Transmission device for continuous alteration of the revolutions

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous variable speed transmission device having a V-belt connecting a primary and a secondary pulley, each of which comprises two conical discs, i.e. one fixed disc coupled to the primary or secondary shaft and a second movable disc mounted a primary or optional secondary shaft and configured as an adjustable piston of a hydraulic cylinder, the transmission device comprising a pump for the hydraulic medium.

In known transmission devices of this kind, the internal spaces of the hydraulic cylinders are connected to the pump by a hydraulic system which comprises a control hydraulic unit composed of a double-sided piston in a cylinder which is connected to the pump on one side and the pulley and the second pipe is connected to the roller of the movable disk of the secondary pulley. Depending on the position of the double-sided piston in the cylinder, the transmission ratio is set by this hydraulic unit.

Since only the transmission ratio is adjustable in these known devices, these devices are not suitable for use in many areas, for example, for vehicles powered by internal combustion engines, in which much more demanding requirements are imposed on the transmission control. This is in particular a requirement for adjusting the tension of the drive belt as a function of the load on the gear, i.e. that the tensioning force is always optimal and always adapts itself to frequent and rapid changes in the primary speed and the associated transmitted torque.

The purpose of the invention is to overcome the drawbacks of the known transmission devices and to enable their use in several fields, in particular for vehicles powered by internal combustion engines.

This is achieved in a transmission device according to the invention, characterized in that a first control valve for adjusting the pressure of the hydraulic medium in said cylindrical space is connected to the first pipe connecting the pump to the cylindrical space of the movable disk of the secondary pulley. a second conduit having a cylindrical space of the movable disk of the primary pulley, resulting in a discharge conduit from the second control valve. The first control valve, which preferably comprises an overflow valve, is provided with a first-line pressure adjusting piston and a biased compression spring disposed between the piston and a slidably supported backing plate rigidly coupled to a sensing member supported on the movable disk flange of the secondary pulley.

In the preferred embodiment, both the first control valve and the second control valve are connected to their control spaces above the piston of the pitot tube, which in a flange connected to the primary shaft is inserted into an annular groove which is open radially towards the shaft axis.

While the second control valve adjusts the fluid pressure for adjusting the transmission ratio in the device according to the invention, the first control valve adjusts the fluid pressure and hence the drive belt tension depending on the set transmission ratio. Separation of the belt tension control from the gear ratio control makes it possible to maintain optimal operating conditions in the transmission device.

A further enhancement of the effect of the invention is achieved in a gearbox driven by an internal combustion engine in which the piston of the second control valve is supported by a biased compression spring in the space below the piston, the other end of which is in contact with a slidingly supported support plate closing the chamber of the body, which is connected to the inlet pipe of the internal combustion engine through a gas pipe, wherein a shut-off valve is provided in the gas line for shutting off the gas supply when the pressure in the internal combustion engine drops.

The object of the invention is evident from the description and drawing, in which the apparatus according to the invention in an exemplary embodiment is schematically illustrated.

According to the illustration, the transmission device is provided with a primary V-belt pulley 1 and a secondary V-belt pulley 2. These pulleys 1, 2 consist of two, axially displaceable conical discs. The primary pulley 1 consists of a fixed conical disk J which is mounted on the primary shaft J and a movable conical disk 6 which is axially displaceably mounted on the primary shaft X and against. rotation with respect to the shaft X is ensured, for example, by keyways. Similarly, the fixed conical disk 2 of the secondary pulley 2 is mounted on the secondary shaft 8 and the movable conical disk 6 is axially displaceably mounted on the secondary shaft 8. Drive pulley 2 circulates on both pulleys 1, 2 ·

The primary shaft X can be driven by an internal combustion engine and drives the secondary shaft 6 at an adjustable rotation speed via a belt 2. This speed is dependent on the distance between the conical discs i. and £ primary pulley 1 and conical disk 2 and £ secondary pulley 2 ·

The setting of pulleys 1 and 2 corresponds to the large gear ratio as shown. that the input speed is much greater than the output speed. The axial distance between the conical discs 2 and A of the primary pulley 2 is substantially greater than the axial distance between the conical discs 2 and 4 of the secondary pulley 2.

