EP2165075B1 - Reciprocating piston engine - Google Patents

Abstract

A reciprocating piston engine, particularly a coolant compressor for motor vehicles, includes at least one piston movably supported in a cylinder. A pivot element in the form of a pivot ring is supported on a guide body attached to a shaft in an axially movable fashion such that the pivot element can execute a pivot motion. The pivot motion causes movement of the at least one piston. Spring forces of at least one return spring act on the pivot element in the direction of a start position in which the pivot element is pivoted at a starting pivot angle to a plane on which the rotary axis of the shaft stands upright. At least one further spring element acts on the return spring with an initial tension when the pivot element is in the start position.

Description

The invention relates to a reciprocating engine according to the preamble of claim 1.

There are known reciprocating engines, which serve in particular as a refrigerant compressor for controlling the passenger compartment temperature in motor vehicles. Such reciprocating engines have at least one piston movably mounted in a cylinder bore, which is set in motion by means of a pivoting element mounted pivotably on the drive shaft of the reciprocating piston engine, which piston is arranged in a drive chamber. The pivoting element is connected both to an axially guided on the drive shaft of the reciprocating piston guide body and via a driving pin with the drive shaft. In a known reciprocating engine is also provided that spring forces act at least one return spring on the pivot member. The spring forces act in the direction of a starting position of the pivoting element in which it is pivoted at a starting pivot angle to a plane on which the axis of rotation of the drive shaft is perpendicular. The swivel element of the refrigerant compressor, which is preferably designed clutchless and thus runs along with the drive shaft of a motor vehicle, must have a speed-dependent minimum starting swivel angle, so that the swivel element can swivel at any time, if the refrigerant compressor is to provide a specific cooling capacity. In order to achieve a wide spread of the control range of the compressor as a function of the engine pressure change, the return spring must have the highest possible spring stiffness. It has become the known reciprocating engines, however, shown that a high spring stiffness of the return spring prevents easy pivoting of the pivot member.

From the DE 198 04 084 A1 is a generic reciprocating engine with a mounted on an axially displaceably mounted on a shaft guide body pivoting ring out. The claim 1 is delimited in the preamble to this document. The pivot ring can perform a pivoting movement, by which a movement of at least one piston is effected. Furthermore, a return spring is provided for acting on the swivel ring with spring forces acting in the direction of a starting position. In the start position, the swivel ring is pivoted at a starting swivel angle to a plane on which the axis of rotation of the shaft is vertical. The return spring acts directly on a first end face of the guide body, while a further spring element acts on a first end face opposite the second end face of the guide body. That is, the return spring and the further spring element act on the guide body with spring forces directed in the opposite direction. This has the consequence that the return spring is biased by the further spring element, when the pivot ring is in its start position.

It is an object of the invention to provide a reciprocating engine of the type mentioned, which can be made more compact.

To solve this problem, a reciprocating engine is proposed which has the features mentioned in claim 1. This has, in addition to a return spring at least one further spring element, which the return spring with a bias acted upon when the pivoting element is in its starting position. This embodiment allows the swivel element, preferably designed as a swivel ring, to swing out easily and unhindered when the reciprocating piston engine, such as, for example, a refrigerant compressor, which is referred to below as KMV, is switched on for a motor vehicle. Vibrations during startup of the pivot element or start-up delays are practically impossible. The reciprocating engine is characterized in that the return spring and the at least one further spring element between the guide body and the shaft of the reciprocating engine are arranged. This results in a particularly compact design of the reciprocating engine.

Particularly preferred is a reciprocating engine, which is characterized in that the at least one further spring element is a curved disc. The further spring element preferably has a lower spring stiffness than the restoring spring, so that the pivoting element starts particularly easily and results in a spring force characteristic which changes from a flat characteristic to a steeper linear spring characteristic. Thus, a progressive spring force curve is created, wherein at the start of the reciprocating engine, the pivoting element has to overcome a small spring force.

Also, a reciprocating engine is preferred in which the return spring is designed as a helical spring.

Further preferred is a reciprocating engine, which is characterized in that at least one stop element is provided which predetermines the starting pivot angle of the pivoting element. at the stop element is preferably a spring assembly or at least one disc spring, but other spring elements may be provided.

In a further preferred reciprocating engine, the return spring has a lower spring stiffness than the stop element. This ensures, in particular, that the return spring does not pivot the pivoting element against the force of the stop element into a pivoting angular position which has a smaller pivoting angle than the starting pivoting angle.

