JP5750613B2 - Hydraulic continuously variable transmission - Google Patents

Description

  The present invention relates to a hydraulic continuously variable transmission (hereinafter referred to as “HST”).

  Conventionally, an input shaft, a cylinder block fixed to the input shaft, a pump swash plate arranged around the input shaft on one side of the cylinder block, and the input shaft on the other side of the cylinder block A motor swash plate disposed around the motor swash plate, and an output member rotatable integrally with the motor swash plate and relatively rotatable with respect to the input shaft. An HST including a pump plunger pressed against, a motor plunger pressed against the motor swash plate, and an oil passage connecting the pump plunger and the motor plunger is disclosed in Patent Document 1, for example. It is well known. In this HST, the rotation direction of the output member is one direction. When the pump swash plate is set to the neutral position, the motor swash plate and the output member rotate at the same speed as the cylinder block, and the pump swash plate is tilted from the neutral position to one side. As the output member decelerates, the output member decelerates as it tilts to the other side, and a wide shift range can be secured with a compact configuration. The HST is provided in a work vehicle such as a tractor provided with a front loader, for example.

  In the HST disclosed in Patent Document 1, a charge check relief valve assembly is formed by combining a relief valve for discharging oil from the oil passage and a charge check valve for supplying oil to the oil passage. Is provided in a state extending in the radial direction of the input shaft in the input shaft and connected to the oil passage. For example, when the HST is provided on a tractor with a front loader as described above, a large load is applied to the wheel when the loader is inserted into the earth and sand, and the load torque reaches the output member of the HST. This load becomes resistance against the flow of oil in the oil passage of the HST, abnormally increases the oil pressure in the oil passage, and there is a risk of damaging the prime mover that drives the HST and further the input shaft of the HST. Therefore, when the oil pressure in the oil passage becomes excessively high, the relief valve opens, and the oil is discharged from the oil passage, thereby reducing the oil pressure in the oil passage and avoiding damage to these. . Then, when the oil passage becomes low pressure, the charge check valve is opened, oil is supplied to the oil passage, and the reduced hydraulic pressure is recovered.

JP 2008-128469 A

  However, for example, the load applied to the output member at the time of work using the front loader as described above is quite high, and since it is continuously applied, during this time, the oil is drained from the oil passage and the hydraulic pressure is excessively reduced. However, simply opening the charge check valve provided in the charge check relief valve assembly may result in insufficient recovery of the oil pressure in the oil passage. If the recovery of the oil pressure in the oil passage is insufficient, cavitation occurs in the oil passage, and the transmission efficiency between the HST pump and motor due to the oil in the oil passage decreases. This problem can be solved by increasing the capacity of the charge check valve in the charge check relief valve assembly. However, as described above, the charge check relief valve assembly extends radially in the input shaft. As a result, there is a structural limitation, and in practice, it is impossible to increase the capacity of the charge check valve in the charge check relief valve assembly, or the related structure is complicated. Will occur. That is, since the charge check relief valve assembly that should be compactly configured to be provided in the input shaft is enlarged, it is necessary to enlarge the input shaft that accommodates it. Or, if an enlarged charge check relief valve assembly is arranged outside the input shaft, it will lead to an increase in the overall size of the HST, and it is necessary to change the charge / relief oil passage structure that was previously formed inside the input shaft. Occurs. In any case, it is difficult to increase the size of the charge check relief valve while ensuring the compactness of the input shaft and the entire HST.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

In claim 1, the input shaft, a cylinder block fixed to the input shaft, a pump swash plate disposed around the input shaft on one side of the cylinder block, and on the other side of the cylinder block A motor swash plate disposed around the input shaft, and an output member rotatable integrally with the motor swash plate and relatively rotatable with respect to the input shaft. A charge plunger connected to the oil passage, comprising: a pump plunger pressed against the pump swash plate; a motor plunger pressed against the motor swash plate; and an oil passage connecting the pump plunger and the motor plunger. A check relief valve assembly, the charge check relief valve assembly comprising a relief valve for discharging oil from the oil passage and a first charge check valve for supplying oil to the oil passage. In the hydraulic stepless transmission having a, in the charge check relief valve assembly, a second charge check valve to the exterior attached, the charge check relief valve assembly and the second charge check valve, provided in the input shaft, The charge check relief valve assembly extends in one radial direction of the input shaft, and the second charge check valve protrudes from the charge check relief valve assembly and extends in the other radial direction of the input shaft. It is a thing.

