JP2006002912A - Hydraulic controller of toroidal transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the hydraulic controller of a toroidal transmission mechanism that can control a difference of a pressure control characteristic between the elongation side and the shortening side of the variator roller drive cylinder by the pressure setting accuracy of a control valve bearing to small with simple design about the transmission control characteristic of the speed change gear of a toroidal transmission mechanism. <P>SOLUTION: The hydraulic controller of the toroidal transmission mechanism connects the variator roller 44 for transmitting a step-less speed change with the elongation side and the shortening side of the double acting cylinder 44a that drives advance or retreat and its elongation side and shortening side are composed of two hydraulic controller to control each active hydraulic pressure. These two hydraulic controllers are consisting of a proportional solenoid pressure reducing valve 53 to adjust the hydraulic pressure according to an input signal and a variable reduce valve 54 capable of adjusting the active hydraulic pressure by receiving its output pressure as the pilot pressure, and the adjustable pre-load pressure set part 54a, 54s about the pilot pressure are established with this variable reduce valve 54. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic control device for a toroidal transmission mechanism used in a work vehicle.

  As shown in Patent Document 1, a hydraulic control device for a transmission device of a toroidal transmission mechanism is known. As shown in FIG. 2 of the same document, this hydraulic control device is provided with an oil pump for each of the extension side and the shortening side of the cylinder for driving the variator roller forward and backward, and the holding pressure of the hydraulic oil supplied by this oil pump is set. An electric hydraulic proportional pressure control valve is provided for adjustment. By sending a signal to this electrohydraulic proportional pressure control valve, the variator roller position is adjusted to advance and retreat, and the inclination angle is changed, so that the speed ratio of the variator can be adjusted steplessly.

However, the advance / retreat operation of the variator roller by the hydraulic control device is affected by variations in the pressure control characteristics on the pressure setting accuracy of the control valve, so that it is possible to avoid the difference between the transmission control characteristics on the expansion side and the shortening side. became.
Japanese Patent Application Laid-Open No. 2002-227953

  The problem to be solved is that the transmission control characteristic of the transmission of the toroidal transmission mechanism is reduced by a simple configuration to reduce the difference between the pressure control characteristics of the variator roller drive cylinder due to the pressure setting accuracy of the control valve. An object of the present invention is to provide a hydraulic control device for a toroidal transmission mechanism.

According to the first aspect of the present invention, the variator roller 44 for continuously variable transmission is connected to the extending side and the shortening side of the double acting cylinder 44a for advancing and retracting, and the working hydraulic pressures S1 and S2 on the extending side and the shortening side are respectively connected. In the hydraulic control device for a toroidal transmission mechanism including two hydraulic control units to be controlled, the two hydraulic control units each have an electromagnetic proportional pressure reducing valve 53 that adjusts the hydraulic pressure in accordance with an input current signal, and pilots its output pressure. The variable reduce valve 54 is capable of adjusting the working oil pressure by receiving the pressure as a pressure, and the variable reduce valve 54 is provided with pressure setting portions 54a and 54s capable of adjusting the preload with respect to the pilot pressure. .
The electromagnetic proportional pressure reducing valve causes the pilot pressure corresponding to the input current signal to act on the variable reduce valve, and the variator roller is driven back and forth by the pressure control of the amplification characteristic adjusted by the pressure setting portion on each of the expansion side and the shortening side. .

In the invention according to claim 2, the variator roller 44 for continuously variable transmission is connected to the extending side and the shortening side of the double-acting cylinder 44a that drives forward and backward, and the working hydraulic pressures S1 and S2 on the extending side and the shortening side are respectively connected. In the hydraulic control device for a toroidal transmission mechanism including two hydraulic control units to be controlled, the two hydraulic control units each have an electromagnetic proportional pressure reducing valve 53 that adjusts the hydraulic pressure in accordance with an input current signal, and pilots its output pressure. The variable relief valve 59 is a variable relief valve 59 capable of adjusting the holding oil pressure as a pressure. The variable relief valve 59 is provided with a pressure setting portion 59a capable of adjusting the preload with respect to the pilot pressure.
The electromagnetic proportional pressure reducing valve causes the pilot pressure corresponding to the input current signal to act on the variable reduce valve, and the variator roller is driven back and forth by the pressure control of the amplification characteristic adjusted by the pressure setting portion on each of the expansion side and the shortening side. .

