SE449894B - HYDRAULIC POWER MACHINE WITH CAM DRIVE - Google Patents

Description

449 894 force the pistons to move in accordance with a cam track.

In the past, engines have been developed which include one on a shaft mounted rotor, in which a plurality of radial cycles relieves are designed. Around the rotor of such an engine is a cam path arranged in the form of a ring with lobes on the inside. These lobes are in contact with parts of pistons in the cylinders, which parts protrude from the cylinders and are provided with lar.

As oil is added to the cylinders, the rotor and it move lobed ring relative to each other as a result of the forces exerted on the lobed ring of carbon warning rollers, which cooperate with the lobes. Consequently, the rotor is set in rotation, then the lobed ring kept stationary. In a similar way, it is lobed provided the ring in rotation, when the rotor is kept stationary. Although in theory such prior art engines can be fill the condition according to equation (1), this is not the case in practice, as this would require that the lobes have a shape with undercut parts, which can not be achieved in practice. Also for an approximation to the theoretically required the shape, the lobe shape is disadvantageous and gives rise partly very high Hertz loads, while with such an approximation increased shape of the lobes of the running characteristics of such an engine much else to be desired, even to such an extent, that in one in such a case a conventional piston and crankshaft motor may be used with better results.

Furthermore, the lobed ring, which is the largest of the engine part in terms of diameter and which requires very careful processing on the inside, expensive and relatively complicated.

The invention aims to eliminate the above disadvantages.

An engine of the type described above according to the invention one includes a peripheral rotor mounted on the shaft combs and enclosed by a housing containing cylinders, which ka are distributed radially symmetrically about the rotor and which contains pistons with parts, which are arranged to cooperate with the peripheral surface of the rotor, which has such a profile that the sum of the vats for curve S for all the working strokes of the pistons below 449 894 one lap is the same size at any given moment.

The invention is explained in more detail below with reference to display to attached drawings.

Fig. 1 schematically shows a previously known motor with a lobed ring, Fig. 2 schematically shows an embodiment of an engine according to the invention, Fig. 3 shows an example of a stroke increment pattern for an speech motors according to the invention, Fig. 4 schematically shows a variant of the engine according to Fig. 2, Fig. 5 is a schematic cross-sectional view of an example of an eight-cylinder engine according to the invention, Fig. 6 shows a section in the plane VI-VI in Fig. 5, Fig. 7 shows a detail of the engine according to the invention, Fig. 8 shows a variant of the detail according to Fig. 7, Fig. 9 shows a number of possible rotor profiles for a motor according to the invention, Fig. 10 shows a preferred profile for a rotor in a motor according to the invention and I ' Fig. 11 schematically shows in which way an engine according to the invention can be controlled hydraulically.

Fig. 1 shows an example of a previously known engine with a lobed ring. The engine comprises a housing 1, which contains the lobed ring 2. The ring 2 has inner lobes or combs and encloses a rotor with a shaft 3, on which a rotor body 4 is mounted, in which body a plurality of radial cycles reliefs 5 are designed. In the cylinders 5 there are pistons 6, which ka are spring-loaded outwards. The pistons 6 are provided with rollers 7, which cooperates with the lobed surface of the ring 2. About oil below pressure is applied under the pistons, a number of rolls exert pressure on the flanks of the associated lobes, and because of this are continued rotor body in rotation, if the lobed ring is held in place tionary. Although the engine shown has a large number of pistons, where each piston performs a large number of strokes during each revolution of the shaft, however, it is impossible for the engine to work on in a completely uniform way. This is due to the fact that the point between the rollers and the lobed ring only in the extension of the piston shaft in the upper dead center of the piston stroke. 449 894 point and in its lower dead center. As a result, is required for satisfaction of equation (1), that the lobes have a different shape, which, as previously stated, cannot be achieved in practice tiken.

The present invention offers a fundamental normally constructed engine, where the movements of the pistons in such a way that the ideal rotation becomes possible, with the occurring Hertz loads being relatively low.

