KR100659682B1 - Long-piston hydraulic machines - Google Patents

Abstract

Smaller and lighter hydraulic pumps / motors provide significantly improved volumetric efficiency by pistons having a body portion reciprocating therein substantially the same as the axial length of each cylinder. A plurality of lubrication channels formed around each cylinder and traversing radially across its wall are each positioned such that they are almost always completely closed by their axial cylinders during the entire stroke of each piston. Each lubrication channel is interconnected to form one continuous lubrication passage as a whole inside the cylinder block and is not connected by a fluid "inlet" or fluid "outlet" passage. The lubrication channel is supplemented only by the minimal flow of fluid that enters from the valve end of each cylinder and passes between the cylindrical wall of each cylinder and the axial cylinder of each piston. Several embodiments have been disclosed in combination with various spring-supported hold-down assemblies.

Piston, Cylinder, Hydraulic Machine, Pump, Motor, Spring, Swash Plate, Lubrication

Description

Hydraulic Machine with Long Piston {LONG-PISTON HYDRAULIC MACHINES}

The present invention is a liquid hydraulic pump / motor suitable for use with relatively "heavy duty" automatic propulsion, for example for fluid storage and withdrawal of hydraulic transmissions and / or energy saving accumulator systems used in the movement of vehicles. It's about machines.
[Note: The term "liquid" is used to distinguish it from "gas" hydraulic pumps, for example pumps that compress air and / or other gases.]

Hydraulic pumps and motors are known and widely used and have a yellow double-stroke piston mounted in each cylinder formed in the cylinder block and circumferentially positioned at a first radial distance about the axis of rotation of the drive member. Many of these pump / motor machines can vary in displacement and usually come in two basic designs. That is, (a) any piston is reciprocated in a cylinder block that rotates with respect to a rotating swash plate which is inclined in various ways, or (b) these pistons are inclined and rotated in a variety of inclined and rotated surfaces. It reciprocates about a swash plate that is often divided to include a wobbler that rotates (ie, tilts only). Although the present invention is applicable to both of the above designs, it will be described in particular with regard to the improvement of the latter machine, which reciprocates in a cylinder block in which the piston is fixed.
As mentioned above, the present invention relates to a "liquid" (different from "gas") type hydraulic machine. Because liquids are incompressible, these two different types of hydraulic machines are fundamentally different, and the design of the gas compression machine is inadequate for use in liquid machines, and vice versa. Therefore, it should be understood that the following descriptions are all applicable to liquid hydraulic machines, and are mainly applied to high load automated machines as mentioned in the "technical field" above.

Hydraulic machines with fixed cylinder blocks must support and protect heavy rotating cylinder blocks. However, these lightweight machines require rotating and tilting swash plate assemblies that are not easy to mount and support. For high pressure / high speed operation, the swash plate assembly must be supported to allow relative movement between the head of the non-rotating piston and the mating flat surfaces of the rotating and tilting swash plate. As mentioned above, these prior art rotating swash plates are often divided into rotating and tilting rotor portions and tilting wobbler portions. The tiltable wobbler portion includes a flat surface mating with the head of the non-rotating piston. As is known, this relative motion follows various non-circular paths that change the tilt of the swash plate from 0 °.
In addition, a machine in which a cylinder block is fixed has conventionally been used to " dog-bone " extension rods to interconnect one end of each piston with a nutating-but-not-rotating wobbler. That is, a rod having two spherical ends) was used. One spherical end of the dogbone is pivotally mounted to the head end of the piston, while the other spherical end is typically pivotally mounted which should always be kept in complete and flat contact with the flat surface of the swash plate wobbler. Covered by a "shoe". This member is a fairly complex configuration and increases the manufacturing cost of the rotating swash plate of these lightweight machines.

In addition, dogbone rods are sometimes used to interconnect one end of each piston with an inclined (but not rotating) swash plate of a hydraulic machine having a rotating cylinder block. However, most of the above types of hydraulic machines have spherical heads at one end instead of dogbones as described above (likewise covered by a shoe member mounted in a conventional pivotal manner) and a non-rotating flat surface of a swivel plate. Use an elongated piston for effective contact with These elongated pistons are designed such that a substantial portion of the axial cylindrical body of each piston is always supported by the respective cylinder wall, even while the piston is at its maximum stroke. The additional support for these elongated pistons is designed such that the lateral displacement of each spherical piston head is minimal since the piston slides through the inclined and non-rotating swash plate as it rotates with respect to their cylinder block.

In general, these elongated pistons are primarily lubricated by so-called "blow-by", in which high pressure gas is forced between each cylinder wall and the circumference of each piston body as the reciprocating piston is driven by the high pressure fluid. do. This blow-by provides a good lubrication effect only if there is a gap allowing sufficient fluid flow between the cylinder wall and the elongated cylinder of the piston, and a blow-by is often sufficient to ensure good lubrication. Negatively affect efficiency. For example, a 10 cubic inch machine can use as much as 4 gallons per minute for blow-by. Although smaller gaps may be used to reduce blow-by, the reduction of the gaps is limited by the need for proper lubrication that increases with the magnitude of the load and pressure of the machine. Of course, such blow-by is obtained by using the fluid used in the driven or driven piston to perform the work. Therefore, in the above example, 4 gallons of fluid per minute used for blow-by lubrication lowers the volumetric efficiency of the machine.

The invention described below improves the volumetric efficiency of a machine with such an elongated piston, while at the same time simplifying the device used to maintain (a) proper lubrication of the piston and (b) contact between the piston and the swash plate. It is for.

