinψ + J ₃ cosψ sinψ

Regardless of Fig. 13:

Moment due to the inertial force of the pistons ßι = θ + 2π (i-1) - n

Zi = R 'ω ² tanα cosßj

M (F _mi ) = m _k 'R' cosßi 'Α

Moment Msw due to the moment of deviation

M _sw = Jyz "ω ²

, _r msw. ,,, _λ msw. , _{_,,,} H ^2. _Λ

JyF = {-— (r _a ² + n ² ) - - - (r _a ² + n ² + -)} cosα sinα

Msw> M _k, _ges and msw

[ω ² R ² 'm _k tanα ^ cos ² ß = ω ² sin2α (3r _a ² + 3n ² -h ² )] 1 = 1 24

The sizes used above mean what follows: θ angle of rotation of the shaft (whereby the above and following considerations are made for θ = 0 for the sake of simplicity) η number of pistons

R Distance between the piston axis and the shaft axis ω Shaft speed α Tilt angle of the swivel ring / swivel plate mk Mass of a piston including sliding blocks or pair of sliding blocks mk, total mass of all pistons including sliding blocks msw Mass of the swivel ring ra Outside radius of the swivel ring ri Inner radius of the swivel ring h Height of the swivel ring g Density of the tilt ring

V volume of the swivel ring ßi angular position of the piston i zi acceleration of the piston i

Fmi mass force of the piston i (including a pair of sliding blocks)

M (Fmi) moment due to the mass force of the piston i

Mk, total moment due to the mass force of all pistons Msw moment due to the set-up moment of the swivel ring / swivel plate due to the deviation torque (J _yz )

J = f (g, r, h) moment of inertia

Finally, it should also be pointed out that in the calculation of the moments of inertia, in particular the deviation moment, a so-called Steiner fraction (y _s ^■ z _s ^■ m) should preferably be taken into account, taking into account the deviation moment as follows:

JYZ = JΫ _Z + Ys' z _s ^• m

For small tilt angles of the swivel _plate , eg a swivel _ring , the proportion J _{γz is} smaller than the _Steiner proportion y _s ^• z _s ^■ m. The part J _γz regulates the compressor mer, while the component y _s • z _s • m always adjusts (set by the position in quadrant Q2, Q4 according to FIG. 12).

It follows from the above considerations that the moment of deviation has two opposing influence components, i.e. both a regulatory and a regulatory component.

The corresponding proportions become effective after a limit tilt angle α _{G is} exceeded, where α <α _G applies:

y _s • z _s ^■ m> Jyz "(regulating), and for α> α _G vice versa (ie regulating).

1 contains a further diagram which represents the moment due to the rotating masses (-) (including the moment due to the center of gravity; here = 0), the moment due to the translationally moved masses of the pistons and sliding blocks (+) , as well as the sum of both. It can be seen from the sum that this is positive for all tipping angles and that the engine "regulates" for all tipping angles solely on the basis of the inertial forces and the inertia of the swash plate. The diagram shows the moments for an average speed of 2500 rpm. The effect of course becomes smaller at lower speeds, and consequently larger at higher speeds.

2 shows the calculation scheme and the diagram corresponding to FIG. 1 for an almost identical engine. However, the amount of

Swashplate increased from 10 mm to 18 mm. The consequence of this is that the relevant moment of inertia J _z increases to twice the value.

A regulating behavior of the swashplate engine can be seen in a first diagram of the figure. This trend is indicated by the inserted arrow, with "n" denoting the speed (cf. the trend with FIG. 1!). Another (smaller) diagram also contains the torque curves with regard to the torque due to the rotating masses (-) (including the torque due to Center of gravity; here = 0), the moment due to the translationally moving masses of the pistons and sliding blocks (+), and the sum of both. For the sum it can be seen that this is negative for all tilt angles and that the engine "regulates" for all tilt angles solely on the basis of the inertial forces and the inertia of the swash plate. The diagram shows the moments for an average speed of 2500 rpm.

On the basis of the literature references cited, the two courses mentioned "regulating" and "regulating" can be regarded as state of the art. The "regulating" behavior of current series compressors can often be determined. With new developments one tries to change this trend into the opposite.

