US 3525215 A
Description (OCR text may contain errors)
g- 19'70 HANS-JOACHIM CONRAD 3,525,215
COUNTER PISTON MACHINE PREFERABLY COUNTER PISTON MOTOR WITH HYDRAULIC DRIVING MECHANISM Filed July 22, 1968 5 Sheets-Sheet l pri or in Aug. 25, 1970 HANS-JOACHIM CONRAD 3,525,215
COUNTER PISTON MACHINE, PREFERABLY COUNTER PISTON MOTOR WITH HYDRAULIC DRIVING MECHANISM Filed July 22, 1968 I5 Sheets-Sheet 2 Z E; S Y 4 :5 :I %?9 5 f I: 1 2: 5 a i 2 g: 8
\I k 4 4 a 19 g- 1970 HANS-JOACHIM CONRAD 3, 215
COUNTER PISTON MACHINE, PREFERABLY COUNTER PISTON MOTOR WITH HYDRAULIC DRIVING MECHANISM Filed-July 22, 1968 3 Sheets-Sheet 3 22-- 7 7/- 23 4 4 4 4 L 4 4 2k Z Connecfec/ f0 f rofa/able d/lsp/a cer United States Patent 01 3,525,215 COUNTER PISTON MACHINE, PREFERABLY COUNTER PISTON MOTOR WITH HYDRAU- LIC DRIVING MECHANISM Hans-Joachim Conrad, Essen, Germany, assignor to Fried. Krupp Gesellschaft mit beschraukter Haftung, Essen, Germany Filed July 22, 1968, Ser. No. 746,674 Claims priority, application Gsrmany, July 22, 1967,
US. CI. 6019 4 Claims ABSTRACT OF THE DISCLOSURE A machine having two counter running pistons re spectively movably connected to first and second linearly movable displacer means, in which the second linearly movable displacer means has a smaller piston area and an oppositely located larger piston area the smaller piston area of which is hydraulically connected to said first displacer means while passage means establish communication between the larger piston area of said second linearly movable displacer means and a rotary displacer means.
The present invention relates to a counter piston machine, preferably counter piston motor, With hydraulic driving mechanism. The advantages of a counter piston machine, especially of a two-cycle counter piston motor, are well known. The counter piston motor yields a satisfactory combustion chamber, avoids the heat losses occurring on the cylinder covers, and permits a simple direct flow scavenging.
The invention is particularly directed to a counter piston machine with hydraulic driving mechanism as disclosed, for instance, in German Pat. No. 1,179,778, corresponding to US. Pat. 3,066,476-Conrad issued Dec. 4, 1962. A hydraulic driving mechanism according to the said patent is characterized in that a stroke displacer cooperating with a reciprocating machine element, and a rotating displacer connected with a rotating machine element are interconnected through a hydraulic linkage system. The pressure fluid delivered by said stroke displacer is split up into at least two partial flows. This split-up in partial flows is intended to compensate for all radial and axial pressure forces which are exerted by the pressure fluid upon the rotating displacer. Only the tangential circumferential forces remain which correspond to the torque and which act upon the rotating displacer.
With these hydraulic driving mechanisms, sealing elements are provided between the housing and the rotating displacer therein. These sealing elements are guided to be displaceable either in radial or axial or in any desired direction and form pressure chambers into which the partial flows lead which are delivered by the stroke displacer.
The invention will become more apparent from the accompanying drawings, in which:
FIG. 1 illustrates a two-cylinder counter piston motor with a hydraulic driving mechanism according to the prior art;
FIG. 2 is an axial section through the cylinders of a two-cylinder counter piston diesel engine with a hydraulic driving mechanism according to the invention; and
FIG. 3 is an axial section through the cylinders of a counter piston motor according to a modification of the present invention with a portion of a hydraulic driving mechanism.
Referring first to the prior art of FIG. 1, this motor will now be described with regard to the working cylinder on hce the left-hand side only. It is assumed that all functions of the other working cylinder on the right-hand side are the same as those on the left-hand side and that only its displacers run ahead or lag with a phase displacement relative to the stroke of the displacers on the left-hand side.