Finally, a reciprocating engine is preferred, which is characterized in that the at least one further spring element is arranged in series with the return spring. Preferably, it is also provided that the at least one further spring element together with the return spring at an increasing pivot angle produces a progressive spring characteristic with low starting spring force, which reflects the advantageous starting characteristics of the reciprocating piston engine proposed here.

Figur 1

eine perspektivische Darstellung einer Baugruppe einer Hubkolbenmaschine;

Figur 2

eine vereinfachte Schnittdarstellung einer Baugruppe gemäß Figur 1;

Figur 3

eine Schnittdarstellung eines weiteren Federelements, und

Figur 4

eine Draufsicht auf ein weiteres Federelement gemäß Figur 3.

The invention will be explained in more detail below with reference to the drawing. Show it:

FIG. 1

a perspective view of an assembly of a reciprocating engine;

FIG. 2

a simplified sectional view of an assembly according to FIG. 1 ;

FIG. 3

a sectional view of another spring element, and

FIG. 4

a plan view of another spring element according to FIG. 3 ,

FIG. 1 shows an assembly of a reciprocating engine with a pivot member 1, a shaft 3 and a guide body formed here as an exemplary guide body 5. The pivot member 1 is formed here as a pivot ring, but is also conceivable training as a pan or swash plate.

The pivoting element 1 is connected via a driving pin 7 with the shaft 3. The driving pin 7 engages with its upper, that is radially outer, end in a recess 9 in the pivot ring 1, wherein the pivot member 1 is pivotally connected to the driving pin 7 and can pivot around it.

The pivoting element 1 is additionally connected via bearing sleeves 11 and arranged therein, not recognizable pins, with the guide body 5.

The driving pin 7 fixed to the shaft 3 engages through a slot 13 of the guide body 5 so that it is rotated together with the pivoting element 1 upon rotation of the shaft 3.

As already stated, the guide body 5 is mounted axially displaceably on the shaft 3. The maximum displaceability of the guide body 5 on the shaft 3 is determined by the ends of the elongated hole 13 of the guide body 5, which cooperate with the driving pin 7 at a maximum displacement of the guide body 5. The guide body 5 is formed here as a guide sleeve, but other embodiments of the guide body are conceivable to the FIG. 1 to realize apparent functionality.

The shaft 3 is preferably clutchless, preferably via a belt drive, connected to the drive shaft of an internal combustion engine, for example, a motor vehicle and is therefore dependent on their speed at any time.

In the FIG. 1 shown assembly is arranged in a drive chamber, not shown here a reciprocating engine.

The pivoting angle α of the pivoting element 1, that is, the angle by which the pivoting element 1 is pivoted with respect to a plane on which the axis of rotation of the shaft 3 is perpendicular, is influenced on the one hand by the pressure forces acting in the drive chamber and by inertial forces and spring forces. Decisive here is above all the relative pressure between the drive-chamber-side pressure of the at least one piston and not shown here the prevailing on the opposite side of the piston suction-side pressure of the reciprocating engine.

The regulation of the pressure conditions between the drive-chamber-side pressure and the suction-side pressure of the piston preferably takes place via a control valve. The higher the drive-chamber-side pressure is set relative to the suction-side pressure of the piston, the smaller the stroke width of the piston and thus the delivery of the reciprocating engine.

Due to the influences described above, the pivoting element 1 during the rotation of the shaft 3 performs a pivoting movement with a variable pivot angle α relative to the plane E, resulting in an axial movement of the at least one piston and the guide body 5 results. The operation of a reciprocating engine is otherwise well known, so it will not be discussed further here.

FIG. 2 shows a simplified sectional view of in FIG. 1 shown assembly. Same parts are provided with the same reference numerals, so in so far as the description to FIG. 1 is referenced.

In FIG. 2 discernible are the pivoting element 1 and the guide body 5, which are connected to one another via the bearing sleeves 11, not shown here, and the pins arranged therein. Also recognizable is the shaft 3, with which the pivoting element 1 is coupled via the driver pin 7, not shown here.

Between the inner surface of the guide body 5 and the peripheral surface of the shaft 3, a return spring 15 is arranged here is designed for example as a helical spring. Between a perpendicular to the axis of rotation of the shaft 3 extending wall portion 17 of the guide body 5 and the return spring 15, a further spring element 19 is arranged. It is also conceivable to provide a plurality of spring elements 19 and to arrange them in series with the return spring 15. The spring element 19 biases the return spring 15 in the starting position of the pivoting element 1. It should be noted that the spring element 19 is softer than the return spring 15, so that lower forces are required to compress the spring element 19 than is the case with the return spring 15.