The movable discs 1 and 6 are displaceably mounted on the shafts X and are operated hydraulically. For this purpose, the movable disk 6 of the primary pulley is designed as a. the piston of the cylinder 32 mounted on the primary shaft χ. The inner space 11 of the cylinder 10 thus formed is filled with hydraulic fluid which can be supplied or discharged via a channel 12 in the primary shaft X and a line 13 connected to this channel 22. The axially movable conical disk 2 of the secondary pulley 2 together with the sleeve mounted on the secondary shaft 8, the hydraulic cylinder 52 forms a fluid into the space 15 of the cylinder 15 through a line 16. By the pressure of the liquid, the movable disc 6 moves to the fixed disc 2 and, as a result, the conical discs 2 & gt; • This clamping force results in the tension in the drive belt 2 required for torque transmission.

To adjust the pressure of the liquid in the chamber 1X of the cylinder 15, the device is provided with a first control valve 12 which, as a transfer valve, effectively limits the pressure. of the liquid conveyed from the tank 21 by the pump 52 through the filter 22. As a result, a continuously adjusted liquid pressure is applied in the line 16. The first regulating valve 18 is provided with a piston 22 with recesses 21 which, when the piston 22 is open, to the right, as shown in the figure, create a passage for liquid from the pipe 24 to the discharge pipe 24.

In the discharge line 24, a lower fluid pressure is maintained by means of a spring-loaded check valve 25, so that the fluid required to lubricate the drive belt 2 can be supplied to line 2 by means of line 26, 22 and via line 30 to tank 21 and line 31 to convey liquid to the annular groove 22. formed in a flange connected to the primary shaft X and open radially toward the axis of the shaft X.

During rotation of the primary pulley 1 and thus of the flange with the annular groove 32, the liquid present in the groove 32 will rotate. ^ve which fluid pressure is dependent on the speed of the primary pulley 1. Through lines 34 and 35, this pressure acts in the space 36 of the first control valve. the pressure of the liquid in the space 36 and consequently the piston 22 moves to the right, causing a decrease in the pressure of the liquid in the conduit.

^Nand ^MrsWed 22 ^paobí na^pro^{ti t}omu direction ^dO^leva na^pchildren ^pru^žny ³7. influenced by^pa sensing plate 18 which is axially displaced by the rod 32 as a function of the axial displacement of the movable disk 6 of the secondary pulley 2;

40. supported on the flange £ 1 of the movable disk g of the secondary pulley 2, the sensing member | 0 is pressed against the flange £ inou by a spring y. The force that acts on the piston 22 to the left is.

decreases when the disc 6 moves to the right, i.e. when the relative distance of the conical discs,, sekund of the secondary pulley £ increases. This relative distance and, consequently, the position of the backing plate gives an instantaneous transmission ratio. At a large transmission ratio, the backing plate ££ is shifted to the left, while at a small transmission ratio it is shifted to the right, thereby reducing the spring preload XL. . As a result, the force exerted by the conical discs £, £, the secondary pulleys i to the drive belt 2 is reduced.

As already mentioned, the clamping force exerted by the conical wheels 6, 2 of the secondary pulley g on the drive belt 2 is dependent on the primary speed and the transmission ratio. The clamping force increases as the primary speed decreases and the transmission ratio increases.

The transmission ratio is regulated by the inlet and outlet of fluid from the space 11 of the roller 10 of the primary pulley. When the liquid is fed into the cylinder compartment 11, the movable disk 6 forming the piston moves towards the fixed disk J under sufficient pressure, thereby increasing the running diameter of the drive belt 2 on the primary pulley 1.^E the invariant distances between the primary shaft 2 in the secondary shaft 6 and the drive belt 2 push the conical disks 6 and 6 of the secondary pulley 6 apart, of course, while maintaining the clamping force between the disks 6, 7 which is adjusted by the first control valve 18. ratio.

The chamber 10 of the cylinder 10 is supplied with fluid from the pipe 8, which has the pressure set by the first control valve 18. Since this fluid pressure has to exert a greater force on the movable disk 8 than on the movable disk 8, it must have a primary hydraulic and a cylinder 10 having a larger effective area than the secondary hydraulic unit.