In addition to the two cases explained - overcompensation of the inertial forces of the pistons by the inertial forces of the

Swashplate as well

- Undercompensation of the inertial forces of the pistons by the inertial forces of the

Swashplate, it is also conceivable to provide compensation.

From the mathematical context it can be seen that the

Equation of speed influence can be shortened (Fig. 2). Otherwise, there are also geometric variables that are related to each other and can, in principle, including component densities and density distributions, be selected so that the sum of the moments due to inertial forces can be set to zero.

However, an influence of the tilt angle cannot be avoided. This results from the courses of the terms tan (α) and sin (2α). The curves of the angular functions are shown in the diagram in FIG. 3. It can easily be derived from the diagram that the influence is very small with a small tilt angle, but is considerable with a larger tilt angle. As a rule, the swash plate tilt angles of the compressors are determined by a minimum value and a maximum value Limited value. For example, values between a tilt angle of approximately 0 ° and a maximum of approximately 25 ° are conceivable. In practice, the values are between 1 ° and approx. 18 °. Building on this, it can be seen from the diagram that a deviation of about 13% can be expected in the last-mentioned area. In other words, if a constructive balance between the regulating and regulating masses has been achieved for the minimum tilt angle, one must nevertheless expect undesirable tilt behavior (speed influence due to the tilt angle) in the opposite limit of the swash plate.

In order to achieve the greatest possible compensation of the mass forces, it makes sense to provide the compensation for a maximum tilt angle or a theoretical (virtual) tilt angle (e.g. o = 24 ° (> = α _max = 16 °)) that is greater than the maximum Tilt angle is. This results from the knowledge that with a small tilt angle the difference between tan (o) and sin (2o) is small anyway.

The diagram of FIG. 4 contains the result of the calculations for a design for the tilt angle 16 °, which is to be taken as an example for this engine as the maximum tilt angle. The height of the swash plate was adjusted to 14.292 mm, the moment balance also shows balanced conditions again. It should be mentioned again that other swashplate parameters can of course also be used for setting the moment of inertia. In order to make it easy to compare, the swash plate height parameter was only selected as an example.

The control behavior of the swash plate according to the diagram in FIG. 5 shows the desired result. In the entire working range of the swashplate (from the minimum to the maximum tilt angle) there is no significant uplifting effect due to moments of moving masses, a wide spread of the characteristic curves is avoided by the fact that there is an intersection at the maximum tilt angle.

A very good compensation arises in the range of small tilt angles because of the small effect (difference) of tan (α) and siπ (2o) as well as for the maximum Tilt angle of 16 ° for which the mass forces have been compensated for by selecting the parameters. At medium tilt angles, the curves "drift" slightly apart.

The following interpretations are conceivable for the case of compensation of the mass forces: for α = α _max Mκ, _ges = Msw

6 shows various control characteristic curves for operating pressures (suction pressure / compression pressure; n = 5000 rpm) and the bases for the calculation. The higher the compression pressure at which the compressor is operated, the greater the pressure to be regulated in the engine room. The lower the intake pressure, the lower the pressure to be regulated in the engine room. The slope of the control characteristics is essentially determined by the spring force that acts on the swashplate mechanism.

As in all of the previously mentioned diagrams, the characteristic curves were calculated with a spring constant with respect to the return spring (return in the direction of the minimum stroke) of 60 N / mm. If the spring constant were chosen to be smaller, the curves would be less sloping in the direction of larger tilt angles. If the spring constant were chosen to be larger, the curves would decrease more sharply in the direction of larger tilt angles.

Each curve for 5000 rpm can be seen as representative of a curve bundle of a certain operating point. If it is taken into account that a certain control pressure of at least 2-3 bar above the suction pressure is required and that favorable control behavior is achieved by the fact that the characteristic curves have a certain slope that is as linear as possible over a wide range, then it is plausible that a "bundle of curves" lying close together "Rather for all operating areas lies in the desired area of the map than control curves that" drift apart "more. In the case of such negative cases, for example in the case of a regulating behavior according to FIG. 1, it is clear that parts of control curves are very simply in the range below the level of 2-3 bar above the suction pressure. To avoid this, a softer return spring would have to be used. In particular at high speeds, however, it can happen that an increasing characteristic arises compared to the falling characteristic at low speeds. Experience shows that very undesirable control effects occur in such cases. In particular, individual pressures can no longer be assigned a defined tilt angle (occurrence of relative maxima or minima or no or too little slope or turning points).