The present invention discloses several embodiments of a hydraulic machine, all of which each slide to make sliding contact with an elongated piston reciprocating in a fixed cylinder block, a cylinder with a unique lubrication recess, and a rotating and tilting swash plate. It consists of a preferred combination of simple structural features, including a shoe that attaches directly without a dog-bone. It relates to two different hydraulic machines. These simple structural features exert synergy and (a) The efficiency is increased by 90% and (b) this increased mechanical efficiency can be easily rotated manually by hand, even if the drive shaft of a machine of size 12 cubic inches is fully assembled.
Each described hydraulic machine can operate as a pump or a motor. One side has a rotating swash plate which is fixed at an angle with respect to the axis of the drive member while being constantly rotated by the drive member of the machine, so that the piston always moves at the stroke set to the maximum. The rotating swash plate of the other machine has an inclination which can be varied within the angular range in a manner known in the art to control the stroke of the piston in the range which can be moved in the maximum direction in each direction. [However, those skilled in the art should understand that the present invention is also applicable to a hydraulic machine having a rotating cylinder and a rotating swash plate that does not rotate relative to the driving member of the hydraulic machine.]

In each machine according to the invention, each piston is an elongated piston having an axial cylinder which is preferably at least as long as the axial length of the reciprocating respective cylinder. Preferably, each piston also has a spherical head end in which sliding contact is effectively maintained with the flat surface of the swash plate of the machine by a shoe and a relatively simple device pivoted in a conventional manner. The axial length of each cylindrical piston body is always selected to minimize lateral displacement of the spherical first end of the piston. Therefore, the preferred piston of the present invention minimizes the lateral displacement of the advanced spherical end of the piston at all times while the machine is in operation while the part of the piston body where each piston is advanced at its maximum stroke and still supported inside each cylinder. It is a "long" piston that is long enough.
[Note: In order to facilitate the description of the present invention, each piston has an axial cylindrical portion and a spherical head end, and each cylinder has an open head portion where the valve end and the spherical head end of each piston are always advanced. It explains as having. Further, in all preferred embodiments each disclosed hydraulic machine (eg motor or pump) is paired with a similar hydraulic machine (eg mating pump or motor) to form a known "closed loop" arrangement, The high pressure fluid discharged from each pump is delivered directly to the inlet of the associated motor, and the low pressure fluid discharged from each motor is delivered directly to the inlet of the associated pump. As is already known, a portion of the fluid in the closed loop system continues to be lost in a "blowby" and recovered to a sump, and the fluid is automatically delivered to the closed loop from the sump by an air supply pump. To ensure that the fluid in the closed loop system is always maintained in a predetermined volume.]

According to the invention, each cylinder formed inside the cylinder block of each machine is provided with a respective lubrication channel formed on the cylindrical wall of each cylinder. This lubrication channel is always positioned so that each lubrication channel is almost completely closed by the axial cylinder of the piston during its entire stroke while the piston reciprocates in each cylinder. [Note: The movement of fluid in these lubrication channels is described in more detail in the following two paragraphs.] Each lubrication channel is formed on the outer circumference and preferably traverses each cylinder radially.

The fixed cylinder block of each machine is formed with a further plurality of passages which interconnect each of the aforementioned lubrication channels. The interconnection of all lubrication channels forms one continuous lubrication passage in each other within the cylinder block. Such continuous lubrication passages are formed throughout the cylinder block, and since the cylinders are aligned about the axis of rotation of the drive member, it is preferable to align them on the outer circumference across the respective cylinders and at substantially the same radial distance.

In a preferred embodiment, the continuous lubrication passage as described above is not connected by the fluid "inlet" passage or the fluid "outlet" passage, but instead is almost always completely closed by the cylindrical body portion of the piston while the machine is operating. do. Therefore, only the source that supplies the lubricating fluid to this continuous lubrication passage is the secondary minimum flow of fluid between each cylindrical wall of each cylinder and the axial cylinder of each piston. During operation, the lubrication passage is mostly filled by an initial minimum flow of high pressure fluid passing through the cylinder end of each cylinder and then passing between the perimeter of each cylinder wall and the body portion of each driven piston. This secondary minimum flow always effectively maintains high pressure inside the continuous lubrication passage. If desired, a plurality of sealing members, each positioned near the open end of each cylinder, selects a relatively complete seal to substantially eliminate blow-by between the body portion of each piston and the open head portion of each cylinder. This ensures that only a minimal blow-by from the lubrication passage exits through the open end of the cylinder. In practice, however, it has been found that only a relatively small blow-by from the open end of the cylinder moves past the elongated piston of the present invention, because the small amount of blow-by spray required for proper lubrication of drive shaft bearings, etc. This is because it is not necessary for the selective sealing member.

Nevertheless, the lubricating fluid in the closed continuous lubrication passage is constantly moved by the constantly changing pressure in each cylinder as the piston reciprocates. That is, as each cylinder pressure is reduced to low pressure at the return stroke of each piston, the high pressure fluid in the closed fluid passages is again induced between each cylinder wall and the outer periphery of each piston body to reduce the pressure of each cylinder. Move to the end. However, the lubricating fluid that is directed to the low pressure side is not "lost". That is, it is not a "blobby" and does not return to a sump to be supplemented to a closed loop hydraulic system by the supply pump. Instead, this low pressure lubricating fluid is returned directly to the closed loop without the use of an air supply pump, and the closed continuous lubrication passage is immediately replenished by the introduction of a similar high pressure blowby flow from the valve end of each boosted cylinder.

