EP1778977A1

EP1778977A1 - Axial piston compressor

Info

Publication number: EP1778977A1
Application number: EP05771046A
Authority: EP
Inventors: Otfried Schwarzkopf
Original assignee: Valeo Compressor Europe GmbH
Current assignee: Valeo Compressor Europe GmbH
Priority date: 2004-08-18
Filing date: 2005-08-05
Publication date: 2007-05-02
Also published as: US20090104048A1; DE102004040042A1; WO2006018162A1

Abstract

An axial piston compressor, particularly a compressor for the air-conditioning system of a motor vehicle, comprising a housing and a compressor unit which is arranged inside the housing and driven by a drive shaft and used to suction and compress a cooling agent, wherein the compressor unit comprises pistons which move axially back and forth in a cylinder block and a pivoting plate (a slanting plate, a swash-plate or a pivoting ring). The pivoting plate is configured or mounted in such a way that the tipping behaviour thereof acts in an automatically limiting manner and such that when the speed of the compressor is high, particularly very high indeed or when it reaches a maximum, the maximal pivoting plate deflection angle amax is smaller than the maximum deflection angle at low compressor speeds.

Description

"Axial piston"

Description

The invention relates to an axial piston compressor, in particular a compressor for the air conditioning system of a motor vehicle according to the preamble of claim 1.

In DE 195 14 748 C2, the effective on a swash plate basically all existing in the prior art compressors, as well as in the series einge¬ led compressors, effective tilting moments are explained, which contribute significantly to Kippver¬ hold the swash plate. The influencing variables, which act as moments about the tilting center of a swivel disk, are in detail the following moments, wherein the direction of the moments is indicated in brackets and (-) regulating (in the direction of a minimum lift) and (+) controlling ( in the direction of the maximum stroke):

Moment due to the gas forces in the cylinder chambers (+) - moment due to the gas forces from the engine compartment (-)

Torque as a result of a return spring (-) (minimum stroke direction) Moment due to a set-up spring (+) (maximum stroke direction) Moment due to rotating masses (-); including moment due to center of gravity (eg swashplate: tilting position ≠ center of gravity): can be (+) or (-)

Moment due to translationally moving masses (+) In this case, the momentum (referred to in the expanded text as M _sw ) usually acts as a result of the rotating masses; Only in the area of very small tilt angles can an adjusting moment be generated, for example, by an exposed center of gravity position (Steiner component in the calculation of the moment of deviation J _yz ) in the swash plate (see DE 195 14 748 C2). Even in the area of small tilt angles, the proportion of the deviation moment J without stone fraction prevails, and the swashplate has an increasingly declining tilting moment as the tilt angle increases.

With regard to DE 195 14 748 C2 a course for the translationally moving masses is further indicated, which, as already explained, aufregelnd effective.

Of interest is then still the sum of the momentum, which is also shown graphically (Fig. 4 of DE 195 14 748 C2). For the entire tilt angle range, the engine has a aufregelndes behavior, since the translationally moving masses dominate the control behavior in each area.

Another engine is known from EP 0 809 027 A1, which is characterized in that the delivery rate of the compressor is compensated by the dynamic behavior of the engine of the compressor, so that the delivery rate can be kept constant. Specifically, it says there as follows: "For a constant control of the flow rate at varying rotational speeds, the restoring torque of the Tau¬ melscheibe can be exploited, which counteracts their inclination due to dynamic forces on the co-rotating disc part."

Building on EP 0 809 027 A1, DE 198 39 914 A1 discloses measures for how such a control behavior (at least partial compensation of the delivery rate) can be achieved. It is proposed to dimension the component mass of the swiveling disk with respect to the translationally moved masses in such a way that the centrifugal forces of the swivel disk influence the control behavior of the same. Specifically, this means that the rotating mass of the drive pulley is greater than the common mass of all pistons, so that the centrifugal forces occurring during rotation of the drive pulley are sufficient to deliberately counteract the pivoting movement of the drive pulley. act, and thus the. Piston stroke and thus to influence the flow rate, in particular to reduce or limit.

DE 103 24 393, which is based on the applicant and has not yet been published, explains why the component mass should not be the preferred parameter in order to influence the control behavior of the engine as a result of speed fluctuations as desired.