The hydraulic control device for a toroidal transmission mechanism of the present invention has the following effects.
The effect of the invention according to claim 1 is that the pilot pressure corresponding to the input current signal acts on the variable reduce valve by the electromagnetic proportional pressure reducing valve, and the variator roller is moved forward and backward by pressure control of the amplification characteristics on the expansion side and the shortening side. Since it is driven, it is possible to improve the transmission control accuracy of the variator roller by sharing the pressure control characteristics of the extension side and the shortening side by adjusting the amplification characteristics.

  The effect of the invention according to claim 2 is that the pilot pressure according to the input current signal is applied to the variable relief valve by the electromagnetic proportional pressure reducing valve, and the variator roller is moved forward and backward by pressure control of the amplification characteristics on the expansion side and the shortening side. Since it is driven, it is possible to improve the transmission control accuracy of the variator roller by sharing the pressure control characteristics of the extension side and the shortening side by adjusting the amplification characteristics.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view of an agricultural tractor showing an example of a work vehicle equipped with a toroidal transmission to which a hydraulic control device according to the present invention is applied. This agricultural tractor has an engine c mounted on the front part of the machine body having a front wheel a and a rear wheel b, transmits the rotational power of the engine c to the transmission 1, and the power decelerated appropriately by the transmission 1. While transmitting to the front wheel a and the rear wheel b, it is comprised so that it may output to the working machine K1 via the PTO shaft k of the rear part. Further, for operation by the operator, a monitor m for displaying a driving state in front of the steering wheel h, an accelerator pedal p below, and a shift lever 7 etc. disposed on the side of the cockpit q provided on the upper part of the transmission 1 are arranged. The control unit C is configured to be capable of automatic shifting.

  In the transmission 1, a traveling transmission system using a toroidal transmission mechanism is installed in addition to the transmission system of the PTO shaft k. As shown in a side view of the main part of FIG. 2, this toroidal transmission mechanism has a transmission unit 21 using a full toroidal variator, a partition wall 9 for a traveling transmission shaft 5 that receives power from the shaft end (right end in the figure) side. A planetary mechanism 22 following the rear side, a high / low switching portion 23 composed of two clutches Hi and Lo, etc. are configured on the axis of the traveling transmission shaft 5, and a predetermined section defined by the partition wall 9 in the transmission case Place in.

  The variator 21 includes two input disks 41 and 42 arranged in the front-rear direction, an output disk 43 arranged therebetween, and an opposing surface formed in an annular concave shape. It is constituted by three front and rear variator rollers 44 interposed at a circumferential interval. The input disk 41 on the front side is pivotally supported by the traveling transmission shaft 5 while receiving the hydraulic pressure of the end load acting in the axial direction by the internal piston, and the output disk 43 has a sleeve-like transmission member 45 extending rearward. It is attached and pivotally supported on the traveling transmission shaft 5, and the rear input disk 42 is pivotally supported on the transmission member 45, so that the continuously variable transmission power corresponding to the inclination of the variator roller 44. Output. The variator rollers 44... Ensure transmission by receiving dedicated hydraulic oil, and perform an infinitely variable transmission by adjusting an inclination angle by a hydraulic system that controls the advance / retreat position.

  As shown in the system diagram of FIG. 3, the hydraulic control system of the variator 21 includes double-acting hydraulic cylinders 44a for moving the variator rollers 44 forward and backward, and is formed in each cylinder rod 44b. The dedicated hydraulic oil is supplied through the oil passage, and lubrication and cooling are performed while ensuring the transmission between the input disks 41 and 42 and the output disk 43, and the variator rollers 44 are driven forward and backward by the hydraulic cylinders 44a. The end load pressure by the shaft end input of the traveling transmission shaft 5 is controlled.

  More specifically, the hydraulic cylinders 44a of the variator rollers 44 are provided with two hydraulic control units for expansion and contraction that are hydraulically connected in parallel and control the working hydraulic pressure on the expansion side and the contraction side, respectively. To do. These two hydraulic pressure control units receive a predetermined supply pressure from the pump P by the reduce valve 52, and act as electromagnetic pilot pressure reducing valves 53, 53 for adjusting the hydraulic pressure according to the input current signal, and the output pressure as a pilot pressure. The variable reduction valves 54 and 54 capable of adjusting the hydraulic pressure are used. The drain side hydraulic oil is supplied from the cylinder rods 44b to the rolling surfaces of the variator rollers 44. Pressure setting portions including springs 54s and 54s and adjusting screws 54a and 54a are attached to the pilot ports of the variable reduce valves 54 and 54, respectively.