The lubrication passages described above provide adequate lubrication for high speed reciprocation of the piston while substantially reducing blow-by. In the successful operation of commercial prototypes made in accordance with the invention, the blow-by was reduced by 90%. In other words, the blow-by of a conventional commercial hydraulic machine is 4-5 gallons per minute, whereas the blowby of the prototype of the present invention was 0.5-0.7 gallons per minute, which significantly increases the volumetric efficiency of the hydraulic machine of the present invention. Can be.

As described above, the hydraulic machine in which the cylinder block is fixed can be manufactured in a small size and light weight in comparison with the hydraulic machine in which a conventional cylinder block of the same specification rotates. As a result of the improved lubrication of the elongated piston, the present invention makes it possible to use this compact, lightweight design to meet the high speed / high pressure specifications required for automobiles.

Furthermore, considerably simplified support assemblies are satisfied for the various rotating swash plates of the hydraulic machine of the present invention. Each of the support assemblies of the present invention may omit a dogbone that is generally mounted between the outer end of each piston and the nutating-only wobbler portion of a conventional rotary / tilt swash plate, and conventional The shoe is mounted directly to the spherical head of each piston to maintain an effective sliding contact with the flat surface portion of the swash plate by minimal spring bias, which minimizes the flow of fluid at the valve end of the cylinder of the pump. It is a force that allows effective sliding contact in the absence of pressure.

Two simplified support mechanisms are described below. The first simplified support mechanism includes a hold-down plate assembly deflected by a coil spring circumferentially positioned about the axis of rotation of the drive member of the pump. The second support mechanism is simpler, with each piston being provided by a minimum bias provided by a plurality of springs respectively located within the body portion of each piston between the body portion of each piston and the valve end of each cylinder. It only includes a conventional shoe mounted directly on the spherical head of the < RTI ID = 0.0 > The latter support mechanism is slightly more difficult to assemble than the former mechanism, but is fairly simple, light weight, and low in manufacturing cost.

An important feature of the present invention is to provide a hydraulic machine which is lighter and smaller than a conventional hydraulic machine having the same specification. In addition, as described above, it was found in the actual prototype test that the present invention provides a machine with significantly increased volumetric efficiency and glitchy efficiency. That is, the present invention provides a hydraulic machine with significantly greater volumetric efficiency while significantly reducing the weight and size of the machine, reducing manufacturing costs and simplifying assembly.

1 is a partial cross-sectional view of a hydraulic machine having a fixed cylinder block and a rotating / tilt swash plate with a fixed inclination, showing the features of the invention in which the cylinder block and the piston / swash plate interface are integrated.

FIG. 2 is a partial cross-sectional view of a fixed cylinder block taken along the virtual plane 2-2 and omitting some components in the hydraulic machine shown in FIG. 1.

3 is a partial cross-sectional view of a hydraulic machine having a fixed cylinder block and a rotating / tilt rotating swash plate with varying inclinations, illustrating the features of the present invention in which the cylinder block and the piston / swash plate interface are integrated.

4A and 4B are partial cross-sectional views of the swash plate tilted at + 25 ° in the swash plate and piston shoe hold-down assembly shown in FIGS. 1 and 3, with relative positions of the head end, shoe, and special washer of the piston; And a spring-tight hold-down member for deflecting each sliding shoe with respect to the flat surface of the swivel plate, FIG. 4A taken along virtual planes 4A-4A in FIG. 3, and FIG. 4B being virtual in FIG. 4A. It is taken along planes 4B-4B.

5A and 5B, 6A and 6B, 7A and 7B are the same views as FIGS. 4A and 4B when the rotating swash plate is inclined at + 15 °, 0 ° and -25 °, and FIGS. 5B and FIG. 6B and 7 are taken along the virtual planes 5B-5B, 6B-6B and 7B-7B of FIGS. 5A, 6A and 7A, respectively.

8 is a partially enlarged cross-sectional view showing one cylinder and piston of another hydraulic machine similar to that shown in FIGS. 1 and 3, showing a second simplified embodiment of a hold-down assembly held against a piston shoe.

The operation of a hydraulic machine of the type to which the present invention is applied is known and will not be described in detail. As noted above, each disclosed machine is a known " closed loop " hydraulic system with suitably paired pumps or motors.

<Hydraulic motor>

Referring to FIG. 1, a hydraulic motor 10 includes a plurality of fixed parts having a plurality of cylinders 14 (only one shown), in which a plurality of pairs of pistons 16 mate therein reciprocate between their retracted and advanced positions. Included cylinder block 12. Each piston has a spherical head 18 mounted on a neck 20 at one end of an elongated axial cylinder 22, in a preferred embodiment the elongated cylinder 22 of each piston. Is substantially the same length as each cylinder 14.

Each spherical end 18 fits inside each shoe 24 that slides over a flat surface 26 formed on a drive member, ie a surface of the rotor 28 that is fixed to the shaft 30 of the machine. . The shaft 30 is supported by a bearing in the bore 31 at the center of the cylinder block 12. The flat surface 26 of the fixed rotor 28 is inclined at a predetermined maximum angle (for example 25 °) with respect to the axis 32 of the drive shaft 30 and is supported by a suitable thrust bearing assembly 35. .