The desired control behavior of the compressor is primarily not achieved with the component mass of the swashplate in relation to the translationally moved masses, but taking into account the mass moment of inertia of the unit "swash plate", which depends more on its geometry than on the component mass Speed variations or speed changes to compensate for the moment due to translationally moving masses directly by the moment due to rotating masses, or even overcompensate.

In such compressors, it is desirable to reduce the frequency and intensity of Regel¬ interventions to a low level. With respect to the prior art and DE 195 14 748 C2, it is extremely disadvantageous that an increase in the delivery volume as a result of an increase in the rotational speed as a result of an increase in the delivery volume due to an increase in the delivery volume due to an increased Schwenkscheibenkippwinkels added.

This effect must be compensated by appropriate control interventions. This is not comfortable, expensive and reduces the efficiency (fuel consumption).

With the EP 0 809 027 A1 the goal is given, which is to be reached: Constant regulation of the flow rate.

However, it can be very easily demonstrated that this is not possible solely by the installation torque acting on the swivel disk (de-excitation).

The delivery volume is directly proportional to the speed, ie doubles the speed, so doubles the volume. In contrast, for the tilting moment of the swash plate, which is triggered by the relevant moment of deviation, the following equation applies:

M _sw = J _yz ω ²

Since the rotational speed quadratically influences the overturning moment, the stated goal "constant regulation of the flow rate" can not be represented solely by the construction or dimensioning of the swivel disk.

The object of the invention is to admit a compressor with optimized control behavior in which a full load state is avoided at high and highest compressor speeds.

This object is achieved by a compressor with the features according to claim 1, wherein preferred developments and embodiments are described in the subclaims.

An essential aspect of the invention is therefore that the tilting behavior of the swash plate is so automatically limiting effect that at high speeds of the compressor, especially at very high speeds or the maximum speed of the compressor, the angle of maximum deflection of the swash plate is smaller than that Angle of maximum deflection α _max at low speeds of the compressor. By such a measure is excluded that the compressor operates at high speeds, in particular at its maximum speed, with an excessive delivery volume. Since this measure engages regulating in the delivery volume, the number of required control operations is reduced (usually swash plate compressors are controlled by a pressure difference between a prevailing in the engine room of the compressor pressure and a pressure prevailing at the compressor outlet side pressure, this pressure difference the piston stroke and thus the delivery volume of the compressor determines). This also leads to a significantly reduced number of performance-consuming control interventions or, if necessary, no control intervention being necessary, especially in the region of high rotational speeds, especially in the case of increased engine speed Use of a compressor in motor vehicles in these moments, the power unge¬ diminished the drive of the motor vehicle to send. This is very advantageous especially in overtaking.

Preferably, a compressor according to the invention is designed such that both the geometry and the dimensioning of all translationally moving parts of the compressor and all rotationally moving parts are such that for predetermined tilt angle of the swash plate, in particular between a predetermined minimum tilt angle and a predetermined maximum tilt angle the moment M _k _ _ges as a result of the translationally moving masses is chosen to be smaller than the moment M _sw due to the Deviationsmoments, ie is chosen smaller than the torque due to the Mas¬ inertia of the swash plate, that at high speeds of the compressor, especially at very high speeds or a maximum speed, the angle of maximum Aus¬ steering of the swash plate is smaller than the angle of maximum deflection at smaller ren speeds of the compressor. To the translationally moving parts of the compressor include the piston, possibly also the piston rods and sliding blocks or the like. The rotationally moving parts are essentially the swash plate, and possibly one or more drivers to count. In this embodiment, it is an embodiment of a compressor according to the invention that is structurally simple to implement and thus inexpensive to produce. In addition, of course, the advantages already explained above, in particular the advantage of a small number of control actions, which become necessary during operation of a compressor according to the invention, are fully valid for the prevailing preferred embodiment.

