JP4714916B2 - Vehicle power transmission mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a vehicle power transmission mechanism including a hydrostatic and mechanical continuously variable transmission (HMT) having a hydrostatic continuously variable transmission (HST) and a planetary gear device.
[0002]
[Prior art]
  Conventionally, an HMT in which an HST and a planetary gear device are combined has been used in order to continuously change the rotational driving force from a drive source at a large speed ratio.
  Such an HMT generally inputs an HST shift output to any one of the three elements of the planetary gear device, inputs an output from a drive source to the other element, and the remaining one element. Thus, a continuously variable transmission output with a larger gear ratio can be obtained by changing the HST output.
[0003]
  FIG. 18 shows theoretical operation characteristics in one embodiment of the HMT. In FIG. 18, the output of HST is input to the sun gear of the planetary gear device, the output from the drive source is inverted and input to the planet carrier, and the drive force from the internal gear to the drive wheel is output. The theoretical operation characteristics of the HMT configured as shown in FIG.
  As shown in FIG. 18, in HMT, the HMT output is theoretically set to 0 output (neutral state) by swinging the swash plate of HST (in FIG. 18, maximum inclination to the deceleration side). can do.
[0004]
  However, in practice, it is difficult to set the HMT to the neutral state for the following reasons. That is, as shown in FIG. 18, in order to bring the HMT into the neutral state, it is necessary to rotate the HST output shaft (motor shaft) at a high speed. However, the rotation of the HST output shaft varies depending on the volumetric efficiency of the HST. The HST volumetric efficiency varies depending on the oil temperature of the HST hydraulic oil and the load applied to the HST output shaft. Therefore, it is possible that the output shaft of the HMT actually rotates despite the fact that the HST swash plate is tilted to the theoretical tilt angle that causes the HMT to be in a neutral state. For example, when the HST swash plate is swung by a predetermined theoretical angle, the HMT can be in a neutral state on a flat ground, thereby interrupting the power transmission to the drive wheel, but on an inclined ground, The load on the output shaft causes the HMT output shaft to rotate in the forward direction, which may cause power transmission to the drive wheels.
  Such unintentional power transmission to the drive axle causes inconveniences such as excessive wear of the brake device and an increase in capacity due to an increase in capacity, and movement against the intention of the vehicle.
[0005]
[Problems to be solved by the invention]
  The present invention has been made to solve the above-described problems, and includes an HMT.And a pair of left and right first and second brake devicesA power transmission mechanism comprising:When only one of the first and second brake devices is operated, the vehicle is stopped by operating both the first and second brake devices while maintaining the output of the driving force from the HMT. If you want to drive power output from the HMTProviding a power transmission mechanism that can reliably preventEyesTarget.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides a drive source.A pair of left and rightA power transmission mechanism for a vehicle that transmits a driving force to driving wheels, comprising a hydraulic pump, a hydraulic motor, and a pair of hydraulic lines that fluidly connect the two, and continuously rotating the rotational driving force from the driving source. Output from the hydrostatic continuously variable transmission, and the first element of the three elements is an output from the hydrostatic continuously variable transmission. And a planetary gear device configured to be able to extract a speed change driving force from the second element of the three elements, and the planetary gear device.A differential device that differentially branches the driving force to the pair of driving wheels, and a pair of first and second members that individually apply braking force to the pair of driving wheels, respectively.With brake device,in frontThe first essential point of the planetary gear deviceElementLet it be freeGainWith a release mechanismThe release mechanism is a switching valve for communicating or blocking between the pair of hydraulic lines, the switching valve being biased toward the blocking position by a biasing member, and a mechanical link for operating the switching valve A first connecting rod having one end rotatably connected to a swing arm for operating the first brake device, and one end operating the second brake device. A second connecting rod rotatably connected to the swinging arm, a common rod rotatably connected to the other ends of the first and second connecting rods, and movement of the common rod in the longitudinal axis direction And a link mechanism that positions the switching valve at the communication position against the urging force of the urging member, and the longitudinal axes of the first and second connecting rods are the longitudinal axes of the common rods. In contrast, they are arranged so as to be inclined at substantially the same angle in opposite directions. It is, the common rod moves longitudinally only when both of said first and second brake device is actuatedA power transmission mechanism is provided.
[0007]
  Preferably, the switching valve is a high-pressure relief valve that causes one hydraulic fluid line to communicate with the other hydraulic fluid line when the hydraulic pressure of one hydraulic fluid line of the pair of hydraulic fluid lines exceeds a predetermined pressure..
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
  Hereinafter, a power transmission mechanism according to a first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a transmission structure of a vehicle provided with a power transmission mechanism 100 according to the present embodiment. FIG. 2 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism.
  As shown in FIGS. 1 and 2, the power transmission mechanism 100 transmits a driving force from the driving source 10 to the driving wheels 20, and includes an HST 30, a planetary gear device 40, and a brake device 50. ing.
[0009]
  The HST 30 includes a hydraulic pump 31 having a pump shaft 30a operatively connected to the drive source 10, a hydraulic motor 32 having a motor shaft serving as an HST output shaft 30b, and a fluid between the hydraulic pump 31 and the hydraulic motor 32. And a pair of hydraulic lines 33 connected to each other. At least one of the hydraulic pump 31 and the hydraulic motor 32 is a variable displacement type that can change the suction / discharge amount. In the present embodiment, the hydraulic pump 31 is a variable displacement type in which the suction / discharge amount is changed by operation of the swash plate. The rotation speed can be changed. In the present embodiment, the rear end portion in the transmission direction of the pump shaft 30a extends rearward through the hydraulic pump body, and the rear end portion of the pump shaft and the PTO drive shaft 60 are connected to each other. It is connected.