The modular valve assembly 33, which is secured by a bolt as a cap on the left end of the cylinder block 12, has a plurality of spool valves 34 (only one shown) that regulate the delivery of fluid entering and exiting the cylinder 14. It includes. As mentioned above, the hydraulic machine operates as a pump or a motor. In a preferred embodiment, the angle fixed swash plate machine shown in FIG. 1 operates as a motor. Therefore, during the first half revolution of the drive shaft 30, a high pressure fluid from the inlet 36 enters the valve end of each cylinder 14 through the port 37 and advances each piston completely out of its retracted position. In a closed position, and during the second half revolution, the low pressure fluid is withdrawn from each cylinder through port 37 and fluid outlet 39 as each piston returns to its fully retracted position.

In known methods, the fluid inlet 36 and outlet 39 are preferably connected to a paired hydraulic pump (eg, pump 110 shown in FIG. 3, described below) through suitable “closed loop” piping. The fluid pressure is such that the spherical end 18 and each shoe 24 are always deflected with respect to the flat surface 26. A series of advancing and retracting of each piston causes the rotor 28 to rotate the drive shaft 30. The flat surface 26 is fixed at the maximum inclination, and when the flow amount of the hydraulic fluid circulating through the closed loop through the inlet 36 and the outlet 39 is relatively small, the piston 16 reciprocates at a relatively low speed so that the drive shaft ( Allow 30 to rotate at a relatively low speed. However, as the flow amount of the fluid circulating in the closed loop increases, the reciprocating speed of the piston increases accordingly to increase the rotational speed of the drive shaft 30. When operated at the speed or pressure of the vehicle (eg 4000 rpm or 4000 psi), the lubrication of the piston is at a critical state and blow-by losses can also be significantly increased. The cylinder block 12 has been modified by the present invention in order to achieve such a demand for lubrication and reduction of blowby losses.

1 and 2, the cylindrical wall of each cylinder is traversed radially across by a respective lubrication channel 40 formed on its outer periphery. The plurality of passages 42 interconnect all of the lubrication channels 40 to form a continuous lubrication passage within the cylinder block 12. Each lubrication channel 40 is substantially closed by the axial cylinder 22 of each piston 16 during the entire stroke of each piston. That is, the outer circumference of each cylindrical body 22 always acts as a wall surrounding each lubrication channel 40. Thus, even when the piston 16 reciprocates at maximum stroke, the continuous lubrication passages interconnecting all the lubrication channels 40 are substantially closed. Continuous lubrication passages 40, 42 are formed in the cylinder block 12 simply and economically as shown in FIG. 2, where the relative sizes of the fluid channels and the connection passages are emphasized for ease of understanding.

During operation of the hydraulic motor 10, all interconnected lubrication passages 40 are filled almost instantaneously by a minimum flow of high pressure fluid entering each cylinder 14 from the inlet 36 through the port 37. It is sent between the wall and the outer circumference of the piston 16. The loss of lubrication fluid from each lubrication channel 40 is limited by a surrounding seal 44 located near the open end of each cylinder 14. Nevertheless, the lubricating fluid in this closed continuous lubrication passage of the lubrication channel 40 responds to the pressure change in each half cycle of the piston movement and rotation of the drive shaft 30 as the piston reciprocates. Thereby continuously continuously flowing by means of a continuous minimum flow of fluid between the cylindrical wall of each cylinder and the axial cylinder of each piston. As the pressure in each cylinder 14 drops to a low pressure in accordance with the return stroke of each piston 16, the high pressure fluid in the closed lubrication passages 40, 42 causes each cylinder 14 and each piston 16 to be reduced. Flows back to the valve end of each cylinder 14 which is decompressed via again between the outer periphery of the body portion 22.

However, those skilled in the art should understand that the minimum flow of fluid returning to the cylinder 14 described above is not "loss". Instead, it immediately returns to a known hydraulic fluid closed loop interconnecting the pump and motor. In addition, since the minimum flow of such fluid does not return to the sump, there is no need to supplement the closed loop hydraulic system by the air supply pump. Finally, the closed continuous lubrication passages 40 and 42 are immediately replenished by the flow of a similar high pressure fluid from the valve end of each boosted cylinder.

As described above, the blow-by loss from the closed continuous lubrication passage 42 interconnecting all the lubrication channels 40 is minimal. That is, the flow of fluid exiting the closed continuous lubrication passage past the seal 44 at the end of each cylinder 14 can be minimized. However, this minimal blow-by is immediately replenished by the flow of similar high pressure fluid entering near the opposite end of each piston 16.

Not only is the lubrication device described above quite simple, it also simplifies the piston / swash plate interface device of the hydraulic machine, further reducing manufacturing and operating costs.

In completing the description of the hydraulic motor 10, the piston / swash plate interface device shown in FIG. 1 comprises: (a) a rotor 28 mounted on a drive shaft 30 using a conventional needle and thrust bearing, And (b) only a simple spring-tight hold-down assembly for bringing the piston shoe 24 into continuous contact with the rotating and tilting flat surface 26 of the rotor 28. [Note: Two embodiments of the simplified piston / swash plate interface assembly of the present invention are described in detail separately below.]

As shown in FIG. 1, a first embodiment of the hold-down assembly according to the invention is located about the shaft 30 and is formed appropriately around the cylinder block 12 about the axis 32. A coil spring 50 housed in a crevice 52. The spring 50 elastically supports a hold-down member 54 which is located circumferentially about the shaft 30 and the shaft 32. The hold-down member 54 is provided with a plurality of openings, each of which surrounds the neck 20 of each of the pistons 16. A special washer 56 is located between the hold-down member 54 and each piston shoe 24, respectively. Each washer 56 has an extension 58 in contact with the outer periphery of each shoe 24 such that the shoe always remains in contact with the flat surface 26 of the rotor 28.