It should be noted at this point that modern axial piston compressors, in particular compressors, which are intended for use in a motor vehicle air conditioning system, bring at partial load such a large refrigerant mass flow, which virtually corresponds to a power of the compressor, in order to obtain sufficient power to provide high cooling capacity. The Ver¬ denser must therefore be regulated at high, very high and even at the highest speed, with the present invention, the number of Re¬ geleingriffe required is greatly reduced or no regulatory intervention are more necessary. Furthermore, reference is also made to the safety aspect, which plays a significant role in particular in compressors that are operated with a high-pressure refrigerant. By the construction according to the invention prevents a high speed and a large piston stroke of the compressor from occurring simultaneously, which in the case of compressors according to the prior art can definitely lead to the compressor pressure rising in the event of (possibly sudden) occurrence of high speed and long stroke in that the compressor housing bursts.

He inventive compressor according to may comprise at least one device which exerts a force on the swash plate. Said device is preferably assigned to the same in addition to a device for adjusting or for controlling the engine room pressure of the compressor. This device or these devices may or may act alone as the automatically limiting member of the swash plate, but it may also be arranged in a compressor, in which already the mass distributions or the torque distribution of the swash plate Abregein same at high speeds causes. In this case, an already existing due to the geometry of the swashplate mechanism tendency of the compressor to be depressed at high speed, supported or amplified. The at least one device for exerting the actuating force optionally comprises an elastic element, which may be present in particular in the form of a return spring, and / or an actuator or an actuating piston. Alternatively or additionally, a compressor according to the invention may comprise a centrifugal force-dependent actuator and / or a further spring. It is also conceivable that the at least one device for exercising the actuating force comprises a throttle point, whose cross-section can be varied by means of an actuator, in particular by means of an actuating piston. The throttle point may be arranged in particular on the suction or pressure side of the compressor. If the throttle point is arranged on the suction side of the compressor, the density of the suction gas can thereby be regulated or lowered as desired. As a manipulated variable for the actuator, in particular control piston, a thrust in the engine of the compressor prevailing pressure and / or the prevailing at the outlet side of the compressor pressure is to be preferred. These manipulated variables are easily accessible. In a further preferred embodiment, the actuator is controlled or controlled internally, in particular via a magnetic coil or the like device. Alternatively, a constant cross section of the throttle is conceivable. In all the above imple mentation forms are structurally simple measures, which are thus inexpensive to manufacture. ever According to the application of the compressor and desired force or restoring force, the various measures can be realized either individually or in combination with each other in the compressor, whereby a desired control behavior is easily achievable.

In a preferred embodiment, the center of gravity of the swash plate is on the tilting axis thereof. The tilting axis of the swashplate, in turn, preferably lies on the central axis of the drive shaft. These constructive measures ensure a quiet, low-wear running of the compressor with the least possible imbalance.

In a further preferred embodiment, the swivel disk is annular, i. designed as a swivel ring. This ensures an optimum relationship between the mass of the swash plate (which is low) or the swivel ring and its or their mass moment of inertia (which is high).

Preferably, the angle of maximum deflection of the swash plate in the range of small and medium speeds of the compressor corresponds to an angle oc _max , while the angle of maximum deflection at the maximum speed of the compressor corresponds approximately to an angle of α _max / 2. Areas of low and medium speed extend in the parlance of the present application to about half the maximum speed of the compressor. In compressors of modern design, which reach a maximum speed of about 8000 to 10,000 revolutions per minute, thus extending a range of low and medium speeds up to about 4000 revolutions per minute, it being understood that the above figures selbst¬ of course are to be regarded as exemplary only.

The swash plate of a compressor according to the invention is preferably for speeds from about 4000 to 5000 revolutions per minute no longer up to one or the angle cx _max ver pivoted. As a result, an optimal load limitation is guaranteed, which has advantageous effects especially under the safety aspect. Both a risk of icing and the risk of bursting of the compressor housing is significantly reduced compared to compressors according to the prior art. In a further preferred embodiment, the limitation of the pivot angle for increasing rotational speeds of the compressor becomes stronger. Also for this imple mentation form, the advantages arise, in particular when considering the safety aspect, analogous to the foregoing.