Fig. 2 schematically shows the principle of the motor according to the invention. The motor comprises a rotor, which consists of a shaft 21 with a cam disc 20 with a radially symmetrical set-up cylinders around it, which cylinders are located in a house not shown. As shown by way of example, the cam disc has three chambers 2637, 28, while four cylinders 22-25 are used, which ka contains respective flasks 30-33. The pistons cooperate with the cam disc through rollers and fixed connecting rods 34.

Of calculations, which will be dealt with in more detail below, it appears that an engine according to the specified principles can work true uniformly. The required combat profile can achieved in practice in a relatively simple manner.

In order to satisfy equation (1), the beets are mutually aligned correctly. It should It is advisable to avoid that the engine has dead spots, which can lead to stop or start difficulties. This risk is imagined, especially not for slow-moving engines.

It follows that the engine should have at least two pistons, and that the number of combs must be different from the number of pistons.

The motor should also be able to rotate in two directions. It follows, that each of the chambers should be symmetrical and placed on the rotor shaft in a radially symmetrical manner.

The equation (1) can be satisfied in several ways. A pre- take the opportunity is to choose the path for each piston's working stroke such that the following equation applies: S GX) = bd + C (2), where b and c are constants. A beat pattern that satisfies this condition (2) corresponds to a rectangular stroke incremental pattern, for which it holds that dS / du = b (constant).

Fig. 3 shows a possible beat increment pattern for one number of engines.

Part a of Fig. 3 shows a rectangular stroke increment. diagram of a two-cylinder single-stroke engine. With express- a single-stroke engine is referred to herein as an engine whose pistons perform a bite stroke during each shoulder turn. This means that the camshaft has a camÅ In an n-stroke engine, each piston performs n working strokes during each shoulder turn, and the cam disc has n cams.

Fig. 3a shows that a single-stroke, two-cylinder engine in principle can work true uniformly, then the characteristic curve, which represents the stroke increments is rectangular, which means that during the working stroke of each piston is dS / dn constant. If each piston is selected to have a working stroke of 1800 and an ejection stroke of 1800 and the working of one piston stroke begins, when the working stroke of the other piston ends, applies as can be seen from the figure during a full revolution, the following tion: d S (1) / du + d S (2) / da = constant.

With such an engine, however, a rectangular increment is curve possible only if true uniform gait is sought vase. A disadvantage found in practice in a single stroke, two-cylinder engine is that, as a result of the manufacturing the working stroke of the two cylinders does not always work in practice correctly follow each other, which can either cause extremely high oil pressure peaks or that the oil pressure in both cylinders disappear completely in a short period of time, which also disturbs the true uniform running of the engine. Similar prob- can operate with multi-stroke engines comprising several cycles relieves with a rectangular incremental stroke curve.

A single-stroke, two-cylinder engine also has dead spots at Oo and 1800, which without extra measures and steps can give rise to starting difficulties. These extra measurements and steps show up involve the use of a device, which can give equal size elements such as the engine, which in practice is financially unjustified.

Finally, a single-stroke, two-cylinder engine can only provide limited torque compared to multi-stroke engines.

The same applies to single-stroke multiple-cylinder engines, with three or more cylinders the different pistons 449 894 pickles can be chosen so that they partially overlap, so that no dead points arise. The rotational defects occurs as a result of this overlap, can be corrected by to cause the stroke increment pattern to increase or decrease complementary in the overlapping parts of the work teams. The total the impact increment pattern for each piston is then, for example, trapezoidal format or sine-trapezoidal format, i.e. the trapezoidal shape has sloping sides, which are curved in accordance with a sine square. Even in this case, however, there is the disadvantage of relatively low engine torque.

Two-stroke engines can provide twice as much power the same number of cylinders and the same bore and stroke as motor and can also work true uniformly with a suitable selected stroke increment pattern. The two-stroke, four-cylinder however, the engine has dead spots, where all the pistons either is in the upper dead center or in the lower dead center the point. Here, too, only a rectangular stroke increment pattern possible.