As in particular from the FIGS. 3 and 4 becomes clear, the spring element 19 is exemplified as a curved disc having an opening 21 for receiving the shaft 3. Here, the disc is bent along an imaginary diameter line quasi U-shaped. The spring element 19 thus encompasses quasi the shaft 3, wherein here, for example, the convex curvature of the spring element 19 to the wall portion 17 of the guide body 5 and its concave curvature to the return spring 15 shows. The diameter of the opening 21 of the spring element 19 is preferably selected so that the spring element 19 is axially displaceable on the shaft 3.

Out FIG. 2 discernible is still a stop element 23, which rests on the one hand on a locking element 24 which is inserted into a groove 3 introduced into the groove 25, and on the other hand on a retaining ring 29 which is axially movable in a wide introduced into the circumferential surface of the shaft 3 groove 27 is stored. The stop element 23 is executed here purely by way of example as a spring assembly, but it is also conceivable, instead at least one plate spring or provide a stiff, directly attached to the guide body spring.

FIG. 2 makes it clear that the stop element 23 is arranged outside of the guide body 5. The stop element 23 is arranged so that it holds the guide body 5 in a position in which the pivoting element 1 is in its starting position, in which it is thus pivoted at a starting pivot angle α _start to the plane E. The arranged in the groove 27 retaining ring 29 serves as a stop for the wall portion 17 of the guide body fifth

If sufficient force is exerted on the stop element 23 or on the securing ring 29 from the right, then the stop element 23 designed as a spring assembly and the securing ring 29 displace in the groove 27 until the securing ring 29 abuts against the left end of the groove 27. In this position of the guide body 5 and thus of the pivoting element 1, the pivoting element 1 is in its Mindesthubposition in which it is pivoted at a minimum angle α _Min <α _start to the plane E.

The guide body 5 is displaced maximally far to the left in this minimum lifting position.

In the minimum stroke position of the pivoting element 1, it is not readily possible to start, for example, a KMV, which has previously run depending on the speed of the internal combustion engine. Therefore, as described above, the stop element 23 must be arranged and designed such that it displaces the guide body 5 so far to the right along the shaft 3 that the pivoting element 1 at an angle α _start > α _min is pivoted to the plane E.

Therefore, the stop element 23 preferably has a higher spring stiffness than the restoring spring 15 and thus gives the starting position of the pivoting element 1, or its starting pivot angle α _start with respect to the plane E before. The slight inclination of the pivoting element 1 about the starting pivot angle α _start in a clockwise direction is in FIG. 2 not recognizable due to the dimensions.

If, therefore, the internal combustion engine is started and the KMV is switched on, the pressure conditions in the drive chamber change through the use of a control valve such that the swivel element 1 completes a pivoting movement with a swivel angle α> α _start relative to the plane E. The size of the swivel angle α is determined by the control valve, which regulates the pressure in the drive chamber. During the pivoting of the pivoting element 1, which otherwise leads to a higher piston stroke and thus to a higher flow rate of the reciprocating engine, a displacement of the guide body 5 takes place axially to the shaft 3. The guide body 5 shifts in FIG. 2 that is to the right, while the pivoting element 1 swings out counterclockwise and thus has a larger pivoting angle α than the starting pivoting angle α _start with respect to the plane E.

As already mentioned, while the maximum displacement of the guide body 5 to the right by the dimensions of in FIG. 1 shown elongated hole 13 limited. The pivoting element 1 can thus be pivoted up to a maximum pivot angle α _max with respect to the plane E, so that, should a higher flow rate, or a higher power of the air conditioner may be desired, the pivot angle α of the pivot member 1 in a range of α _start <α <α _max can pivot.

If the pressure forces in the drive chamber now cause the pivoting element 1 or the guide body 5 to be displaced from their starting positions, the spring element 19 and the return spring 15 are compressed by the displacement of the guide body 5. First, the force causes only a compression of the spring element 19, since it preferably has a lower spring stiffness than the return spring 15; the KMV can start so easily.

The return spring 15, which is biased by the spring element 19, begins to grip only in a further displacement of the guide body 5, wherein the spring force of the return spring 15, against which the guide body 5 is moved, preferably linearly increases.

From a certain spring force, the additional spring element 19 is completely compressed, and the spring force of the return spring 15 acts on the guide body 5 until it is deflected a maximum, the slot 13 thus abuts with its left end on the driving pin 7. At this moment, the pivoting element 1 has reached its maximum pivot angle α _max .