The ratio of the moment of deviation in the y-direction and the total mass of all translatably movable parts J / m _k , to which, as explained above, for example the pistons, possibly also the sliding blocks and piston rods, is preferably at least about 1000 mm ² . Even more advantageous is a ratio J _y / m _{k tot} of more than

1500 mm ² . The ratio of deviation moment in z-direction and total mass of all translationally movable parts J _z / m _k _ _ges is in a further preferred embodiment at least about 2000 mm ² , even more advantageous is a value of more than 3000 mm ² . Due to the large ratio between Deviationsmoment and total mass of the translationally movable parts, the desired control characteristic is achieved in a simple manner.

According to the invention, it has also been recognized that a "suitable" spring constant should be chosen (this determines the slope of the control characteristic.) In a further preferred embodiment, a return spring, which exerts a restoring force on the deflected swivel disk, has a spring constant It is even more advantageous to use return springs having a spring constant of less than 30 N / mm, of course, the moments of the translationally and rotationally moving parts are respectively adapted accordingly springs with such spring constants are available inexpensively, require a small installation space and are also low-wear.

In the embodiments described herein, the swashplate has a minimum and maximum stop defined directly or indirectly (via the sliding sleeve). The maximum stop is not reached at high speeds and is fixed in the embodiments described above, and can not be regulated. In a further preferred embodiment, a compressor according to the invention has a speed-dependent stop, which limits the angle of maximum deflection of the swash plate as a function of the compressor speed. This speed-dependent stop serves as a further measure to ensure that at high speeds, the angle of maximum deflection of the swash plate is lower than pay at low Dreh¬. It is conceivable in this case, for example, a paragraph on the drive shaft, which prevents pivoting beyond a predetermined angle. Also, another construction, for example, has a displaceably mounted on the drive shaft sleeve or the like., Would be conceivable. The control of the stop can for example be done via the (speed-dependent) centrifugal force.

It should be noted at this point that it has been recognized in the context of the invention that the avoidance of exposed center of gravity positions avoids stronger curvatures of the course of the control characteristic.

The invention will be described below with reference to further advantages and features by way of example and with reference to the accompanying drawings. The drawings show in:

Fig. 1 is a sketch of a pivot ring of a compressor according to the invention;

FIG. 2 shows a sketch of a swivel disk for explaining the coordinate system used in the present application; FIG.

Fig. 3-7 diagrams showing the control characteristics of two embodiments of a compressor according to the invention as a function of various parameters such as speed, suction pressure, compression pressure and spring constant a Rückstell¬ feather; and

Fig. 8 is a diagram illustrating the control characteristics of a compressor according to the invention as a function of other (additional) parameters. To better illustrate the invention, the tilting moment of schwenkba¬ ren share the swash plate means can then be expressed in simplified form by equations that are relevant for an annular swash plate component.

The simplified derivation shown below is therefore to be considered as exemplary only; With more complex geometry of the swash plate, the moments of inertia and moments of deviation and other variables influenced by geometry and density would be calculated by means of CAD.

For the derivation of the moment of deviation, the following mathematical relationships generally apply (coordinate system Fig. 1):

J _yz = Ji cos ₂ COSCt ₃ - J ₂ cosß ₂ cosß ₃ - J ₃ cosγ ₂ cosγ ₃

(X ₁ = 0 P ₁ = 90 ° direction angle of the x-axis

Y ₁ = 90 ° with respect to the principal axes of inertia ξ, η, ζ α ₂ = 90 ° β ₂ = ψ Directional angle of the y-axis γ ₂ = 90 ° + ψ with respect to the principal axes of inertia ξ, η, ζ CC ₃ = 90 ° ß ₃ = 90 - ψ Direction angle of the z-axis γ ₃ = ψ with respect to the main axes of inertia ξ, η, ζ

The coordinate system used here is apparent from the illustration in FIG. Furthermore applies to a "ring":

m \ ₂ 2 h I ^{j2 =: Jη =} T ^r "'3 ^S ° ^Wle

(Note: J ₃ «2J ₂ )

Goal: J should have a certain size; J _y2 T> - J ₃ TJ ₂ inevitably increases.