[0009]
  The planetary gear device 40 includes a sun gear 41, a planet carrier 43 that rotates according to the revolution of the planetary gear 42 that meshes with the sun gear 41, and an internal gear 44 that meshes with the planetary gear 42. The HST output shaft 30b is operatively connected to the first element among the three elements of the sun gear 41, the planet carrier 43 and the internal gear 44 in the planetary gear device 40, and the second element to the first element The shift output transmitted to the drive wheel 20 can be taken out. In the present embodiment, the driving force from the driving source 10 is operatively input to the remaining third element in the planetary gear device, whereby a large gear ratio is obtained. It has come to be obtained.
[0010]
  In the present embodiment, as shown in FIG. 1, the HST output shaft 30b and the sun gear 41 are operatively connected, and the PTO drive shaft 60 and the planet carrier 43 are operatively connected. The shift output from the internal gear 44 to the drive wheel 20 is taken out.
[0011]
  The brake device 50 can cut off power transmission from the planetary gear device 40 to the drive wheels 20 in accordance with an operation of an operation member 51 such as a brake pedal or a brake lever provided in a driver's seat or the like. .
  The vehicle in the present embodiment branches and transmits the driving force from the HMT to a pair of driving axles 22 that are differentially driven through a differential device 21 such as a differential gear device or a side clutch device. It is configured as follows. The brake device 50 is a mechanical turn brake device including first and second brake devices 50a and 50b that individually act on each of the pair of drive axles.
[0012]
  Specifically, as shown in FIG. 2, the first and second brake devices 50a and 50b include a first and second operation members 51a and 51b, and the first and second operation members 51a and 51b, respectively. The first and second support shafts 52a and 52b support the first and second operation members 51a and 51b so as not to rotate relative to the first and second support shafts 52a and 52b. First and second drives supported by first and second swing arms 53a and 53b swinging in response to an operation and first and second drive axles 22a and 22b so as not to rotate relative to each other and not to slide axially. The first and second friction plates 54a and 54b and the first and second drive axles 22a and 22b are slidable and engaged / disengaged with the drive friction plate 54. Second fixed friction plates 55a and 55b (FIG. 1) and First and second pushing members (not shown) for pushing the first and second fixed friction plates 55a and 55b (FIG. 1) toward the driving friction plates 54a and 54b, and the first And first and second connecting members 56a and 56b for connecting the second swing arms 53a and 53b and the first and second pushing members.
[0013]
  The brake device 50 having such a configuration operates as follows. That is, when the operation member 51 is operated, the swing arm 53 swings around the support shaft 52, and thereby the connecting member 56 moves. The movement of the connecting member 56 causes the pushing member to push the fixed side friction plate 55 toward the driving side friction plate 54 and frictionally engage them. Thereby, rotation of the corresponding drive axle 22 stops. In addition, the code | symbol 65 and the code | symbol 90 in FIG. 1 are the forward / reverse switching clutch apparatus and the flywheel respectively arrange | positioned between the said HMT and a differential gear.
[0014]
  The power transmission mechanism 100 according to the present embodiment further includes a release mechanism 110 that brings the first element of the planetary gear device 40 into a free state in accordance with the braking operation of the brake device 50. Note that the braking operation of the brake device 50 refers to the operation of the brake device for stopping the vehicle. Therefore, when the brake device 50 is a turn brake type device including the first and second brake devices 50a and 50b as in the present embodiment, both the first and second brake devices 50a and 50b are operated. It refers to the state to be made.
[0015]
  The release mechanism 110 is disposed between a pair of hydraulic lines 33 in the HST 30, and an opening / closing device 120 that communicates / blocks the pair of hydraulic lines, and the opening / closing device 120 according to a braking operation of the brake device 50. And a mechanical link device 130 for operating the device.
[0016]
  As shown in FIG. 2, the opening / closing device 120 includes first and second bypass lines 121a and 121b, and first and second bypass lines 121a whose base ends communicate with the pair of hydraulic lines 33, respectively. , 121b, and a switching valve 122 that communicates / blocks the first and second bypass lines 121a, 121b.
[0017]
  FIG. 3 shows a longitudinal sectional view of the switching valve 122. As shown in FIG. 3, the switching valve 122 includes a valve housing 123 having a hollow portion whose tip is closed, and a piston 124 that is liquid-tightly and slidably inserted into the hollow portion of the valve housing 123. And an urging member 125 disposed between the closed front end portion of the hollow portion and the piston front end portion. In a normal state, the first and second bypass lines 121a and 122b are blocked, and the When the piston 124 is pressed toward the distal end side of the housing 123 against the urging force of the urging member 125, the first and second bypass lines 121a and 121b are communicated with each other.
[0018]
  More specifically, the valve housing 123 has first and second openings 123a and 123b that respectively connect the distal end portions of the first and second bypass lines 121a and 121b and the hollow portion.