According to a second aspect of the present invention, the extending direction of the charge check relief valve assembly and the extending direction of the second charge check valve are perpendicular to each other .

According to a third aspect of the present invention, a third charge check valve is externally attached to the charge check relief valve assembly .

In claim 4, an input shaft, a cylinder block fixed to the input shaft, a pump swash plate arranged around the input shaft on one side of the cylinder block, and on the other side of the cylinder block A motor swash plate disposed around the input shaft, and an output member rotatable integrally with the motor swash plate and relatively rotatable with respect to the input shaft. A charge plunger connected to the oil passage, comprising: a pump plunger pressed against the pump swash plate; a motor plunger pressed against the motor swash plate; and an oil passage connecting the pump plunger and the motor plunger. A check relief valve assembly, the charge check relief valve assembly comprising a relief valve for discharging oil from the oil passage, and a charge check valve for supplying oil to the oil passage; In the hydraulic continuously variable transmission, the charge check relief valve assembly is provided with a plurality of charge check valves, and the charge check relief valve assembly and the plurality of charge check valves are provided in the input shaft, A charge check relief valve assembly extends in one radial direction of the input shaft, and each of the plurality of charge check valves protrudes from the charge check relief valve assembly to extend in the other radial direction of the input shaft. it is obtained by set.

According to a fifth aspect of the present invention, the extending direction of the charge check relief valve assembly and the extending direction of the plurality of charge check valves are perpendicular to each other .

According to a sixth aspect of the present invention, the plurality of charge check valves protrude in opposite directions from the charge check relief valve assembly .

Since the HST according to the present invention is configured as described above, the following effects can be obtained.
By configuring the HST as in claim 1, the charge check relief valve assembly itself retains the existing compactness, and the charge check relief valve assembly has the first charge check valve, the charge check relief, A sufficient amount of oil is supplied to the oil passage through a second charge check valve attached to the valve assembly.

  Further, the oil pressure in the oil passage that has been lowered by opening the relief valve is recovered, and the reduction in cavitation and transmission efficiency that occurs when the oil pressure in the oil passage is insufficient is avoided.

  Further, it is no longer necessary to provide a structure or space for providing the charge check relief valve assembly and the second charge check valve other than in the input shaft.

  Further, it is possible to avoid complication of the structure of the HST and enlargement of the entire HST.

  Further, in the input shaft, a space that does not interfere with the charge check relief valve assembly is secured in a radial direction different from the input shaft radial direction in which the charge check relief valve assembly is extended. The second charge check valve is arranged in the space, the compactness of the existing input shaft is secured, and the enlargement of the HST is avoided.

According to the second aspect of the present invention, the charge check relief valve has a radial direction different from the input shaft radial direction in which the charge check relief valve assembly is extended, the direction perpendicular to the extension direction. This is one of the directions that can secure a space that does not interfere with the assembly. In this direction, the second charge check valve protrudes from the charge check relief valve assembly, thereby maintaining the conventional compactness of the input shaft. And avoiding the increase in size of the HST.

According to the fourth aspect of the present invention, the charge check relief valve assembly itself retains the existing compactness, and a sufficient amount is provided via the plurality of charge check valves attached to the charge check relief valve assembly. The oil is supplied to the oil passage, and the oil pressure in the oil passage which has been lowered by opening the relief valve is recovered, thereby avoiding the reduction in cavitation and transmission efficiency that occurs when the oil pressure in the oil passage is insufficient.
Further, it is no longer necessary to provide a structure and space for providing a charge check relief valve assembly and a plurality of charge check valves other than in the input shaft.
Further, it is possible to avoid complication of the structure of the HST and enlargement of the entire HST.