It is an object of the invention to provide an improved axial piston compressor of the generic type, which is characterized in particular by practical control dynamics.

This object is achieved by an axial piston compressor with the features of claim 1. Appropriate developments of the inventive concept are the subject of the dependent claims.

It is an essential idea of the invention to provide a swash plate device in which the moments due to the inertial forces are so effective in magnitude and direction that in the range of low tilt angles an "adjustment" (swash plate increases its tilt angle, thus increasing the delivery capacity) of the compressor solely due to the moments due to the inertial forces, and in the range of medium to large tilt angles there is an "Abregein" (swashplate reduces its tilt angle, thus reducing the delivery capacity) solely due to the moments due to the inertial forces.

The essential measure is that the deviation moment of the swash plate is structurally specified in such a way that it causes the swash plate to be "adjusted" in the area of small tilt angles together with the pistons or separately. For this purpose, a moment M _S w must be present in this area due to the deviation moment> 0, and exactly one must exist in the area of the minimum tilt angle Give tilt angle in which the moment M _S w = 0 due to the deviation moment. If the tilt angle increases further, the deviation torque increases again and has a regulating effect. The slope of the moment M _{k, ges} due to the mass forces of the pistons must be smaller than the slope of the moment due to the moment of deviation.

By dimensioning the swash plate with the aim of producing such behavior, there is the possibility of accelerating, strengthening or improving the "straightening" of the swash plate in the area of small tilt angles and in the area of larger tilt angles by means of the "regulating" behavior restrict the necessary control activities (control valve (s) switches bypasses to vary the engine room pressure) to what is necessary and thus make the compressor operation more energy efficient. Furthermore, there is a more favorable dynamic behavior, especially reduced swinging and "counter rules" by the valves.

Advantages and expediencies of the invention result from the dependent claims and the description with reference to the accompanying figures. Of these show:

1 to 5 graphical representations and tables of values and calculation instructions for the design of the swash plate arrangements of axial piston compressors with regard to their tilting behavior,

6 and 7 are a perspective view and side views of the components of an axial piston compressor and essential to the invention

8 to 12 graphical representations or value tables for the representation of the moments occurring under defined structural boundary conditions.

6 and 7, a swashplate mechanism is given, by means of which the design (the subject matter of the invention) can be implemented constructively, wherein 7 shows a perspective exploded view and FIG. 8 shows two side views of the essential components at a minimum or maximum tilt angle.

The swivel ring mechanism 100 shown comprises an annular swivel plate, i.e. a swivel ring, 101, which is mounted on a drive shaft 104 via a guide or sliding sleeve 102 and a compression spring 103 located therein, which is adjustable in inclination. The swivel ring 101 is rotatably driven by the drive shaft 104 and is articulated by a special design of the guide sleeve 102 about a swivel axis running transversely to the drive shaft. This pivot axis is defined by two bearing bolts 104a, 104b, which are rotatably received in bearing sleeves 105a, 105b of the guide sleeve 102 and correspondingly arranged radial bores 106a, 106b of the swivel ring 101. The bearing sleeves 105a, 105b are dimensioned such that they bridge an annular space formed between the guide sleeve 102 and the swivel ring 101.

Furthermore, the swivel ring 101 is connected in an articulated manner to a support element 107 rotating together with the drive shaft 104, this connection being designed as an axial support. It takes place through a support arch 108 which is operatively connected to the swivel ring 101. This support arch 108 is designed such that it engages over a joint arrangement which is effective between a piston 109 of the arrangement and the swivel ring, in such a way that regardless of the inclination (the tilt angle) of the Swing ring 101 any collision between this and the support arch 108 on the one hand and a piston foot 110 comprising a joint arrangement on the other hand is excluded. The support element 107 is part of a disk 111 connected in a rotationally fixed manner to the drive shaft 104.