  Further, a shuttle valve 55 is interposed between the oil passages on the extending side and the shortening side of the hydraulic cylinders 44a, so that the higher one of the control pressures S1 and S2 is used as a pilot pressure by the shuttle valve 55. The end load is controlled by the valve 56 in response to the speed change caused by the tilting operation of the variator rollers 44 to adjust the rolling contact pressure of the variator rollers 44. These dedicated hydraulic oils are circulated and used only within a predetermined section.

  The valves other than the shuttle valve 55 are configured as a valve block 57 including the main relief R as shown in the development view of the valve block configuration example of FIG. The two variable reduce valves 54 and 54 communicate with the pilot pistons 54p and 54p in correspondence with the outputs of the electromagnetic proportional pressure reducing valves 53 and 53, respectively, and by pressure adjusting springs 54s and 54s and adjusting screws 54a and 54a. The pressure setting part is configured in the base part of the valve block 57.

  The hydraulic pressure control device configured as described above controls the input current signal of the electromagnetic proportional pressure reducing valve 53 corresponding to the speed change lever, so that the pilot pressure corresponding to the forward / backward turning operation of the speed change lever acts on the variable reduce valve 54. The variator rollers 44 are driven forward and backward by pressure control of the amplification characteristics on the extension side and the shortening side. For example, as shown in the pressure control characteristic diagram showing an example of the amplification characteristic in FIG. 5, the electromagnetic proportional pressure reducing valve 53 for 25 kilogram weight / square centimeter (hereinafter referred to as “kgf / cm 2”) is variable for 50 kgf / cm 2. The amplification characteristic of the reduce valve 54 can be obtained.

  In this case, by adjusting the pressure setting unit 54a with respect to the control characteristic C1 of the electromagnetic proportional pressure reducing valve 53, even if there are characteristic variation widths C1L to C1U due to pressure accuracy, the common control characteristic on the expansion side and the shortening side C2 can be aligned. Therefore, by sharing the pressure control characteristics on the extension side and the shortening side by adjusting the amplification characteristics, the transmission control accuracy of the variator 21 can be improved through the control of the variator rollers 44.

Next, another hydraulic control system of the variator 21 will be described. In the following description, the same members as those described above are denoted by the same reference numerals, and description thereof is omitted.
In this hydraulic control system, as shown in the system diagram of FIG. 6, a predetermined supply pressure is supplied from the pump P to the hydraulic cylinders 44a of the variator rollers 44 through the reducing valve 52, and hydraulic oil for extending and shortening is supplied to the hydraulic cylinders 44a. Two hydraulic pressure control units that receive and control the holding pressure are provided. These two hydraulic pressure control units are composed of electromagnetic proportional pressure reducing valves 53 and 53 that adjust the hydraulic pressure in accordance with an input current signal, and variable relief valves 59 and 59 that can adjust the holding hydraulic pressure using the output pressure as a pilot pressure. To do. The pilot pressures of these variable relief valves 59 and 59 are each provided with a pressure setting portion by an adjusting screw 59a acting on the spring pull 59s. The cylinder rods 44b of the variator rollers 44 and the pressure control valve 56 for end load control are connected to the supply hydraulic pressure.

  These valves are configured as a valve block 60 including the main relief R, as shown in the development example of the configuration example of FIG. The two variable relief valves 59 and 59 communicate with the outputs of the electromagnetic proportional pressure reducing valves 53 and 53 corresponding to the pilot pressures, and screw the adjustment screws 59a and 59a for adjusting the set pressure of the springs 59s and 59s. A holder is formed on the base of the valve block 60.

  By adjusting the amplification characteristics of the two variable relief valves 59, 59 on the expansion side and the shortening side by the pressure setting portions 59a, 59a by the hydraulic control device having the above-described configuration, the expansion side and the shortening side are similarly controlled. Control characteristics can be aligned.