The hydraulic motor described above, which greatly simplifies both the lubrication and the piston / swash plate interface, is efficient, easy to manufacture and economical to operate.

<Variable hydraulic pump>

3 shows a second preferred embodiment of a hydraulic machine according to the invention. The variable hydraulic pump 110 comprises a fixed cylinder block 112 of the same modularity as the cylinder block 12 of the hydraulic motor 10 shown in FIG. 1 and described above. The cylinder block 112 has a plurality of cylinders 114 (only one shown) in which a plurality of paired pistons 116 reciprocate between their retracted position and a variable forward position (maximum forward is indicated by the position of the piston 116 '). To Each piston has a spherical head 118 mounted on the neck 20 at one end of the elongated axial cylinder 122, and in a preferred embodiment the elongated cylinder 122 of each piston The length of the cylinder 114 is substantially the same. Each spherical end 118 is pivotally attached to a drive member, i.e., shaft 130, and each shoe slid across a flat surface 126 formed on the surface of the rotor 28, described in detail below. 124) fitted inside. The shaft 130 is supported by a bearing in the bore 131 at the center of the cylinder block 112.

In a manner similar to that described above with respect to the hydraulic motor 10, the variable pump 10 is also provided with a modular valve assembly 133 which is fixed by bolts as a cap on the left end of the modular cylinder block 112, Likewise, it includes a plurality of spool valves 134 (only one shown) that regulates delivery of fluid to and from the cylinder 114.

As mentioned above, the hydraulic machine operates as a pump or a motor. In this preferred embodiment, the angular variable rotating swash plate machine 110 shown in FIG. 3 is operated as a pump, and the drive shaft 130 is driven by a main drive (not shown), that is, the engine of the vehicle. Therefore, during the first half revolution of the drive shaft 130, when each piston 116 is moved to the forward position, low pressure fluid is introduced from the "closed loop" of the circulating hydraulic fluid through the inlet 136 to the port 137. And enter each cylinder (14). During the second half revolution, each piston 116 returns to the fully retracted position to direct high pressure fluid from the port 137 through the outlet 139 to the hydraulic closed loop. Then, the high pressure fluid is delivered to a paired hydraulic motor, for example, the motor 10 described above, through a suitable closed loop pipe (not shown), so that the paired piston is delivered in a known manner. Allow the volume to move at varying speeds (gallons per minute).

In other words, the modular cylinder block 112 is configured in the same manner as the cylinder block 12 described above. That is, the cylindrical wall of each cylinder 114 is traversed radially across by each lubrication channel 140 formed at its outer periphery. The plurality of passages 142 interconnect all of the lubrication channels 140 to form a continuous lubrication passage within the cylinder block 112. The cross section of the cylinder block 112 taken along the virtual plane 2-2 is the same as the cross section of the cylinder block 12 shown in FIG.

In fact, most of the above descriptions of the continuous lubrication passages 40 and 42 of the present invention relating to the apparatus of the hydraulic motor 10 shown in FIGS. 1 and 2 are the cylinders of the hydraulic pump 110 shown in FIG. 3. Each lubrication channel 140 is applied equally to the operation of successive lubrication passages 140, 142 in the block 112, and by a surrounding seal 144 located near the open end of each cylinder 114. Loss of lubricating fluid can be minimized. Likewise, the flow of lubricating fluid in the closed continuous lubrication passages 140, 142 is secondary in response to pressure changes in each half cycle of piston motion and rotation of the drive shaft 130 as the piston reciprocates. It flows continuously suitably by blow-by. Of course, as a different point in the pump 110, when each piston 116 moves to the forward position, there is a lower fluid pressure in each cylinder 114, and each piston 116 is the main drive (not shown). The high pressure fluid flows between the cylinder wall and the outer periphery of each piston 116 as it is moved from its extended position to its fully retracted position by rotation of the drive shaft 130.

However, those skilled in the art should understand that the secondary minimum fluid flow returning to the cylinder 114 described above is not "loss". Instead, it immediately returns to a known hydraulic fluid closed loop interconnecting the pump and motor. That is, since this secondary fluid flow does not return to the sump, there is no need to supplement the closed loop hydraulic system by the air supply pump. In addition, the flow of fluid exiting the closed continuous lubrication passages 140, 142 past the seal 144 at the end of each cylinder 114 can be minimized, such that a minimum blow-by It is immediately replenished by a similar minimum fluid flow entering near the opposite end of 116.

As noted above, the present invention provides for (a) the omission of a dogbone which is generally mounted between the outer end of each piston and the wobbler portion that only tilts of a conventional rotary / tilt swash plate, and (b) Figures 1 and In the embodiment shown in FIG. 3, the rotational swash plate apparatus of the machine can be simplified by omitting the wobbler portion itself and the conventional device for mounting the non-rotating wobbler to the rotating / tilting rotor of the swash plate.

With continued reference to FIG. 3, the rotor 128 of the pump 110 is pivotally mounted to the drive shaft 130 about an axis 129 perpendicular to the axis 132. Therefore, while the rotor 128 rotates with the drive shaft 130, its inclination with respect to the axis 130 may vary from 0 ° (ie, at right angles) to ± 25 °. This variable tilt is adjusted as follows. The pivot of the rotor 128 about the axis 129 is determined by the position of the sliding collar 180 which surrounds the drive shaft 130 and is movable on the axis. The adjustment link 182 connects the collar 180 to the rotor 128 with the rotor 128 such that the collar 180, which moves axially along the surface of the drive shaft 130, is the shaft 128. 129) to pivot. For example, as the collar 128 moves to the right in FIG. 3, the inclination of the rotor 128 continuously varies from + 25 ° to 0 ° (ie, at right angles) to −25 °.