A support surface of the support arch 108 extends approximately concentrically to the center of an articulation arrangement that is effective between the piston 109 and the swivel ring 101. The axial support is therefore effective outside the joint arrangement mentioned, with the result that it is not impaired by axial support measures. The connection between the swivel ring 101 and the support arch 108 is established by two connecting bolts 112a, 112b, which are in a pair of bores 113a, 113b of the swivel ring offset by 90 ° with respect to the aforementioned bores 106a, 106b and in correspondingly arranged bores 114a, 114b of the Intervene in the support arch yourself. The articulation arrangement with respect to the piston foot 110 of the piston 109 is formed, in accordance with the prior art, by two spherical segment-shaped articulated blocks 115a, 115b, the spherical surfaces of which, on the one hand, in a correspondingly shaped lower end face of the piston 109 and a corresponding surface of an opposite extension 117 of the Piston foot 110 are on the other hand. A space 116 is formed between the hinge blocks, into which the swivel ring 101 engages in such a way that opposite end surface sections touch the flat surfaces of the hinge blocks.

It can be seen that the pivot bearing of the

Swivel ring 101 is used only for torque transmission and the support element 108 only for the axial support of the piston 109 or for gas force support. The torque transmission is therefore decoupled from the axial support of the swivel ring 101.

The support surface for the support arch 108 on the support element 107 is also of particular interest. This is designed as a section 118 of a cylinder surface. By shifting the support line when the inclination of the swivel ring 101 changes, i.e. to avoid a displacement from the "center" of the piston 109, the support arch 108 is mounted so that it can move in the radial direction relative to the swivel ring 101.

In the left image in FIG. 7, four areas are designated Q1, Q2, Q3 and Q4. In the previous examples it was assumed that the center of gravity of the swash plate is on the tilt axis, which is defined perpendicular to the shaft center axis. Building on this, however, compressors according to the prior art often have focal points in the area of the swash plate, in which the focus of the swash plate is not on the tilt axis. In a preferred embodiment these points coincide. An "offset" is planned in another. The focal points in the quadrants Q have the following effects: Q1 (positive coordinates z and y): regulating Q3 (negative coordinates z and y): regulating Q2 (positive coordinates z and negative y): regulating Q4 (negative coordinates z and positive) y): uplifting

If no additional mass balancing is provided, the focus of many swash plates corresponding to the state of the art is in the area Q4.

It is of course possible that a center of gravity arranged in any quadrant changes the shaft side with respect to the shaft axis when the swashplate is tilted and e.g. converts regulatory behavior into regulatory management. However, it has been recognized that in the area of the shaft axis the centrifugal force and any resulting tilting moment are of course kept within limits, i.e. the center of gravity will only be particularly relevant if there is a certain distance from the shaft center axis.

In connection with the invention, the following two focal positions are important (offset which has an uplifting effect): Q2 (positive coordinates z and negative y): uplifting Q4 (negative coordinates z and positive y): uplifting

For better understanding, the same parameters (swashplate geometry) were used as in FIGS. 1 and 2.

In the diagram on the left, at the top of FIG. 8, this is the case la:

"Regulating engine" with center of gravity 0. In the diagram at the bottom left of FIG. 8, case 2a is:

- "regulating engine" with center of gravity 0, shown. The only difference between the two calculations is the height of the swash plate (see Appendix 6 h = 10 mm and Appendix 7 h = 18 mm). A total of 4 speeds were calculated. The diagram on the right, above represents case lb: - "Regulating engine" with focus in Q4. In contrast, in the diagram "right, below", case 2b:

- "up- or down-regulating engine" represented by the center of gravity in Q4. Cases la, lb, 2a can be regarded as known; Sources and examples have been explained above. Case 2b is related to the invention.

In FIG. 8, only the resulting moment, ie (M _κ , g _es + M _S w), is shown as a result of the mass forces, which decides the criterion of "excitement" or "regulation". FIG. 9 shows the value tables which form the basis for the diagrams in FIG. 8. In FIG. 10, cases 1b and 2b are shown in more detail in addition to FIG. 8. The diagrams on the right, above and on the right, below correspond to those in FIG. 9. The individual moments are shown in the diagrams next to them, specifically for a selected speed of n = 6000 rpm.