[0019]
  One end of the piston 124 extends outward from the valve housing 123, and the other end of the outer extension 124a extends from the other end to the tip side. A first large-diameter portion 124b that is dense and slidable; a first small-diameter portion 124c that extends from the first large-diameter portion 124b toward the distal end; and the hollow portion that extends from the first small-diameter portion 124c toward the distal end. A second large-diameter portion 124d that is liquid-tight and slidable, a second small-diameter portion 124e that extends from the second large-diameter portion 124d to the distal end side, and extends from the second small-diameter portion 124e to the distal-end side, A third large-diameter portion 124f that is liquid-tight and slidable with respect to the hollow portion, and a communication hole 124g that communicates the outer surface of the first small-diameter portion and the outer surface of the second small-diameter portion are provided.
[0020]
  In the normal state where there is no operation from the outside, the piston 124 has the second large diameter portion 124d opposed to the first opening 123a and / or the third large diameter portion 124f has the second opening 123b. Thus, the first bypass line 121a and the second bypass line 121b are blocked.
[0021]
  On the other hand, when the piston 124 is pushed to the tip side by an operation from the outside, the first small diameter portion 124c faces the first opening 123a, and the second small diameter portion 124e becomes the second opening 123b. Thus, the first bypass line 121a and the second bypass line 122b communicate with each other.
[0022]
  More preferably, as shown in FIG. 3, the proximal end side of the second large diameter portion 124d is cut into a gap between the first small diameter portion 124c and the inner peripheral surface of the hollow portion, and the distal end side is reached. Accordingly, a tapered groove 124h having a narrow width can be formed. The groove 124h becomes a part of the communication path between the first bypass line 121a and the second bypass line 121b when the piston 124 is pushed to the tip side. By providing such a groove 124h, the communication passage diameter between the first bypass line 121a and the second bypass line 121b can be gradually increased in accordance with the amount of movement (brake operation amount) of the piston 124 toward the tip side. A variable aperture function can be obtained. Such a variable throttle function can prevent a sudden flow of oil between the pair of hydraulic lines 33 in a transition period during brake braking, and can gradually increase or decrease the output torque of the hydraulic motor 32. Therefore, the brake is released. It is possible to travel at a very low speed.
[0023]
  Hereinafter, the link device 130 will be described.
  As shown in FIG. 2, the link device 130 has a first connecting rod 131a having one end rotatably connected to the swing arm 53a of the first brake device 50a, and one end being the second brake device. The second connecting rod 131b is rotatably connected to the swing arm 53b of the 50b, and the common rod 132 is rotatably connected to the other ends of the first and second connecting rods 131a and 131b. .
  The first connecting rod 131a and the second connecting rod 131b are arranged such that their respective longitudinal axes are inclined at substantially the same angle in opposite directions with respect to the longitudinal axis of the common bar 132.
[0024]
  The link device 130 further pushes the piston 124 against the urging force of the urging member 125 in accordance with the movement of the common rod 132 in the longitudinal axis direction, and the switching valve 122 is in a communication state. A link mechanism 140 is provided.
[0025]
  The link mechanism 140 includes, for example, a first swinging member 141 that is rotatably connected to the common rod 132, and a first rotating shaft 142 that rotates about an axis in accordance with the swinging of the first swinging member 141. And a second swinging member 143 that swings according to the rotation of the first rotating shaft 142 around the axis, a second rotating shaft 144, and a swing according to the rotation of the second rotating shaft 144 around the axis. A third swinging member 145 for pushing the piston 124 against the biasing force of the biasing member 125; a fourth swinging member 146 connected to the second rotating shaft 144; A connecting member 147 for connecting the second swing member 143 and the fourth swing member 146 so as to swing the fourth swing member 146 in response to the swing of the swing member 143; it can.
[0026]
  Hereinafter, regarding the operation of the link device 130, (i) when only one of the first or second brake devices 50a and 50b is operated, and (ii) both the first and second brake devices 50a and 50b. An example will be described in which the is operated.
[0027]
(i) When only one of the first and second brake devices 50a and 50b is operated
  As in the present embodiment, in a vehicle having a pair of drive axles 22a and 22b that are driven differentially with each other, and each of the pair of drive axles 22a and 22b is provided with a brake device 50, In order to perform a sharp turn or the like, there are cases where only a brake device provided on one drive axle is operated. In such a case, the driving force from the driving source must be continuously transmitted to the other driving axle. The link device 130 is configured not to operate the opening / closing device 120 when only one of the brake devices is not intended to brake such a vehicle.
[0028]
  For example, it is assumed that the driver operates only the first brake device 50a. In this case, only the first connecting rod 131a tries to move along the longitudinal direction. Therefore, a force along the arrow F1 (see FIG. 2) is applied to the common bar 132. As described above, the first connecting rod 131a and the common rod 132 are connected so as to be relatively rotatable, and the first connecting rod 131a is inclined at a predetermined angle with respect to the common rod 132. The common bar 132 swings in the clockwise direction in FIG. 2 around the connection point with the first swing member 141 by the force along the arrow F1. That is, the common bar 132 does not move in the longitudinal direction. Therefore, the first rotating shaft 142 does not rotate and the piston 124 is not pushed.
  As described above, the link device 130 maintains the switching device 120 in the shut-off state when only one of the first and second brake devices 50a and 50b is operated.
[0029]
(ii) When both the first and second brake devices 50a and 50b are operated
  When both the first and second brake devices 50a and 50b are operated, that is, when the brake device is operated to stop the vehicle, the link device 130 operates as follows.