The axial movement of the collar 180 is caused by the pinker 814 of the yoke 186 as the yoke 186 is rotated about the axis of the yoke shaft 190 by articulation of the yoke adjustment arm 188. Controlled by Yoke 186 is operated by a conventional linear servo mechanism (not shown) connected to the bottom of yoke arm 188. In this preferred embodiment, the rest of the yoke 186 member is housed inside the modular swash plate housing 192 and the yoke shaft 190 is supported by a bearing fixed to the housing 192, and the yoke adjustment arm 188 ) Is located outside of the housing 192.

The rotating swash plate 128 is substantially the same as the adjustment link 182 and is balanced by a shadow link 194 which is likewise connected to the collar 180 but located opposite the collar 180.

Piston shoe hold-down assembly

The pressure of the fluid continues to deflect the piston 116 in the direction of the rotor 128, and the conventional thrust plate assembly described above is provided to transfer the load. However, at operating speeds for use in motor vehicles (eg 4000 rpm), additional deflection loads are required to ensure continuous contact between the piston shoe 124 and the flat surface 126 of the rotor 128. In view of the present invention with respect to the omission of conventional dogbones, the variable hydraulic machine of the present invention provides the additional deflection load by the use of two simple elastically supported hold-down assemblies, and the two simple elastic fingers. One of the knowledge hold-down assemblies is similar to that described in connection with the hydraulic motor shown in FIG. 1.

<(a) Single spring supported hold-down assembly>

The first embodiment of the present invention for the hold-down assembly described below is a continuation of FIG. 3, but (a) is an enlarged view taken from the direction of the arrow along the imaginary plane 4A-4A of FIG. And (b) refers to FIG. 4B, which is the same as that shown in FIG. 1 and which is an enlarged view of omitted parts for clarity.

The hold-down assembly for the pump 110 is located about the shaft 130 and is housed in a suitable crevis 152 formed around the cylinder block 112 about the shaft 132 and coil coil 150. ). Coil spring 150 also elastically supports hold-down member 154 located circumferentially about shaft 130 and shaft 132. The hold-down member 154 is provided with a plurality of annular openings 160 which respectively surround the neck 120 of each piston 116. A plurality of special washers 156 are respectively located between the hold-down member 154 and each piston shoe 124. Each washer 156 has an extension 158 that contacts the outer periphery of each shoe 124 so that the shoe is always in contact with the flat surface 126 of the rotor 128.

The aforementioned positions of the components of the swash plate and the piston shoe hold-down assembly change as the inclination of the rotor 128 changes while the machine is operating. These relative changes in position can be achieved by varying the inclination of the rotor 128, i.e., + 25 ° in FIGS. 4A and 4B, + 15 ° in FIGS. 5A and 5B, 0 ° in FIGS. 6A and 6B, and in FIGS. Illustrated at 25 °. Note: One skilled in the art will have a conventional pressure balancing cavity at the center of the flat surface of the shoe 124 where each piston shoe 124 is in contact with the flat surface 126 of the rotor 128, each shoe cavity having a suitable shoe It is to be understood that the connection through the channel 162 and the piston channel 164 ensures that the fluid pressure present at the shoe / rotor interface always equals the fluid pressure at the head of each piston 116. Because the piston channel 164 passes through the center of the spherical head 118 of each piston 116, the position of the channel 164 can be used to facilitate the relative movement of the various components of the hold-down assembly. .]

Referring to the relative position of these parts at the 0 ° inclination shown in FIGS. 6A and 6B, each piston channel 164 (at the center of each spherical head 118 of each piston 116) is held- It has the same radial position with respect to each of the annular openings 160 of the down member 154. As can be seen in the figure showing the different inclinations of the swash plate 128, at all non-zero inclinations, the relative radial position of each piston channel 164 is different with respect to each opening 160, The relative position of each special washer 156 is also different.

At each of the slopes of these illustrated swash plates, the different relative positions in each of the nine openings change continuously as the rotor 128 rotates and tilts once at each of these slopes. For example, in the inclination shown in FIG. 4A, it is assumed that movement occurs only through the opening 160 at the top of the hold-down member 154 (ie, 12 o'clock) during each rotation of the rotor 128. The relative positions of the components seen in the upper openings 160 are continuously changed to correspond to the relative positions shown in each of the remaining eight openings 160.

That is, at non-zero inclinations (i.e., -25 ° shown in FIG. 7A), during each rotation of rotor 128, each special washer 156 has each shoe 124 having one side of rotor 128. As it slides over the plane 126, it simultaneously slides over the surface of the hold-down member 154, each of which has its own opening through each of the various positions seen in each of the other eight openings 160. 160). These relative motions are greatest at ± 25 °, each of which is a circulating path (remniskate) whose size varies by the inclination of the swash plate rotor 128 and the horizontal position of each of the pistons 116 of the fixed cylinder block 112. lemniscate), i.e. represent the trajectory of "number 8".

Therefore, in order to ensure proper contact between each shoe 124 and the flat surface 126 of the rotor 128, in a preferred embodiment, the size of each opening 160 is such that the boundary of the opening 160 is defined by the rotor. The relative position and opening of the special washer 156 is selected to remain in contact with at least half of the surface of each special washer 156 at all times during each rotation of 128, as shown in the figures of FIGS. 4A-7A. 160 is selected for all tilts of rotor 128 visible from each boundary.