The picture on the right below has special reference to the invention. The moment due to the inertial forces of the pistons at a tilting angle of 0 ° of the swash plate = 0. The moment due to the moment of deviation (M _sw ) of the swash plate is> 0 and causes a positive (regulating moment). Due to the deviation moment of> 0, the resulting moment (Msw + Mκ, _ges ) is the same in magnitude and direction.

Starting from a tilting angle of 0 °, the tilting moment M _κ , _{total increases} because the piston path becomes larger as the mass forces of the pistons become larger. On the other hand, the tilting moment strives towards its zero position (deviation moment = 0 °), which is approximately at a tilting angle of 0.6 °, corresponding to the moment due to the deviation moment, due to the swash plate (M _S w). If the angle of tilt increases further, the moment of deviation of the swash plate no longer has an upward-looking, but rather a regulating effect. Nevertheless, the effect of the swash plate in the range of 0.6 ° to 2 ° is not sufficient to ensure a total "momentum" in the sum of moments (M _κ , g _e s + M _Ξ w). As a result, the sum of the moments (M _κ , _ges + Msw) is positive up to about 2 ° and has an uplifting effect. Since the gradient of the moment due to the swash plate is greater in magnitude than the gradient of the moment due to the pistons, the trend reversal is achieved at 2 °: - The moments due to the inertial forces of the engine have a regulating effect of up to approx. 2 °.

- From approx. 2 °, the moments have a regulating effect due to the inertial forces of the engine.

It is obvious that a slight change in the center of gravity of the swash plate allows the intersection of the course of the resulting moment with the x-axis to be shifted almost arbitrarily in the diagram. The center of gravity is taken into account by the tax portion within the moment of variation. In principle, even with a center of gravity (0/0), i.e. without a tax component of the moment of deviation, it can be provided in a constructive manner that the moment of deviation in the area e.g. <0.6 ° has its "zero position".

Furthermore, the invention aims first of all at the conventional tilt angle range between a minimum and a maximum tilt angle and in a further step at minimizing the minimum tilt angle in the direction of 0 °.

The diagrams in FIGS. 8 and 10 and the value tables in FIG. 9 show that, of course, at low compressor speeds (e.g. 800 ... 3000 rpm) the moments are extraordinarily small, especially in the range of small tilt angles. The question arises of how you can get things up with such small moments.

From the table of values (Fig. 9) on the right, below, a torque of 0.04 Nm can be estimated for a usual minimum tilt angle of, for example, 0.9 ° and a compressor speed of 1500 rpm by linear interpolation. Even such a small moment can shift the swashplate against the spring force by a few l / 10mm, which corresponds to a few 1/10 ° change in tilt angle. It should be taken into account that the possibility of a tilt angle reduction already in the range of 0.9 ° For example, 0.7 ° can be energetically very important for the application "clutchless operation" of the compressor.

11 and 12 show the control curves for the cases already described. The spring constants selected differently for the "regulating" case and the "regulating" case must be taken into account. The choice of different spring constants is necessary in order to set a meaningful slope of the characteristic curves, which is necessary for regulation. Characteristic of the control characteristics in the diagram according to the subject of the invention is also the intersection at about 2 °, which shows the "trend reversal" of the resulting moment.

The embodiment of the invention is not limited to the example described above and the emphasized design focal points, but is also possible in a large number of modifications which are within the scope of professional action. There is scope for the designer, in particular with regard to the concrete dimensions of the swivel disk and its center of gravity, provided that the criteria formulated in the appended claims are taken into account.