The three-stroke, four-cylinder engines have such as schematically, no dead points are shown in Fig. 2 and offer except for a relatively large number of possibilities for choosing the form for the stroke increment pattern while maintaining the accuracy of rotation.

Part b of Fig. 3 shows a rectangular stroke increment pattern. for the four pistons in a three-stroke, four-cylinder engine as well as §dS / ä fl, from which it appears that E} dS / ad is constant in one such an engine during an entire rotor revolution.

Instead of a rectangular stroke increment pattern one can also, for example, choose a triangular stroke increment pattern, where for example dS / äd increases linearly for the first the cylinder from 00 to 300 and from 1200 to 1500 and from z4o ° to 27o ° and decreases linearly from 3o ° rill eo °, from 15 ° to 100 ° and from 27 ° to 300 °. ne other calves has a similar stroke increment pattern, each offset 300. Here too, 'Eds / dm is constant during an entire shaft revolution.

The part c in Fig. 3 shows a triangular stroke increment ~ pattern for a three-stroke, four-cylinder engine. The part c in fig. 3 shows that with a triangular stroke increment pattern can also peaks occur in Eds / da as a result of manufacturing tolerances. _ .. .._....._......_..._.__. .- ...._..-...... ... - _. _......_.__...__ ~ ......... 449 894 However, the consequences are much less significant than with a rectangular stroke increment pattern due to the fact that it fold, which occurs in the total stroke volume and thus in the rotation of the shaft is only part of the deviations occurs in such a case with a rectangular stroke increment pattern. In the latter case, deviations are of plus or minus 50% is' 2dS / then inevitable. The beneficial properties of a triangular stroke increment pattern compared to one rectangular stroke increment pattern applies in insignificantly smaller provided a sinz-shaped beat increment pattern and a trapezoidal one and a sinz trapezoidal incremental pattern.

Another advantage of a triangular stroke increment is pattern is, that the maximum piston acceleration has the lowest possible value. The beneficial properties of a woody, four-cylinder engine is also found in a three-stroke, eight-cylinder risk engine and generally in a three-stroke, 4n-cylinder engine, as can be seen from diagrams similar to those in Fig. 3. Of course n here an integer.

The part d in Fig. 3 shows a sinz-shaped stroke increment pattern for the four cylinders of a three-stroke, four-cylinder risk engine. Since 2 «dS / you must be constant, there is one sinz shape for the rising edge of the stroke increment diagram and a cosz shape for the falling edge or vice versa. V A three-stroke, four-cylinder engine is shown in Fig. 2. A three-stroke, eight-cylinder engine can be obtained easily by adding a cylinder between each cylinder pair thereof fy cylindrical motor.

Pig. 4, which is similar to FIG. 2, schematically shows a stroke engine according to the invention, where, however, 40 rollers are directly connected by means of a shaft 41 to the piston bodies. On this way the engine can be built in a more compact way. In place for rollers, balls can be used, which can be applied to the way.

According to the invention, it is also advantageous to use only bullets instead of pistons with rollers or bullets, with or without fixed connecting rods. Such an engine is shown schematically in Figs. 5 and 6. The stroke increment pattern is determined by the movement for the centers of the rollers or balls, and this movement is determined 449 894 mes in turn by the way in which the rollers or balls rolls along the rotor and therefore depends in part on the the radius of the balls. Conversely, this means that the rotor shape depends on the radius of the rollers or balls; When selecting the rotor form, it is further necessary to take into account the the radius of curvature associated with the Hertz loads, which partly determines the service life of the contact surfaces. It has found nits, that three-stroke motors according to the invention enable a highly advantageous rotor shape in this respect.

Fig. 5 is a schematic cross-sectional view of a three-stroke, eight-cylinder engine according to the invention, where balls are used such as flasks. Fig. 6 shows a section in the plane VI-VI in Fig. 5.