For the moment of deviation, which is decisive for the pivoting movement, the following applies:

I _7Z ⁼ -Ji cosψ sinψ + J ₃ cosψ sinψ

Regardless of Fig. 2, the momentum is due to inertial forces of the piston:

P ₁ = θ + 2π (il) -

Z ₁ = Rω ² tanα cosß, F _mι = m _k z _t M (FJ = m _k R _Ä cosß

and the moment M _sw due to moment of deviation:

M "= J _yz ω ²

cosαsmα

J ^H

J = ^ sin2α (3r> 3r, ^2- F)

In connection with the invention, the following torque ratio should be set constructively:

M, _w > M _{k> ges} or ω ² R ² m _k tan aΣ cos ² ß <ω ² ^^ - sin2a (3 ^ + 3η ² -h ²⁾

/ = 1 ^

As already explained, the (tilt) moment of the swivel ring can be deliberately adjusted by various parameters (geometry, density distribution, mass, center of mass) as a result of the associated deviation moment

M _sw > M.

applies. In particular, however, M _{sw should be} significantly larger than M _k .

In connection with the given equations,

θ rotation angle of the shaft (the preceding and following considerations of the

For simplicity, for θ = 0 are employed) η number of pistons

R Distance of the piston axis to the shaft axis ω Shaft speed α Tilt angle of the swivel ring / swivel disk m _k Mass e. Piston including sliding block (pair) mass of all pistons including sliding blocks m _sw mass of swivel ring r _a outer radius of swivel ring t _{ inner radius of swivel ring h height of swivel ring g density of swivel ring

V Volume of the swivel ring ßi Angular position of the piston i

Z _; Acceleration of the piston i

F _mi Mass force of the piston i (including sliding blocks) M (F _mi ) Moment due to the mass force of the piston i

M _k moment due to the inertia of all pistons M _sw moment (or installation moment of the swivel ring / swashplate) as a result of the deviation moment (J _YZ )

When selecting the parameters for achieving the desired torque ratio, according to the invention the center of gravity position should largely have no influence. That When calculating the governing moment of deviation, the proportion of Steiner to be considered for the center of gravity is essentially

y _s z _s m = 0

In this case, the coordinate z _s lies in the direction of the shaft axis and the coordinate y _s perpendicular thereto and perpendicular to the tilt axis x _{s of} the swash plate (x _s is, of course, also = 0).

The moment of deviation J 'including Steiner proportion is too

J'yz = JYZ Ys + ^Z s ^SSL

According to the specified derivation for a swash plate in ring form, the parameters governing the control behavior were determined. From Tables 1 and 2, the values for two different preferred embodiments of inventive compressor can be removed.

Table 1:

Tipping moment determination for the swash plate of a first preferred

Embodiment of a compressor according to the invention

Swash plate variant 1

Table 2:

Tilting torque bestimavung for the swash plate of a second preferred

Embodiment of a compressor according to the invention

Swash plate variant 2

As a design criterion, as already mentioned, the ratio J _y / m _{k tot} or J ₂ / m _k makes sense, regardless of the refrigerant (which may be, for example, CO ₂ , Rl 34a, Rl 52a, etc.), the moment ratio

M _sw > M _{k] sat}

and thus characterizes the control behavior of the compressor engine. As can be seen from the two tables, the preferred point from guide forming a compressor according to the invention, a ratio J _j _k _ ./m _tot of more than 1000 mm ² or more than 1500 mm ^2, while the ratio J ₂ / m _{k ges} in both cases, well over 2000 mm ² , in the second preferred embodiment, even in about 3000 mm ² . In Fig. 3, the control characteristics of a compressor according to the invention for the Refrigerant CO ₂ and a spring rate of the return spring of 30 N / mm each for a maximum speed (in the present embodiment 8000 r / min) and a minimum speed (1000 r / min) for the operating points

- suction pressure ps = 35 bar; Compression pressure pd = 130 bar

Suction pressure ps = 50 bar; Compression pressure pd = 100 bar and suction pressure ps = 20 bar; Compression pressure pd = 70 bar

shown. The (not shown) control characteristics of a lying between 1000 rpm and 8000 rpm speed between the respective curves with the corre sponding suction or compression pressure. As can be seen from FIG. 3, the control characteristic curves for the rotational speed 8000 rpm for the three different operating points intersect the x axis (on which the tilting angle of the swash plate or the geometric stroke volume of the compressor is plotted) at approximately half the maximum tilt angle, which in the present preferred embodiment is about 20 °. For exactly one speed, the intersection with the x-axis can be constructively set, the other operating points include smaller deviations thereof, with control characteristics of the same speed and different operating points are shifted approximately parallel to each other.