  Further, it is not necessary to provide a structure and space for providing a charge check relief valve assembly and a plurality of charge check valves other than in the input shaft, thereby avoiding the complexity of the HST structure and the enlargement of the entire HST.

  In addition, a plurality of charge check valves are arranged in a space in the input shaft that does not interfere with the charge check relief valve assembly, so that the compactness of the conventional input shaft is ensured and the enlargement of the HST is avoided. .

According to the fifth aspect, the charge check relief valve assembly protrudes from the charge check relief valve assembly in a direction perpendicular to the extending direction of the charge check relief valve. Thus, interference with a plurality of charge check valves is reliably avoided, the conventional compactness of the input shaft is ensured, and the enlargement of the HST is avoided.

By configuring as in the sixth aspect, interference between the plurality of charge check valves is reliably avoided in the input shaft.

  The following detailed description with reference to the accompanying drawings will make the above and other objects, features, and effects of the invention more apparent.

It is a hydraulic circuit diagram of HST1. It is a perspective view of HST1. It is side surface sectional drawing of HST1. It is a plane partial sectional view of HST1. It is a rear view of HST1. It is a disassembled perspective view of HST1 in the state which excluded the servo housing 41, the pump swash plate 4, the cylinder block 3, the motor swash plate 52, and the motor swash plate holder 51. FIG. FIG. 7 is an exploded perspective view of the HST 1 in a state in which the charge check relief valve assemblies 10A and 10B are shown except for the input shaft 2 from the state of FIG.

  HST1 as an embodiment of the present invention will be described. First, the hydraulic circuit configuration of the HST 1 will be described with reference to FIG. The HST 1 includes a hydraulic pump P, a hydraulic motor M, and a pair of main oil passages 6 and 7 that connect the hydraulic pump P and the motor M to each other. The hydraulic pump P is driven by the rotation of the input shaft 2 connected to a prime mover such as an engine, and supplies and discharges oil to and from the hydraulic motor M through the pair of oil passages 6 and 7. Thus, the output member 5 provided in the hydraulic motor M is driven. The output member 5 is provided around the input shaft 2 so as to be rotatable relative to the input shaft 2, or is disposed on the same axis as the input shaft 2. As an application example of HST1, for example, the HST1 is mounted on another transmission including a gear transmission mechanism as an auxiliary transmission mechanism, and the gear transmission mechanism is driven by the rotation of the output member 5.

  The hydraulic pump P includes a pump swash plate 4 that is a movable swash plate, and the rotational speed of the output member 5 changes according to changes in the tilt direction and tilt angle of the pump swash plate 4. The rotation direction of the output member 5 is constant regardless of the tilt direction and the tilt angle of the pump swash plate 4. When the pump swash plate 4 is set to the neutral position, the amount of oil discharged from the hydraulic pump P becomes zero, and the output member 5 rotates at the same speed as the input shaft 2. The pump swash plate 4 can tilt in both directions from the neutral position, and the maximum tilt position in one direction from the neutral position is a position where the rotation speed of the output member 5 is 0, and the maximum tilt in the other direction from the neutral position. The position is a position where the rotation speed of the output member 5 is maximized.

  In this embodiment, when the pump swash plate 4 tilts from the neutral position to the side where the output member 5 is decelerated (hereinafter referred to as “low speed setting”), the main oil passage 6 is the low pressure side, and the main oil passage 7. Becomes the high pressure side, and when the pump swash plate 4 tilts from the neutral position to the speed increasing side of the output member 5 (hereinafter referred to as “high speed setting”), the main oil passage 7 is at the low pressure side and the main oil passage 6 is at the It is assumed that the high pressure side is set.

