DE2004322B2 - Path-controlled radial piston machine with rotating cylinder star - Google Patents

Description

the speed and at the beginning and the end 15 acceleration and constant deceleration with each each piston movement has areas in which the piston kernel executes rare movement, characterized in that the Wiukelbereich increasing piston speed (0 _Of ) greater than the angular range of decreasing piston speed (0 _dc ) is that, furthermore, the angular range of increasing piston speed (0 _{O (} .) And the angular range of decreasing piston speed (0 _rfi .) Are whole multiples of the piston phase difference angle (θ,), that the angular range of constant piston speed (0 _fV ) is equal to zero or a whole multiple of the piston phase difference angle (0 ") and that the

Rotation angle range (ε _ν ε. ₂ ) without radial movement of the piston with an even number of pistons is equal to half the phase difference angle and this rotation angle range with an uneven number of pistons is equal to a quarter of the phase difference angle (© „).

40

The invention relates to a path-controlled radial piston machine with the features of the preamble of the claim.

Due to the large number of individual, each separately driven pistons, the greatest common multiple is the number M of pistons in hydraulic machines, depending on their mode of operation and the number of profile shafts N is. In the event that the common multiple of the number of pistons N and, which is the greatest common multiple of the number of pistons N and

Piston stroke the same.

In radial piston machines with rolling elements rolling on the trajectory at the outermost end, each « Piston, the course of the cam represents the envelope of the movement path of the rolling element center point This has the consequence that the elevations of the piston path are more curved than their valleys. These smaller curve radii of the curved path in the area of the highest elevations result in a substantial amount increased specific surface pressures in these cam track sections, through which the service life the cam and the balls is reduced.

According to a proposal that was not previously published (DT-OS 19 14 598), such high Herz surface pressures are reduced by increasing the area of constant acceleration and reducing the area of constant deceleration accordingly, which means that the radius of curvature is increased in the area of a curve track elevation and in the area of a curved path part is reduced accordingly. In certain designs of this radial piston machine, it is absolutely necessary to provide a phase of constant speed in each case in order to achieve a constant torque in motor operation or a constant pressure in pump drive. These conditions always exist when the ratio of the number of pistons M to I is an odd number, where

Fluctuations. To compensate for these power fluctuations, a path-controlled radial piston profile wave number M is equal to 1, the result is a machine in which each Kol

machine with a cylinder star and fixed cams so ben assumes a different position. At a special

known railway (GB-PS 11 22441), in which every away or inward stroke of the piston, a region of constant acceleration, a second region constant speed and a third constant deceleration region. Furthermore the cam track is designed so that a pressure change during an acceleration or deceleration period each piston by a pressure change in the opposite direction of a complementary design of this proposed radial piston machine Dwell zones are provided in the dead center areas of the individual piston paths, through which the other speed phases move change. Due to such residence times, however, it becomes necessary either to make special phases more constant Provide speed or the requirement of constant K-acceleration or constant Delay going off and these areas

Period of another piston is compensated. Since 60 to form a curve.

The object of the invention generated by the respective individual pressures is to provide a path-controlled

Adding the torques results in the appropriate design of the respective acceleration and Deceleration areas in connection with the areas of constant piston speed a constant Total power of the machine or a constant total torque, if this is used as a motor works.

To create radial piston machine of the type mentioned, with an even and odd number of pistons a constant output power (torque or pressure) with reduced surface pressure on the Provides curved track elevations, and in which the switching times to prevent pressure surges are longer are.

This problem is solved by the characterizing features of the claim. The magnification Jes area constant acceleration compared to; in a corresponding reduction of the area constant deceleration results in an asymmetrical speed diagram and has the consequence that üe curved path radii in the elevations enlarged are, whereby the surface pressure between the cam track and the piston ball is lower and the Life of the two elements is extended. This makes it possible to reduce the pressure of the To increase hydraulic oil and thus to increase the performance with the same dimensions.

A constant power, ie a constant total torque in motor operation and a constant pressure in pump operation, results from the length of the individual speed or acceleration and dwell areas in the speed diagram, which are related to the phase difference angle θ _ρ in the specified relationship. If in such a designed radial piston machine with an uneven number of pistons the angle of rotation range without radial movement of the piston, i.e. the dwell range, at the beginning and end of each extension and retraction stroke is chosen equal to half the phase difference angle 0 _t , then the output power is constant. The same can be achieved in a machine with an odd number of pistons if the dwell times of its cam path are equal to a quarter of the phase difference angle.