4 shows control characteristics for an operating point (suction pressure ps = 35 bar, compacting pressure pd = 130 bar) for different rotational speeds, namely 1000 rpm, 2000 rpm, 4000 rpm and 8000 rpm , wherein the spring constant of the return spring 30 N / mm. As can be seen from the figure, reaching an angle of maximum deflection of approximately 20 ° is easily achievable for speeds of less than or equal to 4000 rpm, while at 8000 rpm only an angle of maximum deflection of approximately 14 ° is achievable can be achieved. Accordingly, reaching a maximum Kolben¬ stroke is possible up to speeds of 4000 rev / min, possibly even 5000 rev / min, while for larger speeds, the angle of greatest deflection of the swash plate is reduced. By increasing the spring constant of the restoring spring or else by increasing the inertia of the swashplate in relation to the piston mass, a compressor would also be achievable in which a maximum piston stroke can not be achieved even at a speed of 4000 rpm.

The tendency described above can be seen in Fig. 5, in which the control characteristics for the same operating points as in Fig. 4, but for a spring constant of

60 N / mm are shown. As can be clearly seen, the illustrated curves show a behavior that favors compressor attenuation. In the context of the present Invention has been recognized that at the operating point present here with a suction pressure of ps = 35 bar and a compression pressure pd = 130 bar an increase in the spring constant of 30 N / mm to 60 N / mm brings a control characteristic with it, which is slightly cheaper than at a smaller spring rate. On the other hand, as has been recognized according to the invention, for other operating points, for example a suction pressure ps-20 bar and a compression pressure pd = 70 bar (see Fig. 3), an increase in the spring constant is unfavorable since the control characteristics have a greater slope auf¬ would show. The intersection with the x-axis would already pay for smaller Dreh¬. Summarizing the above explanations, it has been found that according to the invention it has been recognized that spring rates of less than 60 N / mm, in particular spring rates of approximately 30 N / mm or possibly even smaller, are advantageous for the return spring.

As an alternative to the variation of the spring rate or, if appropriate, of course, in addition to this, the inertia of the swashplate can be increased. FIG. 6 again shows the control characteristics for a suction pressure ps = 35 bar and a compression pressure pd = 130 bar for the various rotational speeds at a spring constant of 30 N / mm and at increased mass inertia of the swashplate. As shown in FIG. 6 can be removed, in turn results in the desired course. The information on the geometry of the swash plate, which has a control characteristic, as shown in Fig. 6, can be found in Table 2 above.

Both of the swash plate geometries indicated in Tables 1 and 2 are, as can be seen from the figures explained above, suitable for displaying the desired control behavior.

Finally, FIG. 7 shows, analogously to FIG. 3, the known three operating points at a rotational speed of 1000 rpm and 8000 rpm. Desired for a compressor in about an arrangement of the control characteristics according to Figures 3 and 7 with the specified inertia of the swash plates according to Table 1 and Table 2. The Regelkenn¬ lines from the diagram of Fig. 3 show in comparison to the control characteristics FIG. 7 shows the desired effect in a comparatively weaker form, whereas the effect in the control characteristics according to FIG. 7 is more pronounced. However, in both embodiments it is the same that the control characteristics for high speeds have an intersection with the x-axis, which means that the angle of maximum Aus¬ steering for high speeds is less than the angle of maximum deflection for nied¬ rige speeds. In particular, it is desirable that the control characteristics for speeds have such an intersection above about 4000 U / min, ie reduce the angle of maximum deflection of the swash plate. At high speeds, it is desirable to limit the stroke volume to about 50% or less, with high speeds as noted above being about 8000 rpm in modern compressors.