  That is, when the driver operates both the first and second brake devices 50a and 50b, both the first and second connecting rods 131a and 131b move along the longitudinal direction. Accordingly, both the force along the arrow F1 and the force along the arrow F2 are loaded on the common bar 132.
[0030]
  Here, if the forces F1 and F2 are decomposed into the x-axis direction along the longitudinal direction of the common bar 132 and the y-axis direction perpendicular to the longitudinal direction of the common bar 132, F1y and F2y cancel each other. The common bar 132 is loaded with the resultant force of F1x and F1y.
  Accordingly, the common bar 132 moves along the longitudinal direction, whereby the first rotating shaft 142 rotates around the axis and the second swinging member 143 swings. The swing of the second swing member 143 swings the third swing member 145 via the connecting member 147, so that the piston 124 resists the biasing force of the biasing member 125. Is pushed.
  Thus, the link device 130 brings the opening / closing device 120 into a communication state in accordance with a braking operation in which both the first and second brake devices 50a and 50b are operated.
[0031]
  In the power transmission mechanism 100 having such a configuration, the following effects can be obtained.
  That is, when the driver operates both the first and second brake devices 50a and 50b to stop the vehicle, the opening / closing device 120 communicates with the pair of hydraulic lines 33 according to the braking operation of the brake device. Let it be in a state. When the pair of hydraulic lines 33 are in communication, the motor shaft 30b and the first element (the sun gear 41 in the present embodiment) of the planetary gear device 40 connected to the motor shaft are in a free state.
[0032]
  When any one of the input side elements in the planetary gear device is in a free state, the planetary gear device 40 is in a non-output state. In the present embodiment, the sun gear 41 that functions as the first element is configured to be in a free state, thereby driving the planet carrier 43 that functions as the third element (the other input side element). Regardless of the input of force, the internal gear 44 that functions as the second element (output side element) does not rotate.
[0033]
  On the other hand, when turning only one of the first and second brake devices 50a and 50b when the vehicle is turned sharply, the pair of hydraulic lines 33 are not communicated. Accordingly, the driving force is output from the HMT as usual.
[0034]
  As described above, in the present embodiment, the first element which is the input side element in the planetary gear device 40 is brought into the free state in accordance with the braking operation of the brake device 50, so that the vehicle is stopped. If desired, the HMT can be set to no output. Therefore, it is possible to effectively prevent an increase in cost associated with excessive wear of the brake device and an increase in capacity, and movement contrary to the intention of the vehicle.
[0035]
Embodiment 2. FIG.
  Hereinafter, a preferred second embodiment 200 of a power transmission mechanism according to the present invention will be described with reference to the accompanying drawings. FIG. 4 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 200 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member in the said Embodiment 1, and the description is abbreviate | omitted.
[0036]
  The power transmission mechanism 200 according to the present embodiment has an opening / closing device 220 having a high-pressure relief valve 222 with a release mechanism instead of the opening / closing device 120 having the switching valve 122 in the first embodiment. Yes.
[0037]
  FIG. 5 is a longitudinal sectional view of the high-pressure relief valve 222 with a release mechanism. As shown in FIG. 5, the high-pressure relief valve 222 with a release mechanism includes a first oil chamber 223a and a first oil passage 223a communicated with the first and second bypass lines 121a and 121b on one end side and the other end side, respectively. A valve housing 223 having a valve seat 22cd having two oil chambers 223b and having a communication hole 223c communicating with the first and second oil chambers 223a, 223b at a substantially central portion in the axial direction; A valve body 224 accommodated in the second oil chamber 223b, a biasing member 225 for pressing the valve body 224 toward the valve seat 223d, and the valve body 224 against the biasing force of the biasing member 225. And a push member 226 that can be externally operated to push away from the valve seat 223d.
[0038]
  The pushing member 226 moves the valve body 224 away from the valve seat 223d through the link device 130 only during brake braking in which both the first and second brake devices 50a and 50b are activated. Push.
  Note that when the vehicle is driven, the vehicle is often moved forward rather than moved backward. Therefore, it is preferable that a line of the pair of hydraulic lines 33 that has a high pressure when traveling forward is communicated with the first bypass line 121a and a high pressure when traveling backward. Can be communicated with the second hydraulic line 121b.
[0039]
  In the present embodiment, the same effects as in the first embodiment can be obtained, and unreasonable due to the influence of an excessive load acting during forward traveling on the high pressure line of the pair of hydraulic lines 33. Effective oil pressure rise can be effectively prevented.
[0040]
Embodiment 3 FIG.
  Hereinafter, a preferred third embodiment 300 of the power transmission mechanism according to the present invention will be described with reference to the accompanying drawings. FIG. 6 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 300 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member in the said Embodiment 1 and 2, and the description is abbreviate | omitted.
[0041]
  The power transmission mechanism 300 according to the present embodiment includes an opening / closing device 320 including a high-pressure relief valve 322 with a release mechanism having a structure different from that of the high-pressure relief valve 222 in the second embodiment.
[0042]
  FIG. 7 shows a longitudinal sectional view of a high-pressure relief valve 322 with a release mechanism in the present embodiment. As shown in FIG. 7, the high-pressure relief valve 322 with a release mechanism has a valve seat 323b in which a first communication hole 323a communicating with the first bypass line 121a is formed at one end and the other end is A closed hollow valve housing 323 has a head portion 324a that separates the hollow portion of the valve housing 323 into a first oil chamber 323c and a second oil chamber 323d at one end, and the other end is outside the valve housing. A piston 324 extending in the direction, a valve main body 325 disposed in the first oil chamber 323c, a first biasing member 326 that presses the valve main body 325 toward the valve seat 323b, and the second And a second urging member 327 disposed in the oil chamber 323d.