  The HST 1 is provided with a hydraulic servo mechanism S for controlling the tilting of the pump swash plate 4. The hydraulic servo mechanism S includes a hydraulic cylinder 16, a hydraulic piston 16 a provided in the hydraulic cylinder 16, and a hydraulic pilot type switching valve 17 that controls the position of the hydraulic piston 16 a by controlling the supply of pressure oil to the hydraulic cylinder 16. And an electromagnetic on-off valve 18 for controlling the hydraulic pilot type switching valve 17. A piston rod 16b extends from the hydraulic piston 16a to the outside of the hydraulic cylinder 4, and the pump swash plate 4 is connected to the tip of the piston rod 16b. Thus, the hydraulic pilot type switching valve 17 controls the supply and discharge of the servo oil to and from the hydraulic cylinder 16 based on the control of the electromagnetic on-off valve 18, thereby operating the hydraulic piston 16 a and the piston rod 16 b to operate the pump swash plate 4. The tilt is controlled. The pump swash plate 4 is connected to a hydraulic pilot type switching valve 17 through a feedback arm 4a, and the movement of the pump swash plate 4 is fed back to the hydraulic pilot type switching valve 17 so that the pump swash plate 4 is actually operated. The hydraulic pilot type switching valve 17 is controlled corresponding to the position. The electromagnetic on-off valve 18 is controlled based on a command signal from an electronic controller (not shown), and this electronic controller corresponds to an operation of a transmission operating tool provided in the vehicle, an engine speed control for driving the input shaft 2, and the like. Then, a command signal for controlling the electromagnetic on-off valve 18 is issued. The HST 1 is provided with a servo oil port 1 a for supplying oil to the electromagnetic on-off valve 18, the hydraulic pilot type switching valve 17, and the hydraulic cylinder 16.

  The HST 1 includes a pair of charge check relief valve assemblies 10 connected to the pair of main oil passages 6 and 7. Each charge check relief valve assembly 10 includes a relief valve 11 and a charge check valve 12. When the hydraulic pressure in the main oil passage 6 or 7 to which the relief valve 11 is connected becomes higher than a threshold value set for oil discharge, the relief valve 11 opens and discharges the oil from the main oil passage 6 or 7. The charge check valve 12 opens when the oil pressure in the main oil passage 6 or 7 becomes lower than a threshold set for oil supply, and supplies oil to the main oil passage 6 or 7.

  Further, at least one of the charge check relief valve assemblies 10 out of the pair of charge check relief valve assemblies 10 is provided with one or more auxiliary charge check valves 13 on the exterior. As a result, even when a large amount of oil is discharged when the relief valve 11 is opened and only the charge check valve 12 of the charge check relief valve assembly 10 is insufficient to recover the hydraulic pressure in the main oil passages 6 and 7, By supplying oil through the charge check valve 13, the oil pressure in the main oil passages 6 and 7 can be recovered, and a decrease in cavitation and transmission efficiency can be avoided.

  When the auxiliary charge check valve 13 is externally attached to only one of the pair of charge check relief valve assemblies 10, preferably, as shown in FIG. 1, the main oil passage 6 that is on the low pressure side when the low speed is set. An auxiliary charge check valve 13 is externally attached to the charge check relief valve assembly 10 connected to, and the auxiliary charge check valve 13 is connected to the main oil passage 6. The amount of oil discharged due to the opening of the relief valve 11 is excessive because it is a phenomenon that occurs at the time of low speed setting in which work (for example, soil sanding work using a loader) is performed. Accordingly, a large amount of oil is discharged from the main oil passage 7 on the high pressure side at the time of low speed setting through the relief valve 11 of the charge check relief valve assembly 10 connected to the main oil passage 7. Sufficient oil is supplied from the charge check valve 12 and the auxiliary charge check valve 13 of the charge check relief valve assembly 10 connected to the main oil passage 6 to the main oil passage 6 on the low pressure side when the low speed is set. The amount of oil discharged from the oil passage 7 is compensated.

  HST1 is provided with a charge oil port 1b for supplying charge oil to both charge check relief valve assemblies 10, and is connected to a charge oil source such as a charge pump disposed outside HST1. The charge oil port 1b and both charge check relief valve assemblies 10 are connected by the charge oil passage 8, and when the charge check valve 12 (and the auxiliary charge check valve 13) is opened, the charge oil passage 8 is connected to the charge oil port 1b. The oil supplied to is supplied to the main oil passage 6 or 7. Further, when the drain oil passage 9 is branched from the charge oil passage 8 and the relief valve 11 is opened, the oil is discharged from the main oil passage 6 or 7 to the drain oil passage 9. Further, the HST 1 is provided with a pressure regulating valve 15 for adjusting the hydraulic pressure of the charge oil, and a pressure regulating oil port 1 c for guiding a part of the charge oil to the pressure regulating valve 15. Yes.