Referring now more specifically to FIG. 1 showing the prior art, a rotatable displacer 2 rotates in the housing 1 of the hydraulic driving mechanism, said displacer 2 being connected to the output shaft 3. Four sliding blocks 4 are slidably arranged in said housing 1 and seal the rotor with regard to the housing, thereby forming four pressure chambers. The two pressure chambers 5, 6 respectively associated with the left-hand working cylinder 4a are arranged diametrically opposite to each other.
The counter pistons of the gas sides 7 and 8 are connected through piston rods 9 and 10 to the stroke displacers 11 and 12 for feeding the liquid pressure means.
The upper stroke displacer 11 presses the liquid pressure means through a conduit 13 into the pressure chamber 5 of the hydraulic driving mechanism, whereas the lower stroke displacer 12 presses the liquid pressure means through a passage 14 of the hydraulic driving mechanism into the pressure chamber 6;
With an arrangement of this type it is assumed that the mass forces of the two counter pistons are of the same magnitude and that also the hydraulic losses in the pipeline 13 and in the passage 14 are of the same magnitude, so that at each time, the same pressure conditions will prevail in the pressure chamber 5 as in the pressure cham her 6. Only in this way is it possible that all radial and axial forces which act upon the rotary displacer and which are exerted by the pressure means, will be able mutually to cancel each other out or balance each other. It is furthermore assumed that the pressure transmission ratio between the gas pistons 7 and 8 and the stroke displacers 11 and 12 feeding the liquid pressure means is of the same magnitude.
This means a considerable limitation in many instances. It has been found above all by the gas pressure diagram that stroke displacers, which are connected to the rotary displacer by such hydraulic linkage, are caused to perform with oscillations or vibrations. Such oscillations or vibrations can occur if for any reasons only the two oscillating stroke displacers 11 and 12 together with the piston rods 9 and 10 associated therewith and the gas pistons 7 and 8 oscillate with different fundamental frequency. For instance, oscillations or vibrations can occur because the oil volume enclosed between the two counter-running stroke displacers is of different magnitude. Possibly said stroke displacers also in the hydraulic transmission and in the pressure chambers 5 and 6 associated therewith will produce pressure oscillations of different frequencies, and as a result there consequently occur also pressure vibrations of dilferent intensity. If these pressure vibrations however are not in phase and are not of the same intensity, then the rotary displacer is no longer free from radial and axial forces. The result is that it runs in a noisy manner and transfers forces to its bearing means. The latter fact is a considerable drawback.
It is an object of the present invention to overcome the above-mentioned drawbacks.
It is a further object of the invention to provide a counter piston machine of the above-mentioned general type which will prevent any unbalanced axial or radial forces from acting on the rotary displacer.
The invention is based on a counter piston machine with a hydraulic driving mechanism of the general type set forth above, and is characterized in that with a counter piston machine of this type, two stroke displacers respectively positively connected with counter pistons are 3 arranged in series in such a way that one of the stroke displacers will through a fluid column act upon the back side of the other stroke displacer, which latter by means of its front side alone acts upon the hydraulic linkage.
Thus, in conformity with the present invention, only one stroke displacer is directly connected by a fluid pressure medium to the rotating displacer of the hydraulic driving mechanism, whereas a liquid column acted upon by the other stroke displacer acts upon the back side of said one stroke displacer. Such an arrangement yields a number of advantages.
First of all, it is no longer necessary that the two stroke displacers oscillate together and at the same phase length, because these oscillations no longer have a disturbing effect upon the hydraulic transmission. The hydraulic transmission is acted upon only by the oscillations of the lower stroke displacer. These oscillations cannot exert any unbalanced axial or radial forces upon the rotating displacer, in view of the above-mentioned splitting up of the pressure fluid delivered by said stroke displacer.
With the arrangement according to the present invention, it is furthermore not necessary that the fluid medium pressures produced by the two stroke displacers of a working cylinder be of the same magnitude. Pressure variations which result from a different mass force of the two stroke displacers or from a different step-up ratio between the gas piston and the displacers delivering the liquid fluid medium, or from different flow losses will no longer have any influence upon the running of the hydraulic driving transmission.