[0043]
  Further, the valve housing 323 is formed with a second communication hole 323e that communicates the first oil chamber 323c and the second bypass line 121b.
  The link device 130 is connected to the other end of the piston 324.
[0044]
  The opening / closing device 320 having such a configuration operates as follows. That is, when both the first and second brake devices 50a and 50b are not operated, or when only one of the first and second brake devices 50a and 50b is operated, the link device 130 is the opening / closing device. No effect on 320. Therefore, in this state, the opening / closing device 320 normally blocks between the pair of hydraulic lines 33, and the hydraulic pressure of the high-pressure side line of the pair of hydraulic lines 33 is the first biasing member. When a predetermined value defined by the urging force 326 is exceeded, the pair of hydraulic lines 33 are communicated with each other.
[0045]
  On the other hand, at the time of brake braking in which both the first and second brake devices 50a and 50b are activated, the link device 130 opposes the piston 324 against the biasing force of the second biasing member 327 and the other end portion. To the side (left side in FIG. 7). Thereby, the pressing force to the valve seat 323b of the valve main body 325 by the first urging member 326 is released, and the first and second bypass lines 121a and 121b are communicated.
[0046]
  Also in the power transmission mechanism 300 provided with such an opening / closing device 320, the same effect as in the second embodiment can be obtained.
[0047]
Embodiment 4 FIG.
  Hereinafter, a power transmission mechanism according to a fourth embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 8 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 400 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member as the said Embodiment 1-3, and the description is abbreviate | omitted.
[0048]
  As shown in FIG. 8, the power transmission mechanism 400 according to the present embodiment includes a hydraulic turn brake device 50 ′.
[0049]
  The hydraulic brake device 50 ′ includes first and second operation members 51a ′ and 51b ′ and first and second hydraulic brake members 52a ′ and 52b provided on the pair of drive axles 22a and 22b, respectively. And a hydraulic mechanism 53 ′ that operates the first and second hydraulic brake members 52 a ′ and 52 b ′ in response to the operation of the first and second operation members 51 a ′ and 51 b ′.
[0050]
  The hydraulic mechanism 53 ′ includes a reserve tank 54 ′, an open line 55 ′ whose base end portion communicates with the reserve tank 54 ′, and first and second communication branches from the distal end portion of the open line 55 ′. Lines 56a ', 56b', first and second master cylinders 57a ', 57b' in which the tip ends of the first and second communication lines 56a ', 56b' are communicated, and the first and second master cylinders 57a ', 57b' and first and second hydraulic brake members 52a ', 52b' communicating with the first and second hydraulic oil lines 58a ', 58b' and the first and second communication lines 56a, respectively. The first and second on-off valves 59a 'and 59b' are respectively inserted in ', 56b'.
[0051]
  The first and second master cylinders 57a ′ and 57b ′ include first and second housings 151a ′ and 151b ′, and first and second chambers in the first and second housings 151a ′ and 151b ′, respectively. First and second pistons 153a ′ and 153b ′ slidably disposed in the first and second housings 151a ′ and 151b ′ so as to form 152a ′ and 152b ′, respectively, And first and second urging members 154a ′ and 154b ′ disposed in the second chambers 152a ′ and 152b ′, respectively.
[0052]
  The first piston 153a ′ and the first opening / closing valve 59a ′ are operatively connected to the first operating member 51a ′, and the second piston 153b ′ and the second opening / closing valve 59b ′ are connected to the first operating member 51a ′. 2 is operatively connected to the operating member 51b '. That is, when the first operating member 51a ′ is operated, the first on-off valve 59a ′ is pushed so as to block the first communication line 56a ′, and the volume of the first chamber 152a ′ is reduced. Further, the first piston 153a ′ is pushed against the biasing force of the first biasing member 154a ′. Similarly, when the second operation member 51b ′ is operated, the second on-off valve 59b ′ is pushed so as to block the second communication line 56b ′, and the volume of the second chamber 152b ′ is reduced. Thus, the second piston 153b ′ is pushed against the urging force of the second urging member 154b ′.
[0053]
  The brake device having such a configuration operates as follows. That is, for example, when the first operating member 51a ′ is operated, the first on-off valve 59a ′ blocks the first communication line 56a ′. As a result, the first hydraulic oil line 58a ′ and the first chamber 152a ′ are closed. Meanwhile, the first piston 153a ′ reduces the volume of the first chamber 152a ′ by operating the first operation member 51a ′. Accordingly, the volume of the first hydraulic oil line 58a ′ and the first chamber 152a ′ is reduced while being closed. Accordingly, the hydraulic pressure of the first hydraulic oil line 58a ′ is increased, and the first brake member 52a ′ is operated by the increase of the hydraulic pressure, and the rotation of the corresponding drive axle 22a is stopped.
[0054]
  The power transmission mechanism 400 provided with such a hydraulic brake device 50 ′, instead of the release mechanism 110 in the first to third embodiments, corresponds to the planetary gear according to the braking operation of the hydraulic turn brake device 50 ′. A release mechanism 410 for freeing the first element of the device 40 is provided.