  The roller lubrication circuit of the variator 21 supplies hydraulic oil from the T port of the main relief R to the cylinder rods 44b of the variator rollers 44 as shown in the hydraulic system diagram of FIG. As a result, the unnecessary total flow rate of the main relief R can be routed to lubricate a large number of variator rollers 44..., So that a larger number of variator rollers can be used compared to the case where a constant flow rate is supplied from the secondary pressure circuit through the orifice. The durability of the variator roller can be reduced at a low cost while keeping the pump capacity small and minimizing engine horsepower loss without incurring a situation where the amount of lubricating oil for 44 ... is insufficient and the required constant pressure cannot be maintained. Can be secured.

  As for the lubrication circuit for gears and bearings of the variator 21, as shown in the hydraulic system diagram of FIG. 9, lubrication is performed from the drain ports of the electromagnetic proportional pressure reducing valves 53 and 53 and the pressure reducing valves 54 and 54 through the traveling transmission shaft 5. Configure to supply oil. This makes it possible to lubricate and cool the variator rollers 44 under transmission conditions not immersed in oil, and to ensure durability.

  As another example of lubrication of the variator rollers 44, lubricating oil (cooling oil) of the variator rollers 44 is supplied from the drain port of the pilot relief valve R as shown in the hydraulic system diagram of FIG. As a result, the unnecessary total flow rate (basically, the total flow rate of the pump except when the cylinder is in operation) can be turned to lubricate a large number of variator rollers 44... Compared with the case of supplying oil, it is necessary to have multiple pumps for securing the oil amount or a large capacity pump combined with a diverter valve in order to compensate for the shortage of lubricating oil amount (it is difficult to maintain a constant pressure if it increases). In addition, the durability of the variator roller can be ensured at a low cost while minimizing the engine horsepower loss by reducing the pump capacity.

  In this case, the lubrication circuit of the variator rollers 44 is further supplied from the drain ports of the variable reduce valves 54, 54, so that the variator rollers 44, such as forward / backward movement of the fuselage, are particularly activated (working cylinder). When the pressures S1 and S2 are switched), the flow rate is taken by the cylinder operation, and the lubricating oil (cooling oil) of the variator roller 44 is momentarily insufficient but the durability of the variator roller 44 is impaired. Can be solved.

  The end load of the variator 21 directly supplies the higher one of the cylinder operating pressures S1, S2 of the variator rollers 44 through the shuttle valve 55, and constitutes a pilot relief R using this operating pressure as a pilot pressure. R is configured such that it can be set to a low pressure of about 5 to 10 kgf / cm 2 at the initial stage (when there is no end load pressure). Specifically, as shown in FIG. 11, a developed sectional view of the valve block 61 is shown in FIG. 11. The pilot relief R includes a relief poppet and a pilot pressure receiving portion as an integral member R1, and a spring R2 that sets a minimum pressure. A set part is constituted by the adjusting screw R3.

  The pilot relief R having the above configuration receives hydraulic oil from the P port, receives the end load of the E port from the shuttle valve 55 to the pilot pressure receiving portion, and sets the pressure by the set portions R2 and R3. Since PTO output such as rotary tillage can be increased while minimizing loss, it is possible to cope with environmental problems by improving fuel consumption.

  Further, as shown in the developed sectional view of the valve block 61 in FIG. 12, the set portion of the pilot relief R is integrally formed by configuring the relief poppet R5 and the pilot pressure receiving portion (pilot spool) R4 as separate members. In this case, it is possible to achieve a stable relief operation by securing the operability of both by means of individual axis processing without requiring the accuracy of the coaxiality.

  As shown in the hydraulic system diagram of FIG. 13, the hydraulic control circuit of the high / low switching unit 23 by the HiLo clutch at the rear stage of the traveling transmission shaft 5 is divided into one electromagnetic proportional pressure reducing valve 71 and two separate components, the Hi side and the Lo side. The on / off switching valves (solenoid valves) 72 and 72 are connected to the oil passages of the corresponding clutches 74 and 74 on the Hi side and Lo side from the travel output shaft 73 at the rear stage of the height switching unit 23, respectively.

  When switching between Hi and Lo, the hydraulic control circuit of the high / low switching unit 23 configured as described above performs control so that both are wrapped by separate on / off switching control valves 72 and 72 so as to cover the operating time of each clutch. Specifically, as shown in the clutch operation characteristic diagram of FIG. 14, the HiLo clutch switching control is performed at the same time within a predetermined rotation (for example, 40 rpm) for both the Hi side and the Lo side, and the clutch operating time is set. In consideration, the Hi side is inserted first (the cylinder operating pressures S1 and S2 are also the same), and the pressure control is performed following the variator torque as shown in the control pressure characteristic diagram of the HiLo clutch and variator in FIG. I do.