It should be noted that the Abregein of the compressor would also be achievable by a control intervention, which in addition to the temporal inertia, which includes the control intervention, also ener¬ Tische losses play a major role here. During heavy acceleration of the vehicle and operation of the compressor at full load, the compressor operation initially (at least until the regulation corrected this again and the stroke volume is reduced) requires a very high torque, which is of course extremely undesirable, in particular during overtaking of the vehicle. In addition, the safety is increased in a compressor according to the invention, since disturbances of the control valve, for example, by contamination, blocking of the valve seat, icing or the like impair or hinder a control intervention. A strong increase in pressure, especially in high-pressure refrigerants such as CO ₂ , is very easily a security risk in such a case. Therefore, it makes sense to make at high speed larger tilt angle of the swash plate not reachable.

It should also be noted that Figures 3, 4, 5, 6 and 7, which relate to compressors in which the high-pressure refrigerant CO ₂ is used, qualitatively selbst¬ course also for other refrigerants, such as R134a, R152a etc ., can be used. Only the y-axis of the diagrams would have to be adjusted with respect to the indicated pressures.

It should also be noted that the desired control characteristic (with points of intersection of the corresponding curves with the x-axis) is achieved essentially by a suitable selection of M _sw and M _k . The fine adjustment of the desired Regel¬ characteristic can also be done by other means, such as a suitable selection of the spring constant of the return spring.

Finally, reference is made to Fig. 8, in which the interaction between the tilt angle of the swivel or swash plate and the pressure in the engine room or the differential pressure between the engine and the suction chamber is shown as a function of various parameters. Of Fig. 8 can be the

Control characteristics of a compressor according to the invention when using various additional devices which a force on the swash plate exercise, recognize. With the votstehend referred to as additional facilities facilities are meant in the presently discussed preferred embodiments of a compressor according to the invention means which are associated with the compressor in addition to a device for adjusting or for varying the engine room pressure and in addition to a return spring. At this point it should be noted that in addition to geometric considerations regarding the moment distributions, of course, other tilting of the tilting disc influencing or limiting devices, ie means which exert, for example, a force on the swash plate, are included in the basic idea of the present invention. These can be in detail in addition to the aforementioned return spring an actuator, a control piston, a centrifugal force-dependent actuator, another spring or a throttle point with variable or constant cross section. A throttle point with a variable cross section is conceivable, in particular in the form of a throttle point, which can be varied by means of an actuator, that is to say an actuating piston. It should be noted that within the scope of the invention, both individual of the above-mentioned measures as well as a plurality of measures or devices are included in combination. The corresponding control characteristics can be taken from FIG. 8 (as already mentioned above).

In detail, it can be seen from Fig. 8, that at an increase in the spring constant of the return spring or by the use of a possibly further actuating force, i. Thus, for example, by using an actuator, a steeper control characteristic can be achieved. Furthermore, it can be seen from FIG. 8 that a throttling on the suction side, for example by means of a variable or even fixed cross section, results in a curve shifted parallel to lower pressures compared to the control characteristic without additional actuating force. An analogue control characteristic results when the return spring is preloaded. By the measures described above, in particular the desired control characteristic with intersections of the corresponding curve with the X-axis at the desired location can be generated in a simple manner, the variety of possibilities a wide range of control (depending on the application of the compressor) allows. Depending on the wishes of the user, one or more measures can be combined and thus any desired control characteristics can be achieved.

Although the invention is described on the basis of exemplary embodiments with a fixed combination of features, it nevertheless also encompasses the conceivable further advantageous combinations of these features, as they are particularly, but not exhaustively, described by US Pat Subclaims are specified. All features disclosed in the application documents are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

Claims

"Axial piston compressor" claims

1. Axial piston compressor, in particular compressor for the air conditioning of a motor vehicle, comprising a housing and a housing arranged in the driven via a drive shaft compressor unit for sucking and compressing a refrigerant, wherein the compressor unit in a cylinder block axially reciprocating piston and the piston driving, rotating with the drive shaft swash plate (oblique, swash plate or swivel ring) comprises, characterized in that the tilting behavior of the swash plate is so self-limiting effect that at high speeds of the compressor, especially at very high speeds or the maximum speed, the angle maximum deflection of the swash plate is smaller than the angle of maximum deflection α _max at low speeds of the compressor.