[0055]
  The release mechanism 410 according to the present embodiment is disposed between the pair of hydraulic lines 33 in the HST, and an opening / closing device 420 for communicating / blocking the pair of hydraulic lines 33 and braking of the hydraulic turn brake device 50 ′. And a hydraulic link device 430 for operating the opening / closing device 420 according to the operation.
[0056]
  The opening / closing device 420 includes a switching valve 422 that is operated by the action of hydraulic pressure. FIG. 9 shows a longitudinal sectional view of the switching valve 422. The switching valve 422 is substantially the same as the switching valve 122 in the first embodiment except that the switching valve 422 is configured to be operated by the action of hydraulic pressure. That is, the switching valve 422 shuts off the first and second bypass lines 121a and 121b when not receiving the action of hydraulic pressure, and connects both bypass lines 121a and 122b when receiving the action of hydraulic pressure. It is configured.
[0057]
  The hydraulic link device 430 includes first and second branch lines 431a and 431b branched from the first and second hydraulic oil lines 58a ′ and 58b ′, and the first and second branch lines 431a and 431b. And a supply line 433 communicating between the shuttle valve 432 and the switching valve 422.
[0058]
  The shuttle valve 432 communicates with the first and second branch lines 431a and 431b and the supply line 433 according to the hydraulic pressure difference between the first and second branch lines 431a and 431b, The first and second branch lines 431a and 431b and the supply line 433 are disconnected from each other.
[0059]
  Specifically, the shuttle valve 432 includes a communication part 435c formed with an oil passage for communicating the first and second branch lines 431a and 431b with the supply line 433, and both sides of the communication part 435c. The main body 435 includes first and second blocking portions 435a and 435b that are disposed and block the first and second branch lines 431a and 431b and the supply line 433.
[0060]
  The shuttle valve 432 is further disposed on both sides of the main body 435, and the first and second urging members 436a and 436b having the same urging force that presses the main body 435 toward one side and the other side. And communicated with the first branch line 431a, communicated with the first branch chamber 437a for pressing the main body 435 to one side based on the hydraulic pressure of the first branch line 431a, and the second branch line 431b, And a second hydraulic chamber 437b for pressing the main body 435 to the other side based on the hydraulic pressure of the second branch line 431b.
[0061]
  Hereinafter, regarding the operation of the hydraulic link device 430 configured as described above, (i) when both the first and second brake devices 50a ′ and 50b ′ are not operated, (ii) the first and second brakes An example will be described in which only one of the devices 50a ′ and 50b ′ is operated, and (iii) both the first and second brake devices 50a ′ and 50b ′ are operated.
[0062]
(i) When not operating both the first and second brake devices 50a 'and 50b'
  When both the first and second operation members 51a ′ and 51b ′ are not operated, the first and second hydraulic oil lines 58a ′ and 58b ′ are both communicated with the reserve tank 54 ′. . Accordingly, the hydraulic pressures of the first hydraulic oil line 58a ′ (first branch line 431a) and the second hydraulic oil line 58b ′ (second branch line 431b) do not increase.
[0063]
  At this time, since no hydraulic pressure difference is generated between the first and second branch lines 431a and 431b, the shuttle valve 432 is brought into a communication state. However, since the hydraulic pressure of the first and second branch lines 431a and 431b does not increase as described above, the switching valve 422 does not connect the first and second bypass lines 121a and 121b.
  As described above, the hydraulic link device 430 maintains the switching device 420 in the shut-off state when both the first and second brake devices 50a ′ and 50b ′ are not operated.
[0064]
(ii) When only one of the first and second brake devices 50a ′ and 50b ′ is operated
  For example, when only the first brake device 50a ′ is operated in order to make the vehicle turn right or left suddenly, the vehicle operates as follows. That is, according to the operation of the first operating member 51a ′, the first on-off valve 59a ′ blocks the first communication line 56a ′. As a result, the first hydraulic oil line 58a ′ and the first chamber 152a ′ are closed. Further, the operation of the first operating member 51a ′ reduces the volume of the first chamber 152a ′ via the first piston 153a ′. That is, the volume of the first hydraulic oil line 58a ′ and the first chamber 152a ′ is reduced while being closed. Accordingly, the hydraulic pressure of the first hydraulic oil line 58a ′ increases, and the first brake member 52a ′ operates.
[0065]
  On the other hand, since the second hydraulic oil line 58b ′ remains in communication with the reserve tank 54 ′, the hydraulic pressure of the second hydraulic oil line 58b ′ does not increase.
  Thus, when only one of the first and second brake devices 50a ′ and 50b ′ is operated, the first branch line 431a communicated with the first hydraulic oil line 58a ′ and the first A hydraulic pressure difference is generated between the second branch line 431b and the second hydraulic oil line 58b ′.
[0066]
  The shuttle valve 432 is shut off due to the hydraulic pressure difference between the first and second branch lines 431a and 431b. Accordingly, the switching valve 422 maintains the first and second bypass lines 121a and 121b in a shut-off state.
  As described above, when only one of the first and second brake devices 50a ′ and 50b ′ is operated, the hydraulic link device 430 maintains the opening / closing device 420 in a shut-off state.
[0067]
(iii) When both the first and second brake devices 50a ′ and 50 ′ are operated
  When both the first and second operating members 51a ′ and 51b ′ are operated, the hydraulic pressures of the first and second hydraulic oil lines 58a ′ and 58b ′ are both increased. Accordingly, the hydraulic pressures of the first branch line 431a communicated with the first hydraulic oil line 58a ′ and the second branch line 431b communicated with the second hydraulic oil line 58b ′ increase in an equal state.