A further advantage of the arrangement according to the invention consists in that the stroke of the two counter pistons does not have to be of the same magnitude. Instead, the strokes of the two counter pistons may be of different magnitude. The stroke of the lower stroke displacer and of the lower gas piston is determined by the stroke volume of the rotating displacer. The stroke of the upper gas piston, however, is determined by the stroke of the lower gas piston and by the surface ratio of the effected piston surface of the stroke displacers which enclose the liquid pressure medium therebetween. If a complete mass equalization or balance is desired, the products of the weight of each of the two stroke displacers and the respective strokes pertaining thereto must be of the same magnitude.
Referring now to FIG. 2 of the drawing illustrating an axial section through the cylinders of a two-cylinder counter piston diesel engine with a hydraulic transmission, the description of this embodiment will likewise be discussed only with regard to the working cylinder on the left-hand side of FIG. 2, similar to the description of FIG. 1. According to FIG. 2, the housing 1 contains a working shaft 3 having mounted thereon the rotating displacer 3. Four sliding blocks 4 are radially displaceably arranged in housing 1 in such a way that through the intervention of sealing strips 4b they engage the outer circumference of the rotating displacer 2 and also engage lateral covers of the housing (not shown). In this way the sliding blocks 4 seal off four pressure chambers. Each two oppositely located pressure chambers are acted upon by a lower stroke displacer of the two illustrated working cylinders. The actuation of two oppositely located pressure chambers is, however, the fundamental difference over that in FIG. 1. According to FIG. 1, the pressure chamber 5 is acted upon by the upper stroke displacer 11 through the passage 13, and the pressure chamber 6 is acted upon by the lower stroke displacer 12 through the passage 14.
With the arrangement according to the invention, however, both pressure chambers 5 and 6 associated with the left-hand working cylinder 4a are acted upon by the lower stroke displacer 12. More specifically, the pressure chamber 5 is acted upon by the lower stroke displacer 12 through a passage 17, whereas the pressure chamber 6 is acted upon by the lower stroke displacer 12 through a passage 14. The liquid pressure medium delivered by the upper stroke displacer 11 is passed into a pressure chamber 19 through a passage 18 on the back side of the lower stroke displacer 12. The said delivered fluid pressure medium then acts upon an annular surface 12a which equals the difference between the piston surface 12b of the lower stroke displacer 12 and the cross-section of the piston rod 10. If now in the combustion chamber 20 an ignition takes place, the two gas pistons 7 and 8 are driven away from each other, and these pistons now act through the stroke displacer 12 feeding the liquid pressure medium upon the rotating displacer 2.
With a driving mechanism of the illustrated type, for instance, the lower counter piston 8 with the piston rod 10 and the lower stroke displacer 12 is by gas pressure or the inertia force pressed against the fluid pressure medium. However, conditions of operation are possible in which this will not be assured. For instance, during the starting operation at which the speed is still very low, for instance, within the range of the lower dead center point, the inertia force is insufficient to press the lower piston safely against the liquid pressure medium. To this end, according to FIG. 1, there exists the possibility through the intervention of a conduit 15 to convey a gaseous or liquid pressure medium to the lower side of the lower stroke displacer in order to assure a safe pressing.
With the upper piston it is necessary at low speeds always to convey a gaseous or liquid pressure medium to the back side of the upper stroke displacer 11 through a conduit 16, because during the running operation, the pressing force of the upper piston acting upon the pressure medium is fundamentally lower than that of the lower piston. In this connection, it should be kept in mind that the lower piston acts always by its own weight upon the liquid pressure medium, whereas the upper piston has the tendency, due to its own weight, to move away from the liquid pressure medium.
Inasmuch as with the embodiment of FIG. 1 there exists the requirement that the liquid pressure will at all times be the same in the passages 13 and 14 and thereby in the pressure chambers 5 and 6, it is necessary that with this embodiment the pressure medium act upon the upper stroke displacer through the conduit 16 in order to compensate for twice the weight of the piston.