In addition, each shoe 124 and mating special washers 156 are preferably manufactured using a reinforced thermoplastic resin material. These mating parts are also combined to form one thermoplastic shoe / washer combination, the shoe portion being made to be formed about the spherical head 118 of each piston 16 ′, 22. Likewise, the use of reinforced thermoplastics can significantly reduce the cost and complexity of the thrust bearing assembly 35.

<(b) Multi-Spring Supported Hold-Down Assembly>

The second embodiment of the present invention with respect to the hold-down assembly is slightly more difficult to assemble, but is quite simple and inexpensive. This second embodiment is shown in FIG. 8 in a sectional view, partially enlarged, of a single piston of another hydraulic machine 210 according to the present invention. The piston 216 is located as a modular cylinder block 212 fixed inside the cylinder 214. The cylinder 214 is traversed radially across each lubrication channel 40 "formed on the outer periphery. In the same manner as described with respect to the other hydraulic machines described above, the lubrication channel 40" is a plurality of passages. Are interconnected with similar channels of other cylinders to form a continuous lubrication passage within cylinder block 212. Similarly, a surround seal 244 is positioned near the open end of each cylinder 214 to minimize the loss of lubrication fluid from each lubrication channel 40 ".

The difference between the fixed cylinder block 212 and the modular cylinder block shown in FIGS. 1 and 3 is that only the fixed cylinder block 212 has a large axial cylindrical coil spring or an axial direction for holding the coil spring. It does not contain columnar crevis.

Although not shown, the fixed modular cylinder block 212 of the hydraulic machine 210 may be connected to a fixed angle modular swash plate assembly (FIG. 1) or a variable angle modular swash plate assembly (FIG. 3), but in any case Edo hydraulic machine 210 further simplifies the hold-down assembly. In particular, the hold-down assembly of this embodiment includes only each conventional piston shoe 224 for each piston 216 that is only combined with each coil spring 250. Each coil spring 250 is also associated with a respective piston 216.

Each piston shoe 224 is similar to the conventional shoe shown in the first hold-down assembly described above, and likewise mounted on the spherical head 218 of the piston 216 to rotate the swash plate of the machine in a similar manner as described above. Slide over flat surface 226 formed on the surface of rotor 228. Each coil spring 250 is respectively disposed about the hydraulic valve port 237 at the valve end of each cylinder 214 and is positioned within the body portion of each piston 216, respectively.

In the manner described above, each shoe 224 is pieced of the rotor 228 by a remniscate operation that varies the magnitude of the horizontal position of each piston 216 and the tilt of the rotor 228 relative to the axis 230. Slip over plane 226. While the hydraulic machine 210 is operating normally, the shoe 224 maintains contact with the flat surface 226 of the swash plate by the fluid pressure. Therefore, the spring bias provided by the coil spring 250 is minimized but sliding contact between each shoe 224 and the flat surface 226 in the absence of fluid pressure at the valve end of each cylinder 214. It is still enough to stay effective.

The minimum bias 250 of the spring described above not only facilitates assembly but also is sufficient to prevent the inclusion of fine dust and metal fragments generated during assembly or by abrasion. It should also be understood that this second embodiment provides the necessary functionality with only very low cost components.

Both the aforementioned pumps / motors and other hydraulic machines of the present invention are more economical by reducing the number of parts required for effective operation and increased volumetric efficiency, since the lubrication and piston / swash plate interfaces are quite simple and the manufacturing costs are relatively low. to be.

Claims (19)