[0068]
  As described above, when there is no hydraulic pressure difference between the first and second branch lines 431a and 431b, the shuttle valve 432 connects the first and second branch lines 431a and 431b and the supply line 433. Communicate. Accordingly, the hydraulic pressure of the supply line 433 also increases.
[0069]
  The switching valve 422 causes the first and second bypass lines 121a and 121b to communicate with each other by increasing the hydraulic pressure of the supply line 433.
  As described above, the hydraulic link device 430 brings the opening / closing device 420 into a communication state in accordance with a brake braking operation in which both the first and second brake devices 50a ′ and 50b ′ are operated.
[0070]
  As described above, also in the present embodiment, as in the first embodiment, the first element of the planetary gear device 40 can be brought into a free state in accordance with the braking operation of the brake device. Therefore, when it is desired to stop the rotation of the HMT, the HMT can be made to be non-output, and it is possible to effectively prevent an increase in cost due to excessive wear of the brake device and an increase in capacity, and movement contrary to the intention of the vehicle.
[0071]
Embodiment 5 FIG.
  Hereinafter, a preferred fifth embodiment of the power transmission mechanism according to the present invention will be described with reference to the accompanying drawings. FIG. 10 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 500 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member in the said Embodiment 1-4, and the description is abbreviate | omitted.
[0072]
  The power transmission mechanism 500 according to the present embodiment has an opening / closing device 520 provided with a high-pressure relief valve 522 with a release mechanism instead of the opening / closing device 420 provided with the switching valve 422 in the fourth embodiment. Yes.
[0073]
  FIG. 11 is a longitudinal sectional view of the high-pressure relief valve 522 with a release mechanism. As shown in FIG. 11, the high-pressure relief valve 522 has substantially the same configuration as the high-pressure relief valve 222 in the second embodiment except that it is actuated by the action of hydraulic pressure.
  In the present embodiment, the same effect as in the second embodiment can be obtained.
[0074]
Embodiment 6 FIG.
  The sixth preferred embodiment of the power transmission mechanism according to the present invention will be described below with reference to the accompanying drawings. FIG. 12 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 600 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member as in the said Embodiments 1-5, and the description is abbreviate | omitted.
[0075]
  The power transmission mechanism 600 according to the present embodiment uses an opening / closing device 620 provided with a high-pressure relief valve 622 with a release mechanism having a structure different from that of the high-pressure relief valve 522 in the fifth embodiment.
[0076]
  FIG. 13 shows a longitudinal sectional view of the high-pressure relief valve 622 with a release mechanism in the present embodiment. As shown in FIG. 13, the high-pressure relief valve 622 has substantially the same configuration as the high-pressure relief valve 322 in the third embodiment except that the high-pressure relief valve 622 is operated by the action of hydraulic pressure.
  Also in this embodiment, the same effect as in the second or third embodiment can be obtained.
[0077]
Embodiment 7 FIG.
  The seventh preferred embodiment of the power transmission mechanism according to the present invention will be described below with reference to the accompanying drawings. FIG. 14 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 700 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member as in the said Embodiments 1-6, and the description is abbreviate | omitted.
[0078]
  The power transmission mechanism according to the present embodiment includes a release mechanism 710 provided with a clutch device 720 instead of the release mechanism 110 provided with the opening / closing device 120 in the first embodiment.
[0079]
  As shown in FIG. 14, the clutch device 720 is inserted between the HST output shaft 30 b and the sun gear 41 of the planetary gear device 40, and the HST is changed according to the braking operation of the brake device 50. The power transmission between the output shaft 30b and the sun gear 41 can be cut off.
[0080]
  Also in this embodiment, as in the first embodiment, the first element of the planetary gear device 40 can be brought into a free state in accordance with the braking operation of the brake device 50. Therefore, when it is desired to stop the rotation of the HMT, the HMT can be made to be non-output, and it is possible to effectively prevent an increase in cost due to excessive wear of the brake device and an increase in capacity, and movement contrary to the intention of the vehicle.
[0081]
Embodiment 8 FIG.
  Hereinafter, an eighth preferred embodiment of the power transmission mechanism according to the present invention will be described with reference to the accompanying drawings. FIG. 15 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 800 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member in the said Embodiment 1-7, and the description is abbreviate | omitted.
[0082]
  In the first to seventh embodiments, the sun in the planetary gear device 40 depends on the braking operation of the brake device 50 (in the case of a turn brake device, the operation of both the first and second brake devices 50a and 50b). Although the gear 41 is configured to be in a free state, the present embodiment is configured to cause the planetary carrier 43 to be in a free state in accordance with the braking operation of the brake device 50.
[0083]
  That is, in the power transmission mechanism 800 according to the present embodiment, instead of the release mechanism in each of the above embodiments, the drive source 10 to the planetary carrier 43 in the planetary gear device 40 according to the braking operation of the brake device 50. A release mechanism 810 having a clutch device 820 for interrupting power transmission is provided.
[0084]
  The clutch device 820 can be disposed at various positions on the transmission path from the drive source 10 to the planet carrier 43. For example, as shown in FIG. 15, a clutch device is incorporated in a flywheel 90 ′ inserted between the drive source 10 and the HST input shaft 30a, or as shown in FIG. The drive shaft 60 can be provided with a clutch device 820 ′ that interrupts power transmission between the PTO drive shaft 60 and the planet carrier 43.