In the following the invention will be explained with reference to the embodiments shown in the drawings explained. It shows

1 shows an axial section through a radial piston machine,

FIG. 2 shows a radial section through the machine along the section line II-II in FIG. 1,

3 shows an enlarged section according to F i g. 2 with the general geometrical relationships between a piston and the cam track,

4 schematically shows the sequence of movements of a Piston ball on a known cam track as well as the torque or speed diagram over the rotor rotation angle,

Fig. 5 shows a curved path (excl.> Green line) the corresponding asymmetrical speed or torque diagrams,

F i g. 6 graphical derivation of the constant total torque of a radial piston machine,

F i g. 7 shows a torque diagram over the rotor angle of rotation with the piston dwell areas for a radial piston machine with an even number of pistons,

F i g. 8 one of the F i g. 7 corresponding diagram for a radial piston machine with an odd number of pistons.

In the radial piston machine shown in FIGS the hydraulic fluid is supplied under pressure through flow channels 1 or 2 and passed through a channel 3 to a cylinder 4, which has a steel ball arranged on a piston 5 6 presses against a cam track 7. The cam track 7 has an undulating track (FIG. 2). A control surface 10 switches the liquid column according to the piston position before a survey 8 or a recess 9 of the cam track. An outer control surface 11 is rigid on the A rotor 12 wedged onto a shaft 13 and an inner control surface 14 by means of a universal joint 15 attached to the housing 16. When the rotor 12 rotates, a relative movement occurs on the control surface 10 between the inner ring 11 and the outer ring 14. The control surface 10 contains openings the points which correspond to the elevations 8 and in the depressions 9 of the cam track 7. In engine operation the rotor 12 is thereby driven when oil enters the cylinder 4 under high pressure.

If in the general representation according to F i g. 3 the distance between the center O of the rotor 12 and the center O 'of the steel ball 6 with R and the angle between the perpendicular established at the point of contact of the ball 6 on the cam track 7 and the line OO' as pressure angle <*, then R a function of the rotor rotation angle Θ. When the rotor rotates through a pitch angle Θ _Γ , that is, for example, from an elevation vertex to

ao to the next peak of the elevation an outward and inward stroke of the piston. The relationship applies:

tga =

dR / άθ

The torque Γ of the force acting on the center of the sphere O ' around the rotor axis O is _{calculated with a force F 0} exerted on the piston by the fluid pressure P from the equation:

Γ =

dR_

~ άθ

Accordingly, the torque Γ is proportional to the piston speed dR / άθ, so that the torque diagram over the rotor rotation angle θ is similar to the diagram of the piston speed dR / de. Since only one piston travel delivers useful power, namely the radially outward piston stroke in engine operation and the radially inward piston stroke in pumping operation, only the speed ranges delivering useful power are considered in the following.

tet, which each correspond to a rotor rotation angle of half the curve path division & _c.

In the case of the in FIG. 4, the cam profile is an envelope curve a "'b (" c "' d '", which arises when the center of a steel ball of radius r moves on the piston stroke curve a " ft /' C ₁ " d " . As can be seen , the curve radius Q at the curve point a "' is smaller by the spherical radius r than the curve radius ρ at the point α". The curve a "b" C ₁ "d" represents the lift curve of the

Piston and was made by integrating the speed diagram below determined. The angle ί drawn in the symmetrical torque diagram of this FIG indicates the tendency of the torque increase. Füi

Different curve radii of the curved path elevations result in the same torque when di <of the torque line at _l c ₁ d of the areas enclosed in each case are the same. However, this is only possible if the angle of inclination Φ is changed in each case.

In Fig. 5, the curve path is solid with asymmetrical speed diagram and dashed the curve path with symmetrical

Speed diagram shown, with the piston stroke S and the rotor rotation angle range of constant piston speed being the same in both cases and the number of pistons M being 10. The derived from the symmetrical torque curve from _l c _i d locus of the moving path of the ball centers is given by a '6,' b "d {, so that the radius of curvature in the range of a survey Q ₁ - r is abcd For the extended drawn torque curve. The result is a geometric location for the center of the sphere at a 'b' c 'd ( and a curve radius in the area of an elevation at ρ ₂ - r, where this radius is q _s - r > ρ, - r. In the diagram, the curvature of the path in the area of an elevation is therefore smaller and the surface pressure between the ball and the curved path is reduced, which has a positive effect on the service life of the ball and the path surface.