At higher rotational speeds of the internal combustion engine increases at constant pressure conditions in the drive chamber of the ejected flow of the reciprocating engine, so that the pivot angle α must be reduced if the cooling capacity is to be kept constant. This is done through an interplay among others the pressure in the drive chamber of the KMV, the resulting piston forces and the restoring torque of the swivel ring, so that the pivot angle α of the pivot member 1 is reduced and a displacement of the guide body 5 takes place to the left. The return spring 15 presses with its spring force against the wall portion 17 of the guide body 5, so that this is finally shifted back into its starting position, wherein the pivoting element 1 is again aligned at an angle α _start to the plane E.

At even higher rotational speeds of the internal combustion engine and a very small cooling capacity requirement, the swivel angle α must be reduced even further to a swivel angle α _Min ≦ α _start in order to ensure a constant flow rate. In this case, the guide body 5 is displaced against the force of the stop element 23 to the left, whereby the locking ring 29 also moves against the spring force of the stop element in the groove 27 to the left. The guide body 5 is displaced maximally far to the left when the retaining ring 29 abuts the left end of the groove 27. The pivoting element 1 is then in its minimum stroke position, ie where the pivoting element 1 is pivoted at an angle α _min to the plane E, or lies in this. Due to manufacturing tolerances, the minimum swivel angle α _Min can also assume values smaller than zero, wherein no lift is given at a swivel angle α _Min = 0. Between piston and suction valve then forms a pressure pad, which prevents the piston from starting against the suction valve.

All in all, the at least one further spring element 19 builds up compared to the return spring 15 to a much lower spring force, which is overcome at the start of the machine, so a easy, unhindered pivoting of the pivoting element 1 is ensured. Shortly after overcoming the small spring force of the spring element 19 can thus pass over the spring force characteristic in the steeper preferably linear spring force characteristic of the return spring 15. The spring element 19 and the return spring 15 thus produce together during pivoting, starting from small pivoting angles a progressive spring characteristic. The spring element 19 thus preferably has a lower spring stiffness than the restoring spring 15, so that a particularly smooth transition between the starting position of the pivoting element 1 at a starting swivel angle α _start and higher swivel angles α is given.

The present invention thus advantageously makes it possible by a further spring element 19, which acts on the return spring 15 in a start position of the pivot member 1 with a bias to realize a much improved start-up characteristic with much softer transitions of the individual spring forces and to avoid unwanted vibrations.

LIST OF REFERENCE NUMBERS

1

pivoting element

3

wave

5

guide body

7

Carrier pin

9

recess

11

bearing sleeves

13

Long hole

15

Return spring

17

wall section

19

spring element

21

opening

23

stop element

24

blocking element

25

groove

27

groove

29

circlip

e

level

D

axis of rotation

Claims (9)

1. Reciprocating piston engine, in particular for motor vehicles, with at least one piston supported in a moveable manner in a cylinder and with a pivot element (1), preferably embodied as a pivot ring, which is supported on a guide body (5) attached to a shaft (3) in an axially displaceable manner, such that it can perform a pivot movement, through which a movement of the at least one piston is effected, wherein spring forces of at least one return spring (15) act on the pivot element (1) in the direction of a starting position, in which it is pivoted at a starting pivot angle (α_Start) to a plane E, on which the rotation axis (D) of the shaft stands upright and wherein at least one further spring element (19) is provided, which acts on the return spring (15) with a preload when the pivot element (1) is located in its starting position, characterized in that the return spring (15) and the at least one further spring element (19) are arranged between the guide body (5) and the shaft (3).
2. Reciprocating piston engine according to claim 1, characterized in that the at least one further spring element (19) is a curved disk.
3. Reciprocating piston engine according to claim 1 or 2, characterized in that the at least one further spring element (19) has a lower spring rigidity than the return spring (15).
4. Reciprocating piston engine according to one of claims 1 through 3, characterized in that the return spring (15) is embodied as a coil spring.
5. Reciprocating piston engine according to one of claims 1 through 4, characterized in that at least one stop element (23) is provided, which sets the starting pivot angle (α_Start) of the pivot element (1).
6. Reciprocating piston engine according to claim 5, characterized in that the stop element (23) is embodied as a spring assembly or at least one belleville spring.
7. Reciprocating piston engine according to claim 6, characterized in that the return spring (15) has a lower spring rigidity than the stop element (23).
8. Reciprocating piston engine according to one of claims 1 through 7, characterized in that the at least one further spring element (19) is arranged in series to the return spring (15).
9. Reciprocating piston engine according to one of claims 1 through 8, characterized in that the at least one further spring element (19) together with the return spring (15) produces a progressive spring characteristic curve with increasing pivot angle.

Images