Claims

1. Axial piston compressor, in particular compressor for the air conditioning system of a motor vehicle, with a housing and a compressor unit arranged in the housing and driven via a drive shaft (104) for the suction and compression of a refrigerant, the compressor unit running axially back and forth in a cylinder block Piston (109) and a swash plate driving the pistons, rotating with the drive shaft (104), as a swash plate or swash plate or swivel ring (101), so that the swivel plate can be determined by defining the geometry and / or the mass and / or the center of gravity is constructed and dimensioned such that its moment M _s as a result of the deviation moment I _yz , where M _S w = I _yz * ω ² , ie the moment as a result of the inertia and the center of mass of the swashplate, together with the moment M _k , _tot due to the translationally moving masses, in particular the pistons, possibly including sliding teine (115a, 115b) piston rods or the like, in the area of small tilting angle with increasing speed and constant pressure difference Δp between high and low pressure side an increase in the tilting angle and thereby an increase in the delivery rate and after exceeding a limit tilting angle o _limit , which applies M _S w = M _k , _tot , when the speed is increased and the pressure difference remains constant, the tilt angle is reduced and the delivery rate is reduced.

2. axial piston compressor according to claim 1, dadu rc hge ke nn ze ichn et that the swash plate (101) is constructed and dimensioned such that the course of the moment M _sw due to the deviation moment I _yz as a function of the tilt angle o at the same speed essentially has a larger gradient than the course of the moment M _{k / ges} due to the translational moving masses depending on the tilt angle.

3. axial piston compressor according to claim 1 or 2, dadu rch ge ke nn ze ichn et that the sum of the moment M, _ges due to the translationally moved masses and the moment Msw due to the deviation moment I _y2 in the tilt angle range between a predetermined minimum tilt angle o _m i _n and a maximum tilt angle α _max, the sign, in particular from "plus" to "minus", changes, which means a transition from an increase in the tilt angle and a consequent increase in the delivery rate to a decrease in the tilt angle and thereby the delivery rate.

4. Axial piston compressor according to one of the preceding claims, so that a tipping point of the swivel plate (101) is defined as the point of intersection of the axes of rotation of the drive shaft (104) and the swivel plate.

5. Axial piston compressor according to one of the preceding claims, so that the center of gravity is divided into four quadrants (Q1, Q2, Q3, Q4) when dividing the space comprising the drive shaft (104) and swivel plate (101) the swivel plate either in a first, front quadrant (Ql) delimited by the drive shaft and the piston support facing the piston facing the piston, or in a second, front, on the side opposite the first quadrant (Ql) relative to the drive shaft lying quadrant (Q2), or in a third, rear, relative to the swivel plate at the level of the second quadrant (Q2) behind, ie on the side facing away from the piston, the swivel plate arranged quadrant (Q3), or in a fourth, rear, relative to The swivel plate is installed at the level of the first quadrant (Q1) behind, ie on the side facing away from the piston, the quadrant (Q4) arranged.

6. Axial piston compressor according to one of the preceding claims, so that swivel plate (101) on the one hand and piston (109), optionally including sliding blocks (115a, 115b), piston rods or the like, on the other hand, are constructed and dimensioned in this way, that at a tilt angle o of essentially 0 °, the moment M _S w due to the deviation moment I _{yz of} the swivel plate is greater than zero and the moment M _k , _ges due to the translationally moving masses is essentially zero, such that a positive Total moment causes the tilt angle α of the swivel plate to increase, while above a predetermined tilt angle in the range between 1.5 ° and 2.5 °, in particular at approximately 2 °, the slope of the moment M _{k; ges} due to the masses moved in translation, the slope of the moment M _S w due to the moment of deviation I _yz than offset such that starting from this value, a reduction of the tilt angle of the tilt plate is effected.

7. Axial piston compressor according to one of the preceding claims, dadu rc hge ke nnzeichn et that the swash plate (101) is constructed and dimensioned such that its moment M _s due to the deviation moment I _yz at a tilt angle α in the range between 0.4 ° and 0.8 °, in particular at approximately 0.6 °, is zero.

8. axial piston compressor according to claim 6 or 7, dadu rc hge ke nn ze ichn et that the tilt angle value, from which the total moment from the moment _k , _it the translationally moving masses and the moment M _S w as a result of the devia - tion torque I _{yz of} the swashplate causes a reduction in the tilt angle, and / or the tilt angle value at which the torque M _S w is zero due to the deviation torque I _yz is set by suitable predetermination of the center of gravity of the swashplate (107).