  Next, examples relating to the structure of the HST 1 will be described with reference to FIGS. The HST 1 has the input shaft 2 as described in the description of the hydraulic circuit structure in FIG. One end of the input shaft 2 protrudes as a connection end 2a connected to a prime mover such as an engine. Hereinafter, the present embodiment will be described on the assumption that the connection end 2a is the front end 2a of the input shaft 2 and the input shaft 2 extends in the front-rear horizontal direction.

  As shown in FIGS. 2 to 4, the cylinder block 3 is mounted on the outer peripheral surface of the front and rear middle portion of the input shaft 2 so as not to be relatively rotatable (that is, the cylinder block 3 is fixed to the input shaft 2). A motor swash plate assembly 50 is formed around the input shaft 2 in front of the cylinder block 3, and a pump swash plate assembly 40 is formed around the input shaft 2 behind the cylinder block 3.

  2 to 5 and the like, the pump swash plate assembly 40 is configured by combining a servo housing 41, a pump swash plate holder 42, the aforementioned pump swash plate 4, and the like. The swash plate holder 42 is fixed to the front portion of the servo housing 41, and the movable swash plate 4 is mounted on the pump swash plate holder 42 so as to tilt forward and backward. The servo housing 41 is mounted on the circumferential surface of the input shaft 2 so as to be relatively rotatable via a bearing 43. For example, in an application example in which the HST1 is a main transmission mechanism and the gear transmission mechanism is an auxiliary transmission mechanism. It is conceivable to fix the servo housing 41 to the housing that houses the gear transmission mechanism.

  As shown in FIGS. 3 and 4, a hydraulic cylinder 16 of the hydraulic servo mechanism S is formed in the servo housing 41. A hydraulic piston 16a is mounted in the hydraulic cylinder 16 and is located in front of the hydraulic piston 16a. The front end of the piston rod 16b extending to the front protrudes forward from the servo housing 41, and a coupling head 16c is fixed to the front end of the piston rod 16b as shown in FIGS. As shown in FIGS. 2 to 4, a pair of arms 4b are extended upward from the pump swash plate 4, and both arms 4b are arranged on the left and right sides of the connecting head 16c. As shown, it is pivotally supported by the connecting head 16c via a horizontal pivot pin 4c. As a result, the piston swash plate 4 is connected to the hydraulic piston 16a / piston rod 16b via the connecting head 16c, and the piston swash plate 4 is tilted by sliding in the front-rear direction of the hydraulic piston 16a / piston rod 16b. It is supposed to be.

  The servo housing 41 is further provided with a hydraulic pilot type switching valve 17 and an electromagnetic on-off valve 18 of the hydraulic servo mechanism S. The hydraulic pilot type switching valve 17 is mounted in the servo housing 41 vertically from the upper end of the servo housing 41, as shown in FIGS. As shown in FIG. 5, the servo housing 41 is attached to the rear end surface, and the spool is fitted into the servo housing 41. As shown in FIGS. 2, 3, and 5, the feedback arm 4 a is extended along one left and right side surfaces of the servo housing 41 (in this embodiment, the right side surface toward the front). The front end of the feedback arm 4 a is pivotally supported by the pump swash plate 4, and the rear end is pivotally supported by the servo housing 41 and is connected to the hydraulic pilot type switching valve 17 in the servo housing 41. Further, as shown in FIGS. 2, 4, and 5, a servo oil port 41a corresponding to the servo oil port 1a in FIG. Further, as can be seen from FIGS. 6 and 7, a pressure regulating valve 15 is disposed in the servo housing 41, and on the rear end surface of the servo housing 41, as shown in FIG. A pressure regulating port 41b corresponding to the pressure regulating port 1c in FIG.