This is no longer necessary with the embodiment according to FIG. 2 because with this last embodiment the liquid pressure in the conduit 18 need by no means be as high as the fluid pressure in the passages 14 and 17. If, however, for instance during the start, upper and lower pistons have additionally to be pressed against the liquid pressure medium, it will suflice, with the embodiment of FIG. 2, if only the upper stroke displacer 11 has its back side acted upon by a liquid or gaseous fluid medium and is thus pressed against the liquid pressure medium in the conduit 18. The liquid pressure medium acted upon by the stroke displacer 11 is acting also upon the back side of the lower stroke displacer 12 and presses the latter against the liquid pressure medium in passages 14 and 17. The divided action according to FIG. 1 upon the back side of the lower stroke displacer 12 through conduit 15 is not necessary with the embodiment according to FIG. 2.
With the embodiment according to FIG. 3, in contrast to the arrangement of FIG. 2, the upper counter piston 7 is no longer through piston rod 9 directly connected to a stroke displacer for the liquid pressure medium. Instead, the upper counter piston 7 is connected through a transverse yoke 21 and two pull-rods 22 and 23 to two stroke displacers 24 and 25 which through the intervention of the liquid pressure medium in chamber 19 act upon the back side of stroke displacer 12. In order to assure that the stroke displacers 24 and 25 will under all conditions of operation be pressed safely against the liquid pressure medium of the hydraulic driving transmission, it is possible with the embodiment of FIG. 3 to cause a gaseous or liquid pressure medium to act through feeding lines 26 and 27 upon the back sides of the stroke displacers 24 and 25.
The invention is applicable in connection with counter piston motors and also with machine tools which work in conformity with the counter piston principle, for instance, two compressors and pumps. Preferably, a twostrokc-cycle operation may be considered. However, the invention is also applicable to four-stroke-cycle engines, for instance, with counter piston four-stroke-cycle compressors.
As shown in German Pat. No. 1,179,778 corresponding to U.S. Pat. 3,066,476Conrad issued Dec. 4, 1962, instead of being provided with radially displaceable sliding blocks, the rotating displacer may also be provided with axially displaceable sliding blocks.
It is, of course, to be understood, that the positive connection between the stroke displacers and the counter piston may also be eflected with the aid of elements which bring about a transmission of the piston movements, for instance, by means of linkages and transmissions. Furthermore, the invention is not limited to the specific designs illustrated in the drawings, but comprises numerous modifications, the scope of the invention being defined by what appears to those skilled in the art.
What I claim is:
1. A counter piston machine which includes: cylinder means, two counter running pistons reciprocable in said cylinder means, first and second linearly movable displacer means respectively rnovably connected to said counter running pistons, said second linearly movable displacer means having a smaller piston area and an oppositely located larger piston area, means for hydraulically connecting said first displacer means with said smaller piston area of said second linearly movable displacer means, rotatable displacer means, and passage means establishing communication between said larger piston area of said second linearly movable displacer means and said rotary displacer means for conveying fluid displaced by said second linearly movable displacer means to said rotary displacer means 2. A machine according to claim 1, which includes: piston rods respectively connecting said first and second linearly movable displacer means with said counter running pistons so that each of said first and second displacer means has a smaller piston area adjacent the respective piston rod pertaining thereto and located opposite a piston area larger than said smaller piston area by the diameter of the piston rod cross-section adjacent said smaller piston area, and chamber means arranged adjacent to and communicating with said smaller piston area of said second linearly movable displacer means and also communicating with said passage means, said passage means communicating with the larger piston area of said first linearly movab e displacer means.
3. A machine according to claim 1, in which said first linearly movable displacer means comprises at least two dilferential displacer pistons having the smaller piston area thereof in fluid communication with each other and with the smaller area of said second linearly movable displacer means, and which includes yoke means and piston rod means interconnecting said smaller piston areas of said two differential pistons with the counter running piston pertaining thereto.
4. A machine according to claim 2, which includes: conduit means communicating with the smaller piston area of said first displacer means and adapted to be connected to a source of pressure fluid.
References Cited UNITED STATES PATENTS EDGAR W. GEOGHEGAJN, Primary Examiner US, Cl. X41.