A plurality of pistons formed in the cylinder block and reciprocally mounted to each of the cylinders located on the circumference of the first radial distance about the axis of rotation of the drive member, each of the pistons having an axial cylindrical portion and a head end; Each cylinder has a valve end and an open head portion, the head end of each piston is always advanced past the open head portion, and the piston also has a predetermined maximum stroke for the passage of pressurized fluid. Hydraulic machine with variable stroke up to Further comprising respective lubrication channels formed in the cylindrical wall of each cylinder in said cylinder block to maintain said pressurized fluid, The lubrication channels are all interconnected to form a continuous lubrication passage within the cylinder block, The pressurized fluid is maintained in the continuous lubrication passage by substantially closing each of the lubrication channels by the outer surface of the axial cylinder of the respective piston during the complete stroke of the respective piston, Only the pressurized fluid received by the lubrication passage is the minimum flow of the fluid between the cylindrical wall of each cylinder and the axial cylinder of each piston, The closed and continuous lubrication passage is formed entirely within the cylinder block, transecting across each of the cylinders, and substantially equal radial distances such that the cylinder is disposed about an axis of rotation of the drive member. Located on the circumference of the Hydraulic machine, characterized in that. The method of claim 1, And further comprising a sealing member positioned near the head portion of each cylinder to substantially remove blow-by between each piston and the head portion of each cylinder. . The method of claim 1, A gap between the cylindrical portion of each piston and the respective cylinder, wherein the gap is selected to ensure the minimum flow between the cylindrical wall of each cylinder and the axial cylinder of each piston Is sufficient to cause movement of the lubricating fluid in the closed continuous lubrication passage by at least one of (a) piston action, and (b) fluid pressure change at the valve end of each cylinder. Hydraulic machinery. The method of claim 1, A second hydraulic machine is further included, wherein the second hydraulic machine is of the same type as the hydraulic machine, and the hydraulic machine and the second hydraulic machine are connected to each other in the form of a conventional closed loop of circulating hydraulic fluid. The high pressure fluid exiting the hydraulic machine is directly delivered to the second hydraulic machine, and the low pressure fluid exiting the second hydraulic machine is directly transmitted to the inlet of the hydraulic machine, and the hydraulic machine and the second hydraulic machine are The minimum flow of fluid in the closed continuous lubrication passage between the respective piston of all the machines and the valve end of the respective cylinder is immediately returned to the closed loop of the circulating hydraulic fluid without the use of an air supply pump. Hydraulic machine, characterized in that. The method of claim 1, And a swash-plate having a flat surface, wherein the swash plate has an inclination with respect to the axis of rotation of the drive member, the head end of each piston having all relatives between the piston and the swash plate. Maintains an effective sliding contact with the flat surface of the rotating swash plate during the rotational operation, the stroke of the piston being determined by the inclination of the rotating swash plate, and the cylindrical portion of each piston continues with the flat surface during the stroke. And a long axial cylinder length sufficient to be supported inside each cylinder to minimize lateral displacement of the head end of the piston in the case of relative sliding contact. The method of claim 5, The cylinder block is fixed in the housing, the swash plate is rotated by the drive member, and includes a rotor that rotates and tilts, the flat surface being located on the rotor. The method of claim 5, The cylinder block is fixed in the housing, the rotating swash plate is designed to include a rotating and tilting rotor and a tilting wobbler, the flat surface being located on the wobbler. The method of claim 7, wherein The inclination of the rotating swash plate is variable, the hydraulic stroke of the piston is changed to a predetermined maximum value in accordance with the inclination. The method of claim 5, The piston has a spherical head end connected to the piston body by a narrowed neck portion, Each sliding shoe pivotally attached to the spherical head end of each piston and maintaining effective sliding contact with the flat surface of the swash plate continuously during the relative rotational operation between the piston and the flat surface, and Hold-down assembly for biasing the sliding shoe toward the flat surface of the rotating swash plate Hydraulic machine comprising a further. The method of claim 9, The hold-down assembly is A hold-down member having a plurality of openings, the boundary of each of the plurality of openings being located near a narrowed neck portion of each piston, and A washer fitted about a narrowed neck portion of each piston between the hold-down member and each sliding shoe, each having a cylindrically aligned extension such that each of the sliding shoes is in contact with the circumference thereof Including, The washer is in sliding contact with the hold-down plate to move relative to the hold-down plate in response to a change in relative position of the sliding shoe when the flat surface of the rotor is inclined with respect to the axis of rotation of the drive member. Doing Hydraulic machine, characterized in that. The method of claim 10, The boundary of each opening of the hold-down plate is designed to be always in contact with at least half of the outer circumference of the respective washer during the relative movement. The method of claim 10, And a minimum spring bias sufficient to maintain an effective sliding contact between the shoe and the flat surface of the swash plate in the absence of fluid pressure at the valve end of each cylinder. The method of claim 12, The minimum spring bias is provided by a coil spring located circumferentially at a distance less than a first radial distance to bias the hold-down plate relative to the washer about the axis of rotation of the drive member. Hydraulic machine. The method of claim 12, The minimum spring bias is provided by a plurality of coil springs, each coil spring being located between the hold-down plate and one of the washers. The method of claim 9, The hold-down assembly is Only a minimum spring bias sufficient to maintain an effective sliding contact between the shoe and the flat surface of the swash plate in the absence of fluid pressure at the valve end of each cylinder, The minimum spring bias is provided by a plurality of springs respectively positioned between the cylindrical portion of each piston and the valve end of each cylinder. A plurality of pistons formed in the cylinder block and reciprocally mounted to each of the cylinders located on the circumference of the first radial distance about the axis of rotation of the drive member, each of which is defined by a piston body and a narrowed neck portion; Has a spherical head end connected to the piston body portion, each cylinder having a valve end and an open head portion, and the head end of each piston is always advanced past the open head portion, It has a rotating swash plate having a flat surface, the rotating swash plate has an inclination with respect to the axis of rotation of the drive member, The head end of each piston maintains an effective sliding contact with the flat surface of the rotating swash plate during all relative rotational operations between the piston and the rotating swash plate, the stroke of the piston being determined according to the inclination of the rotating swash plate, The piston is also a hydraulic machine that varies up to a predetermined maximum stroke for the passage of pressurized fluid, Each sliding shoe pivotally attached to the spherical head end of each piston and positioned to slide in contact with the flat surface of the swash plate; A hold-down member biased toward the sliding shoe and having a plurality of openings, one of which is located near the narrowed neck portion of each piston, and A respective washer having an extension between the hold-down plate and each sliding shoe, the extension of which is fitted around the narrow neck portion of each piston and aligned to contact each sliding shoe Including, The washer is in sliding contact with the hold-down plate to move relative to the hold-down plate in response to a change in relative position of the sliding shoe when the flat surface of the rotor is inclined with respect to the axis of rotation of the drive member. Done Hydraulic machine, characterized in that. The method of claim 16, Wherein each washer extension is cylindrically aligned to circumferentially contact with the respective sliding shoe. The method of claim 16, The boundary of each opening of the hold-down plate is designed to always be in contact with at least half the outer circumference of each of the washers during the relative movement. The method of claim 16, And a coil spring circumferentially positioned at a distance less than a first radial distance to deflect the hold-down plate relative to the washer about the axis of rotation of the drive member.

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