  2 to 4 and the like, the motor swash plate assembly 50 is configured by combining the output member 5, the motor swash plate holder 51, the motor swash plate 52, and the like. As shown in FIG. 4, the rear end of the output member 5 and the front end of the motor swash plate holder 51 are joined together, and the output member 5 and the motor swash plate holder 51 are fastened with bolts so as to be integrated. The joined output member 5 and motor swash plate holder 51 are mounted on the circumferential surface of the input shaft 2 via a bearing 53 so as to be relatively rotatable. For example, in the application example described above, the output member 5 is fixedly provided with a gear that is linked and linked to a gear transmission mechanism as an auxiliary transmission mechanism. As shown in FIGS. 2 to 4, a motor swash plate 52 is provided at the rear end portion of the motor swash plate holder 51 so as to be rotatable integrally with the motor swash plate holder 51. Thus, the motor swash plate 52, the swash plate holder 51, and the output member 5 are disposed around the input shaft 2 so as to be rotatable relative to the input shaft 2 integrally as a whole of the motor swash plate assembly 50. ing.

  As shown in FIGS. 2 to 4, the cylinder block 3 includes a plurality of pump plungers 31 constituting the hydraulic pump P, and a plurality of motor plungers 32 constituting the hydraulic motor M, the same number as the pump plunger 31. Is provided. In this regard, although not clearly shown in the present application, the pump plunger hole 3a and the motor plunger are disposed in the cylinder block 3 on the circumference centering on the input shaft 2 when viewed in the axial direction of the input shaft 2. The holes 3b are alternately arranged, and the pump plungers 31 are fitted into the respective pump plunger holes 3a, and the motor plungers 32 are fitted into the respective motor plunger holes 3b so as to be reciprocally movable in the axial direction of the input shaft 2. Yes. 2 to 4, the head of the pump plunger 31 protrudes rearward from the cylinder block 3 and is pressed against the pump swash plate 4, and the head of the motor plunger 32 is from the cylinder block 3. It protrudes forward and is pressed against the motor swash plate 52.

  Further, as shown in FIGS. 2 and 4, the cylinder block 3 includes a plurality of pump spool valve holes 3c communicating with the pump plunger holes 3a and a plurality of motor spool valve holes 3d communicating with the motor plunger holes 3b. 2 to 4, the pump spool valve 33 is provided in each pump spool valve hole 3c, and the motor spool valve 34 is provided in each motor spool valve hole 3d. 2 is slidably fitted in the axial direction. As shown in FIGS. 3 and 4, the head of the pump spool valve 33 protrudes rearward from the cylinder block 3, and as can be seen from FIGS. 2 to 4, 5, and 6, Between the rear end and the front end portion of the servo housing 41, it is fitted in a groove 44 a formed in the spool valve retainer 44 mounted on the input shaft 2. On the other hand, as shown in FIGS. 2 to 4, the head of the motor spool valve 34 projects forward from the cylinder block 3, and as can be seen in FIGS. 2 to 4, 5, and 6, the cylinder block 3 is inserted into a groove 54 a formed in the spool valve retainer 54 mounted on the input shaft 2 between the front end of the swash plate holder 51 and the rear end of the swash plate holder 51.

  All pump spool valve holes 3c and all motor spool valves 3d communicate with each other via oil passages 3e and 3f formed in the cylinder block 3 shown in FIG. 3, and the oil passage 3e is the main oil shown in FIG. The oil path 3f corresponds to the path 6 and corresponds to the main oil path 7 in FIG.

  As shown in FIG. 3, an oil passage 2b in the front-rear horizontal direction is formed in the input shaft 2 along the axis. As shown in FIGS. 3 and 5, the oil passage 2b is opened at the rear end of the input shaft 2 protruding rearward from the servo housing 41. The opening end of the oil passage 2b is shown in FIG. The charge oil port 2c corresponds to the charge oil port 1b. Further, as can be seen in FIGS. 3, 4, 6, and 7, the oil passage 2b is connected to the oil passage 3e (that is, the main oil passage 6) in the portion of the input shaft 2 surrounded by the cylinder block 3. Charge check relief valve assembly 10 (referred to as “10A”) and charge check relief valve assembly 10 (referred to as “10B”) capable of communicating the oil passage 2b with the oil passage 3f (ie, the main oil passage 7). Are arranged side by side. Each charge check relief valve assembly 10 extends in the diameter direction of the input shaft 2, and when viewed in the axial direction of the input shaft 2, one charge check relief valve assembly 10 is the other charge check relief valve assembly 10. It extends in the direction perpendicular to the direction.