The engine shown comprises a housing 50 with eight cylinders 51. The cylinders 51 contain ball pistons 52-55. A shaft 56, on which a rotor 57 with three cams is formed or mounted row, is arranged in the house. The shaft and rotor can be made of an infected substance. The rotor can rotate both clockwise and counterclockwise. If the rotor rotates clockwise as indicated by the arrow 58, performs ball carbon warn 52 a working stroke and the ball pistons 53 an ejection stroke.

The piston 54 is in the lower dead center, while the piston 55 is in the upper dead center. ' Figures 5 and 6 show the rotor 57 with a flat contact surface on average. This is shown in detail and schematically in Fig. 7, where the flat contact surface of the rotor has the reference numeral 71 and a ball piston reference numeral 70. I It can be calculated in a manner well known in ball bearing technology, that the curved cross-sectional shape of the contact surface of the rotor, at 80 in Fig. 8, leads to a higher load capacity of the ball and rotor, whereby the working pressure in the motor can be higher. In practice for example, the radius of the concave contact surface of the rotor be from 1.02 to 1.05 times the radius of the ball depending on the ball diameter.

In addition to the factors already mentioned, the shape of the rotor depends on the desired stroke and on the diameter of the ball pistons. It is clearly, that the blow can not be much greater than half of the diameter of the ball pistons.

Fig. 9 shows the shape of the rotor edge with a ratio those between the maximum stroke and the ball piston diameter of 0.4, wherein 15, 5 » d449 894 the inscribed circle of the rotor has a radius of 1.5 times the ball piston diameter. The dashed line at 90 shows the shape of the rotor edge for a rectangular stroke increment pattern. At 91 is displayed with the dotted line the shape of the rotor edge for a sinusoidal oidic incremental pattern, while the solid line 92 shows sar the rotor edge shape for a triangular stroke increment pattern. Although none of these three rotor shapes would imply some manufacturing problems and even if they all would give one in practice suitable engine, however, it has been found, that with the the selected conditions are the form associated with it triangular stroke increment pattern, the most favorable.

This is partly a consequence of that, as previously stated with a triangular stroke increment pattern, the results of the strokes of different pistons, which do not follow each other exactly timed manner, much less powerful than with for example a rectangular stroke increment pattern. If not just the beginning or the end of a stroke is slightly offset in proportion to the ideal, as a result of manufacturing tolerances, without whole the stroke of one of the pistons is completed somewhat prematurely or too late, this results in a less significant disturbance of the accuracy with a triangular stroke increment pattern than with a sing-shaped or trapezoidal-shaped stroke pattern, when a triangular stroke increment pattern in general is less steep, so that in the absolute sense the deviations in the incremental increment is insignificant. Furthermore, these are deviations constant during the stroke increment pattern. In the latter case is the rotor edge between the cams is substantially straight.

If the maximum stroke is chosen to be slightly larger, namely 0.417 times the diameter of the ball piston, and the radius of The inscribed circle of the tower is chosen to be 1.25 times the ball piston diameter. meter, the rotor profile gets a positive curvature at each point, i.e. it is convex. An eight-cylinder engine with such a is shown schematically in Fig. 10.

It is observed, while maintaining good gait properties are a large number of rotor profiles suitable in practice. With reference to the above can the possible rotor profiles with a given choice of the number of cylinders, stroke increment patterns, maximum stroke, ball piston diameter and radius of the inscribed 449 894 10 keln is constructed mathematically or calculated with a suitable computer programs, and for simplicity are described and displayed not this in detail here. _ The engine according to the invention has been described here only with regard to details of essential importance to the inventive idea.