The inlet and outlet of the fluid from the cylinder chamber is controlled by a second control valve 42 provided with a piston. The piston 43 is applied to the right by the pressure of the liquid in the space 54 and to the left by the tension of the spring 54, thereby keeping the piston 43 in equilibrium. In this equilibrium position, the liquid is either fed through line 46 through chamber 52, line 81 and channel to chamber 11 of cylinder 52, or is discharged through channel 12 through line 11, chamber 8, and line 52 to tank 21. alternatively, a constant amount of liquid is maintained in the cylinder chamber.

The pressure of the liquid in the space 44 corresponds to the pressure measured by the pitot tube 48 which acts through the conduit 34 in the space 44. Increasing the pressure in the space 40 due to the increase in the primary speed causes the equilibrium position of the piston 43 to be shifted to the right. As a result, the liquid supply and / or the restriction of the liquid removal from the cylinder space 60 of the cylinder 6 is respectively. The supply of liquid to the space 10 of the cylinder 10 results in a reduction of the transmission ratio. Therefore, an increase in the primary speed results in a reduction in the transmission ratio.

The spring 45 is preloaded by the support plate £ 2 connected to the membrane £ 2 » ^forDepending on the gas pressure difference on both sides of the diaphragm 50, the bias of the spring 60 may be controlled. The body £ 2 of the membrane £ 2 is divided into two spaces by the membrane £ 2. The space 55 is connected to the environment through the opening 54, and the chamber space 54 in which the spring 54 is located, is connected, for example, by gas line 52, shut-off valve 52 and gas line 59 to the inlet connection of an internal combustion engine. equipment. With valve 58 open, i.e. in the position shown in the drawing, the chamber 54 exerts the same pressure as in the inlet nozzle of the internal combustion engine, resulting in a certain position of the diaphragm 52. If the pressure in the inlet nozzle increases when the gas is added, i.e. the diaphragm 52 moves to the left, which results in an increase in the force exerted to the left on the piston 43. As a result, the increased liquid drain or the liquid supply to the cylinder space 54 of the cylinder 54 is reduced. the tendency to increase the transmission ratio.

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The diaphragm 50 is provided with a stop 52 which limits its movement to the right. This ensures that further reducing the pressure in the inlet pipe of the internal combustion engine below a predetermined value does no longer affect the transmission.

If the transmission device is mounted in a vehicle and driven by an internal combustion engine, the shut-off valve 58 serves as a so-called mountain brake. When the vehicle is braked by the engine, a very low pressure is generated in the inlet sleeve, while a relatively small gear ratio is still required. The valve 58 is provided with a plug 63 which is held in the open position by the spring 64, whereby the gas lines 57 and 59 are connected together. The electric winding 65, which pushes the core 66, is energized by the switch 63. hence the plug 63 against the action of the spring 64, thereby closing the mouth 67 of the conduit. As a result, the gas conduit 59 is connected via the space 60 to the gas conduit 57. The diaphragm 68 separates the space 62 from the space 69 under atmospheric pressure. The diaphragm 68 is forced by the spring 61 from the second orifice 70 of the conduit 22.

With the mountain brake applied, i.e. with the mouth 67 closed, the pressure in the space 62 decreases at a low pressure in the line 59 so that the diaphragm 68 is pushed against the action of the spring 61 so that the mouth 70 closes with the membrane 68. thus, the gas pressure drop in the chamber 54 is reduced. Thus, the transmission ratio of the transmission does not increase too much.

If a clutch, such as a centrifugal clutch or a fluid clutch, is fitted between the transmission and the drive motor, it may be desirable that the transmission be brought to a standstill when the clutch is disengaged, for example to change the direction of rotation of the secondary shaft 8 to reverse. mounted on the secondary shaft £. To stop the transmission, the line 71 is connected via a valve 72 and the line 23 to the brake cylinder 74. By moving the control rod 75 with the cam 76, the valve rod 77 is moved axially with the thumb 76 following the surface of the cam 76. As a result, the fluid from the line 16 can come into contact with the brake cylinder 74. ⁱⁿ wherein a pressure can be exerted which causes the brake block 22 »which forms the piston in the brake cylinder 21» against the brake surface 80 of the fixed conical disk Д of the primary pulley 1 at a predetermined travel length of the control rod 75 which the transfer stops.

If the transmission device is used in a vehicle, the preload of the spring 45 may also be adjustable depending on the position of the gas control lever in the vehicle by mechanically connecting the gas lever to the support plate 52.