  In the present embodiment, the oil passage 2b and the oil passage 3e can be communicated with the charge check relief valve assembly 10A that is arranged to communicate with the oil passage 3e that becomes the low pressure side at the low speed setting and the high pressure side at the high speed setting. The two auxiliary (second and third) charge check valves 13 are externally provided, and the charge check relief valve assembly is arranged so as to be able to communicate with the oil passage 3f which is on the high pressure side at the low speed setting and on the low pressure side at the high speed setting. 10B is provided with one auxiliary (second) charge check valve 13 that is configured to allow the oil passage 2b and the oil passage 3f to communicate with each other. Each auxiliary charge check valve 13 protrudes from the middle portion of the charge check relief valve assembly 10 attached to the exterior thereof, and the radius of the input shaft 2 is perpendicular to the extending direction of the charge check relief valve assembly 10. It extends in the direction. Further, the two auxiliary (second and third) charge check valves 13 attached to the exterior of the charge check relief valve assembly 10A protrude from the charge check relief valve assembly 10A in opposite directions. Thus, the auxiliary charge check valve 13 can be disposed in the limited space in the input shaft 2 without hindering the existing compactness of the two charge check relief valve assemblies 10A and 10B. .

  At the time of high speed setting, the relief valve 11 of the charge check relief valve assembly 10A is opened to discharge oil from the oil passage 3e (main oil passage 6), while the charge check valve 12 and the charge check relief of the charge check relief valve assembly 10B are discharged. One auxiliary charge check valve 13 externally attached to the valve assembly 10B is opened to supply oil to the oil passage 3f (main oil passage 7). On the other hand, at the time of low speed setting, the relief valve 11 of the charge check relief valve assembly 10B opens to discharge oil from the oil passage 3f (main oil passage 7), while the charge check valve 12 of the charge check relief valve assembly 10A and the charge are discharged. Two auxiliary charge check valves 13 externally attached to the check relief valve assembly 10A are opened to supply oil to the oil passage 3e (main oil passage 6). The oil discharge amount from the relief valve 11 of the charge check relief valve assembly 10B tends to be larger than the oil discharge amount from the relief valve 11 of the charge check relief valve assembly 10A when the operation is performed at a low speed setting, Considering this, at the time of low speed setting, the charge check relief valve supplies more oil than the amount of oil supplied by the charge check valve 12 and one auxiliary charge check valve 13 of the charge check relief valve assembly 10B at the time of high speed setting. It is supplied by the charge check valve 12 and the two auxiliary charge check valves 13 of the assembly 10A.

  A portion of the oil passage 2b between the charge oil port 2c and the charge check relief valve assembly 10A corresponds to the charge oil passage 8 in FIG. 1, and the oil in this portion has a charge pressure. , Flows forward from the charge oil port 2c and is supplied to the charge check relief valve assembly 10A. On the other hand, a portion of the oil passage 2b in front of the charge check relief valve assembly 10B corresponds to the drain oil passage 9 in FIG.

  When the low speed is set, the oil discharged from the relief valve 11 of the charge check relief valve assembly 10B flows into a portion of the oil passage 2b corresponding to the drain oil passage 9 ahead of the charge check relief valve assembly 10B. The charge check relief valve assembly 10A is supplied to the oil passage 2b through a portion between the charge check relief valve assemblies 10A and 10B. The charge check valve 12 of the charge check relief valve assembly 10A and the two charge check valves 13 attached to the exterior of the charge check relief valve assembly 10A are connected to a charge oil port 2c corresponding to the charge oil passage 8 of the oil passage 2b. Charge oil is supplied to the oil passage 3e from the portion between the charge check relief valve assembly 10A and the portion of the oil passage 2b between the charge check relief valve assemblies 10A and 10B.