In a practical embodiment, for example, the engine according to the invention is provided with removable cylinder heads, which at the housing by means of screws, which simplifies assembly and maintenance. Furthermore, the cylinders or cylinders heads with lines for the supply and delivery of hydraulic fluid, and control means, driven by the motor shaft, arranged to ensure that the hydraulic fluid is the cylinders are delivered or discharged from them in the correct glances. ' An example of the way in which the supply and the delivery of the hydraulic fluid can be accomplished in a stroke, four-cylinder engine according to the invention is shown schematically. in Fig. 11. Each pair of opposing cylinders is controlled by means of a single four-way valve 110, 111. The slides can be actuated either directly by means of a control cam disc connected with or mounted on the rotor shaft, or by means of servo valves 112, 113, which is actuated by means of a similar control cam disc such as is shown. The pump for the hydraulic fluid is shown at P. An nan possibility is to use a well-known distribution plate or rotor.

An engine according to the invention can be constructed as one pump in a similar way to previously known piston motors.

Example A three-stroke, eight-cylinder engine according to the invention and comprising ball pistons with a triangular impact increment pattern, a ball piston diameter of 80 mm and a stroke of 32.5 mm can achieve with a maximum working pressure of 320 atmospheres a torque of 20,000 Nm. With a ball piston diameter of 250 mm and a stroke of 100 mm, a torque of 600,000 Nm is possible with the same maximum working pressure.

Larger moments as well as effects can be obtained with example- show a three-stroke, twelve-cylinder engine or by mounting 449 A894 11 of two or more cylinder blocks in a housing on a shaft with two or more cam discs next to each other or with a single one widened cam disc with several grooves side by side. With a such a three-stroke engine with two sets of eight cylinders a torque of 1,200,000 Nm can be obtained. ' It is also possible to place a number of cam discs on a shaft next to each other, the cam discs having different sizes plays and cooperates with ball pistons of associated cylinders. sets, each with ball piston diameters corresponding to them associated cam discs. In this way, a gearbox effect achieved by providing cylinder sets and no feature.

The service life of the engine is determined i.a. of the number of changes in the pressure or turns of the rollers or ball pistons. With a comparable power, this number is smaller with an engine according to the invention than for a previously known engine with a ring with lobes, so that the motor according to the invention has a longer service life.

Claims (9)

449 894 12 PATENT REQUIREMENTS A hydraulic piston machine capable of delivering a high torque to an output shaft while the machine is running at low speed, the machine comprising 4n pistons, where n is an integer, a rotor mounted on the output shaft and provided with three symmetrically arranged peripheral cams for control of the movements of the pistons, and a housing surrounding the rotor and forming radial cylinders which are evenly distributed around the rotor and each holds its own piston, characterized in that the peripheral cams of the rotor have such a shape that: during each rotor revolution the sum of the first the derivatives of the curves of the working strokes of the pistons with respect to the angular displacement of the rotor substantially constant; and for each piston, the stroke increment pattern formed by plotting the corresponding first derivative against the rotor angle has a triangular shape, the triangular stroke increment patterns for all pistons being congruent and isosceles. Hydraulic piston machine according to claim 1, characterized in that the peripheral surface of the rotor is free of concavities. Hydraulic piston machine according to claim 2, characterized in that the peripheral surface of the rotor is convexly curved over its entire extent. Hydraulic piston machine according to one of the preceding claims, characterized in that each piston consists of a ball. Hydraulic piston machine according to claim 4, characterized in that the peripheral surface of the rotor has a ball groove for the ball pistons, the ball groove in cross section being concave. . 449 894 13 Hydraulic piston machine according to any one of the preceding claims, characterized in that it comprises a plurality of similar, side-by-side, annular sets of cylinders, the pistons of the cylinder sets cooperating with a widened peripheral surface of a single rotor. Hydraulic piston machine according to claim 6, when dependent on claim 5, characterized in that the widened peripheral surface comprises individual concave ball grooves for each cylinder set. Hydraulic piston machine according to any one of claims 1-5, characterized in that it comprises a plurality of side-by-side annular sets of cylinders, each piston set of pistons cooperating with each of a number of identical cam discs, sonically placed side by side. side on a shaft, said cam discs forming the rotor of the machine. Hydraulic piston machine according to claim 8, characterized in that at least two cylinder sets have different cylinder diameters, the pistons of the cylinders cooperating with cam discs, which correspond to these diameters.