  By controlling the clutch as described above, the toroidal transmission comprising the variator 21, the planetary mechanism 22, the Hi-Lo clutch 23, etc. can cover the Hi-Lo clutch operating time when switching the Hi-Lo. While maintaining the pressure and securing the roller torque, the other pressure (S2) can be raised before releasing one pressure (S1) of the working cylinder 44a. Thereby, the shock at the time of load work can be prevented without the transmission torque being lost. In addition, as shown in the torque characteristic diagram of FIG. 15 (b), by setting the clutch torque to be 10 to 15% higher than the variator torque, it is possible to cut off sparks caused by disturbances such as tire slips and large irregularities when the aircraft is running. This prevents slippage and damage to the variator disk.

  Thus, in the toroidal transmission including the variator 21, the planetary mechanism 22, the Hi-Lo clutch 23, etc., in order to prevent the variator rollers 44 from popping out, the end load pressure is maintained and torque is secured. The clutch operating time of Hi-Lo can be covered by wrapping both by the separate on / off switching valves 72, 72. Therefore, the shock at the time of switching Hi-Lo is reduced, and the protection and durability of the variator roller including the contamination resistance can be improved.

It is a side view of the work vehicle of this invention. It is a principal part longitudinal cross-sectional view of a toroidal transmission mechanism. It is a system system | strain diagram which shows the hydraulic control example of a variator. It is an expanded view of the structural example of a valve block. It is a pressure control characteristic view showing an example of amplification control. FIG. 5 is a system diagram of another hydraulic control system. It is a structural example expansion view of a valve block. It is a hydraulic system figure which shows the roller lubrication example of a variator. It is a hydraulic system figure which shows the example of lubrication of the gear bearing of a variator, etc. It is a hydraulic system figure which shows the example of lubrication of another variator roller. It is a cross-sectional development view of the valve block of FIG. FIG. 12 is a developed sectional view of another configuration of the valve block of FIG. 11. It is a hydraulic system figure of a high-low switching part. It is a clutch operation characteristic figure of switching control of a HiLo clutch. It is a control operation characteristic figure of a HiLo clutch and a variator.

Explanation of symbols

1 Transmission 21 Variator 41, 42 Input disk 43 Output disk 44 Variator roller 44a Double acting cylinder 44b Cylinder rod 52 Reduce valve 53 Proportional pressure reducing valve 54 Variable reduce valve (pressure reducing valve)
54a Adjustment screw (pressure setting part)
54p Pilot piston 54s Spring (pressure setting part)
59 Variable relief valve 59a Adjustment screw (pressure setting part)
C1 Control characteristics C1L, C1U Control characteristics range C2 Control characteristics P Pump R Main relief S1, S2 Cylinder operating pressure

Claims (2)

The variator roller (44) for continuously variable speed transmission is connected to the extending side and the shortening side of the double acting cylinder (44a) that drives forward and backward, and the hydraulic pressures (S1, S2) on the extending side and the shortening side are respectively controlled. In a hydraulic control device for a toroidal transmission mechanism including two hydraulic control units,
The two hydraulic control units are respectively an electromagnetic proportional pressure reducing valve (53) that adjusts the hydraulic pressure in accordance with an input current signal, and a variable reduce valve (adjustable working hydraulic pressure by receiving the output pressure as a pilot pressure). 54), and the variable reduction valve (54) is provided with a pressure setting portion (54a, 54s) capable of adjusting a preload with respect to the pilot pressure, and a hydraulic control device for a toroidal transmission mechanism. The variator roller (44) for continuously variable speed transmission is connected to the extending side and the shortening side of the double acting cylinder (44a) that drives forward and backward, and the hydraulic pressures (S1, S2) on the extending side and the shortening side are respectively controlled. In a hydraulic control device for a toroidal transmission mechanism including two hydraulic control units,
The two hydraulic control units are respectively an electromagnetic proportional pressure reducing valve (53) that adjusts the hydraulic pressure in accordance with an input current signal, and a variable relief valve (59) that can adjust the holding hydraulic pressure using the output pressure as a pilot pressure. A hydraulic control device for a toroidal transmission mechanism, wherein the variable relief valve (59) is provided with a pressure setting portion (59a) capable of adjusting a preload with respect to the pilot pressure.

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