When the torque curve becomes asymmetrical, the total torque fluctuates. However, it is constant if the following conditions are met:

With a pitch angle ö _c = 2 n / N of the curved path (N = number of elevations) and with

a piston phase difference angle S _p - - ^ - (M = number of pistons) of the machine described with reference to FIGS. 1 to 3

the area of constant piston speed

the area of constant piston deceleration

You ⁼⁼ "* * Sp,

the area of constant piston acceleration

S _ae = η

= τη η θ _ρ ,

individual torque curves are congruent, it is sufficient to prove that the total torque in the angle of rotation range zero 2; 0 Ξ> S _{c is} constant. The total torque at point θ = zero is given by

_3o ■ * ^ 5 ■ · max '§ · * max "·" \ * m

~ 3 T _m

Are the inclination angles of the torque curves αp, fg and hi for uniform piston accelerations If the value is equal to 1, then, in order to achieve a constant total torque, the angle of inclination of the torque curve jk in the region of uniform piston deceleration is −3, so that the total torque in this region is equal to the torque im Point O is. At the point θ = θ _ρ the torque curve hi disappears with the slope 1. The torque curve kc appears with the same slope. Instead of the deceleration torque curve / k with the slope - 3, there is a similar curve

ao // so that the total torque of 3T _{mo) C} is retained.

On the basis of FIG. 7 and 8, the dwell areas ε, and s _{t are} determined in the following, in which the piston is not moved radially in order to thereby achieve the

As to extend the switching times and shut off the Avoid hydraulic fluid in the cylinder and simultaneous opening of the cylinder connections. In the F i g. 7 and 8 is

the area of constant piston speed

& CV ⁼⁼ S 'Sp ₅

the area of constant piston deceleration

where 5 is zero or an integer and η and m are integers. The addition of these angular ranges results in the angular range of a positive piston stroke. The following applies:

Sac + S "+ S _de = ---

the area of constant piston acceleration

S _ac = nm-Sp and the residence areas c

C ₁ and E ₂ ■ The sum results in the following relationship:

m (n +

If this equation is fulfilled, then the total torque is also constant. This condition applies only for an even number of pistons M. The number of pistons can also be odd if dwell areas are provided at the beginning and end of a piston stroke.

In Fig. 6 is the total torque for one Radial piston engine shown with an even number of pistons and asymmetrical torque diagram. The motor has the following characteristics:

M = 10

s = 1 θ _ο . = Θ _Β

τη - 1 S ^ c ⁼ Sp

η = 3 β «= 3 S _p

The sum of the dwell areas is determined from this

This results in: In order to be able to use existing dwell areas e,

and f _z keep the total torque constant zn.

must with such a radial piston machine

SS with an even number of pistons each of the residence areas

be.

In a radial piston machine with an odd number of pistons, e.g. B. M = Il, the size is de Usage areas

In the torque diagram according to FIG. 6, ten trapezoidal torque curves abcd appear in a torsional angle range of 0 ^ θ ^ θ, each offset by the phase difference angle β _Ρ . Since the

ε, = ε, = each ,,.

In this case s is equal to zero or 1, and is determined according to the value of 5

Is can therefore have a curved path profile with low

ster surface pressure in the area of the respective elevations between the piston ball and the cam surface be constructed, through which a constant total useful power results and which a Shutting off the hydraulic fluid in the cylinder or

avoids direct flow by using the envelope is formed, which is created by the movement of the center of the ball on the stroke curve, which is created by integration the unbalanced torque curve satisfying the above equation is obtained.

In addition 5 sheets of drawings

509530 / «

Claims (1)

Claim: Path-controlled radial piston machine with rotating cylinder star, the even and odd May contain numbers of cylinders, central control pin and externally located multi-corrugated roller track on which the pistons roll by means of rolling elements and which is designed in such a way that that the speed curve that arises when one of the pistons interacts with it, Areas with a straight line increasing speed, If necessary, areas of constant speed, areas in a straight line decrease-up Due to the high speeds with which these radial piston machines run, they can] Problems arise in controlling the hydraulic pressure by means of to and from the individual cylinders To extend the very short filling and emptying times, especially at high speeds individual cylinder, it is known from US-PS 3046 95 (in addition to the areas of constant acceleration There is a tendency to provide separate areas for constant speed and constant deceleration in which there is no radial piston movement so that the individual switching times are dadurcl enlarge. In these two known radial piston machines, the areas are constant loading