2. A compressor according to claim 1, characterized in that the geometry and dimensioning of all translationally moving parts, such as axial piston, piston rod or sliding blocks, od. Like., On the one hand and all rotationally moving parts, such as swash plate, driver od. Like., On the other hand so are that for predetermined tilt angle of the swash plate, in particular between a predetermined minimum tilt angle and a predetermined maximum tilt angle, the moment M _k due to the translationally moving Mass, in particular the piston, if necessary, including sliding blocks, piston rods od. Like., Is chosen smaller than the moment M _sw due to Deviations¬ moments, ie as the moment due to the inertia of the swash plate, that at high speeds of the compressor, in particular at very high speeds or at a maximum speed, the angle of maximum deflection of

Swing plate is smaller than the angle of maximum deflection ct _max at lower speeds of the compressor.

3. Compressor according to one of the preceding claims, characterized by at least one device which exerts a force on the swash plate.

4. A compressor according to claim 3, characterized in that the at least one means for exerting the actuating force is assigned to the compressor in addition to a device for adjusting the pressure in the engine room.

5. A compressor according to claim 3 or claim 4, characterized in that the at least one means for exerting the actuating force comprises an actuator or a control piston.

6. A compressor according to any one of claims 3 to 5, characterized in that the at least one means for exerting the actuating force comprises a centrifugal force-dependent actuator.

7. A compressor according to any one of claims 3 to 6, characterized in that the at least one means for exerting the actuating force comprises a spring, in particular in addition to a return spring.

8. A compressor according to any one of claims 3 to 7, characterized in that the at least one means for applying the actuating force comprises a throttle point.

9. A compressor according to claim 8, characterized in that the throttle point is arranged on the suction side of the compressor.

10. A compressor according to claim 8 or claim 9, characterized in that the cross section of the throttle point by means of an actuator, in particular adjusting piston is variable.

11. A compressor according to claim 10, characterized in that in the engine room of the compressor prevailing pressure (P _c ) and / or prevailing at an outlet side pressure (P _D ) as a control variable for the actuator, in particular control piston, are used.

12. A compressor according to claim 10 or claim 11, characterized in that that the actuator internally, in particular via a magnetic coil or the like. Device, is regulated or controlled.

13. A compressor according to claim 8 or claim 9, characterized in that the throttle point has a constant cross-section.

14. A compressor according to any one of the preceding claims, characterized in that the center of gravity of the swash plate is on the tilting axis thereof.

15. A compressor according to any one of the preceding claims, in particular claim 14, characterized in that the tilting axis of the swash plate on a central axis of the drive shaft Hegt.

16. A compressor according to one of the preceding claims, characterized in that the swash plate is annular, i. is designed as a pivot ring.

17. A compressor according to any one of the preceding claims, characterized in that the angle of maximum deflection of the swash plate in the range of small and medium speeds up to about half the maximum speed of the compressor, in particular in a range of 0 to 4000 revolutions / minute an angle α _max , while at the maximum speed of the compressor corresponds approximately to an angle of α _max / 2.

18. A compressor according to any one of the preceding claims, characterized in that the swash plate for speeds from about 4000 revolutions / minute to 5000 revolutions / minute is no longer up to an / the angle α _{max is} pivoted.

19. A compressor according to any one of the preceding claims, characterized in that the limitation of the pivot angle for increasing speeds of the compressor is stronger.

20. A compressor according to any one of the preceding claims, characterized in that a ratio of Deviationsmoment in the y-direction and the total mass of all translationally movable parts such as pistons, optionally sliding blocks and the like.,

_{Y y} / m, at least about 1000 gmm ² / g, in particular more than 1500 gmm ² / g.

21. A compressor according to any one of the preceding claims, characterized in that a ratio of Deviationsmoment in the z-direction and the total mass of all translationally movable parts such as pistons, optionally sliding blocks and the like.,

J _z / m _k , at least about 2000 gmm ² / g, in particular more than 3000 gmm ² / g.

22. Compressor according to one of the preceding claims, in particular according to claim 4, characterized in that one or the return spring has a spring constant of less than about 60 N / mm, in particular less than 30 N / mm.

23. A compressor according to one of the preceding claims, characterized by a speed-dependent stop which limits the angle of maximum deflection of the swash plate in dependence on the compressor speed.