  On the other hand, at the time of high speed setting, oil that has passed through the charge check relief valve assembly 10A from the portion of the oil passage 2b between the charge oil port 2c corresponding to the charge oil passage 8 and the charge check relief valve assembly 10A, and the charge Oil discharged from the relief valve 11 of the check relief valve assembly 10A flows to a portion of the oil passage 2b between the charge check relief valve assemblies 10A and 10B. The charge check valve 12 of the charge check relief valve assembly 10B and the charge check valve 13 attached to the exterior of the charge check relief valve assembly 10B include a portion of the oil passage 2b between the charge check relief valve assemblies 10A and 10B, Charge oil is supplied to the oil passage 3f from a portion of the oil passage 2b corresponding to the drain oil passage 9 ahead of the charge check relief valve assembly 10B.

  The above is a recommended example of the present invention, and various modifications and applications that can be easily conceived by those skilled in the art are possible without departing from the technical scope defined by the claims.

  The HST according to the present invention can be applied to various types of vehicles and industrial machines such as the above-described tocter with front loader.

1 Hydraulic continuously variable transmission (HST)
2 Input shaft
3 Cylinder block 3e Oil passage 3f Oil passage 4 Pump swash plate 5 Output member 10 (10A, 10B) Charge check relief valve assembly 11 (provided in the charge check relief valve assembly 10) Relief valve 12 (in charge check relief valve assembly 10) Provided first) charge check valve 13 Auxiliary (second / third) charge check valve 31 Pump plunger 32 Motor plunger 40 Pump swash plate assembly 50 Motor swash plate assembly

Claims (6)

An input shaft, a cylinder block fixed to the input shaft, a pump swash plate arranged around the input shaft on one side of the cylinder block, and around the input shaft on the other side of the cylinder block A motor swash plate that is disposed, and an output member that can rotate integrally with the motor swash plate and that can rotate relative to the input shaft. A pump plunger, a motor plunger pressed against the motor swash plate, an oil passage connecting the pump plunger and the motor plunger, and a charge check relief valve assembly connected to the oil passage The charge check relief valve assembly includes a relief valve for discharging oil from the oil passage, and a first charge check valve for supplying oil to the oil passage. In the device,
The charge check relief valve assembly is provided with a second charge check valve,
The charge check relief valve assembly and the second charge check valve are provided in the input shaft, the charge check relief valve assembly extends in a radial direction of the input shaft, and the second charge check valve is A hydraulic continuously variable transmission characterized in that it protrudes from the charge check relief valve assembly and extends in the other radial direction of the input shaft . The hydraulic continuously variable transmission according to claim 1, wherein the extending direction of the charge check relief valve assembly and the extending direction of the second charge check valve are perpendicular to each other . The hydraulic continuously variable transmission according to claim 1 , wherein a third charge check valve is externally attached to the charge check relief valve assembly . An input shaft, a cylinder block fixed to the input shaft, a pump swash plate arranged around the input shaft on one side of the cylinder block, and around the input shaft on the other side of the cylinder block A motor swash plate that is disposed, and an output member that can rotate integrally with the motor swash plate and that can rotate relative to the input shaft. A pump plunger, a motor plunger pressed against the motor swash plate, an oil passage connecting the pump plunger and the motor plunger, and a charge check relief valve assembly connected to the oil passage The charge check relief valve assembly includes a relief valve for discharging oil from the oil passage and a charge check valve for supplying oil to the oil passage. In,
A plurality of charge check valves are externally attached to the charge check relief valve assembly,
The charge check relief valve assembly and the plurality of charge check valves are provided in the input shaft;
The charge check relief valve assembly extends in one radial direction of the input shaft, and the plurality of charge check valves protrude from the charge check relief valve assembly in the other radial direction of the input shaft. A hydraulic continuously variable transmission that is extended . Hydraulic stepless transmission according to claim 4, characterized in that the extending direction and the extension direction and the perpendicular to one another of said plurality of charge check valves of the charge check relief valve assembly. 6. The hydraulic continuously variable transmission according to claim 4 , wherein the plurality of charge check valves protrude in opposite directions from the charge check relief valve assembly .

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