[0085]
  According to the configuration shown in FIG. 16, the rotation of the PTO drive shaft 60 can be maintained while the planetary gear device 40 is in a non-output state during braking.
[0086]
Embodiment 9 FIG.
  The ninth preferred embodiment of the power transmission mechanism according to the present invention will be described below with reference to the accompanying drawings. FIG. 17 is a schematic diagram showing a hydraulic circuit in a main part of the power transmission mechanism 900 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent member in the said Embodiment 1-8, and the description is abbreviate | omitted.
[0087]
  In the first to eighth embodiments, as described above, one of the input side elements in the planetary gear device 40 is set in a free state in accordance with the braking operation of the brake device. In the embodiment, the power transmission between the output side element of the planetary gear device 40 and the drive wheel 20 can be interrupted according to the braking operation of the brake device 50.
[0088]
  That is, the power transmission mechanism 900 according to the present embodiment includes a release mechanism 910 instead of the release mechanism 110 in the first embodiment.
  The release mechanism 910 is interposed between the internal gear 44 acting as an output side element of the planetary gear device 40 and the drive wheel 20 and is driven from the planetary gear device 40 in accordance with the braking operation of the brake device 50. A clutch device 920 configured to cut off power transmission to the wheels 20 is provided. In the present embodiment, the clutch device 920 is disposed between the internal gear 44 and the forward / reverse switching clutch device 65.
[0089]
  With such a power transmission mechanism 900, the following effects can be obtained. That is, in this embodiment, even when the HST swash plate is tilted to a theoretical tilt angle at which the HMT output shaft is in a non-rotating state, the HMT output shaft may be rotated. . However, in the present embodiment, a clutch device 920 that cuts off power transmission from the HMT output side element (internal gear 44) to the drive wheel 20 according to the braking operation of the brake device 50 is provided. Therefore, when the brake device 50 is braked to stop the vehicle (in the case of a turn brake device, both the first and second brake devices 50a and 50b are operated), the drive axle is unexpectedly driven. No driving force is transmitted from the HMT to 22. Accordingly, as in the above-described embodiments, it is possible to effectively prevent inconveniences such as excessive wear of the brake device and an increase in cost due to an increase in capacity and movement contrary to the intention of the vehicle.
[0090]
【The invention's effect】
  Power transmission according to the present inventionIndeedAccording to HSTas well asPlanetary gear setConsist ofHMTA differential device that differentially transmits the driving force from the HMT to a pair of left and right drive wheels, and a pair of first and second brake devices that individually apply a braking force to the pair of drive wheels, respectivelyOf the planetary gear setFirstEquipped with a release mechanism to put theThe release mechanism is a switching valve for communicating or blocking between the pair of hydraulic lines, the switching valve being biased toward the blocking position by a biasing member, and a mechanical link for operating the switching valve A first connecting rod having one end rotatably connected to a swing arm for operating the first brake device, and one end operating the second brake device. A second connecting rod rotatably connected to the swinging arm, a common rod rotatably connected to the other ends of the first and second connecting rods, and movement of the common rod in the longitudinal axis direction And a link mechanism that positions the switching valve at the communication position against the urging force of the urging member, and the longitudinal axes of the first and second connecting rods are the longitudinal axes of the common rods. In contrast, they are arranged so as to be inclined at substantially the same angle in opposite directions. It is, configured so that the common rod moves longitudinally only when both of said first and second brake device is actuatedBecauseWhen only one of the first and second brake devices is operated, such as when the vehicle is turning sharply, both the first and second brake devices are operated while outputting the driving force from the HMT. TheIf you want to stop the vehicleIsThe HMT output shaft can be made non-rotating. Accordingly, it is possible to effectively prevent an increase in cost due to excessive wear of the brake device and an increase in capacity, and movement contrary to the intention of the vehicle.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a transmission structure of a vehicle provided with Embodiment 1 of a power transmission mechanism according to the present invention.
FIG. 2 is a hydraulic circuit diagram of a main part of the power transmission mechanism according to the first embodiment.
3 is a longitudinal sectional view of a switching valve in the power transmission mechanism shown in FIGS. 1 and 2. FIG.
FIG. 4 is a principal hydraulic circuit diagram of Embodiment 2 of the power transmission mechanism according to the present invention.
FIG. 5 is a longitudinal sectional view of a high pressure relief valve with a release mechanism in the power transmission mechanism shown in FIG. 4;
FIG. 6 is a principal hydraulic circuit diagram of Embodiment 3 of the power transmission mechanism according to the present invention.
7 is a longitudinal sectional view of a high-pressure relief valve with a release mechanism in the power transmission mechanism shown in FIG.
FIG. 8 is a main part hydraulic circuit diagram of a power transmission mechanism according to a fourth embodiment of the present invention.
9 is a longitudinal sectional view of a switching valve in the power transmission mechanism shown in FIG. 8. FIG.
FIG. 10 is a principal hydraulic circuit diagram of Embodiment 5 of the power transmission mechanism according to the present invention.
FIG. 11 is a longitudinal sectional view of a high pressure relief valve with a release mechanism in the power transmission mechanism shown in FIG. 10;
FIG. 12 is a main part hydraulic circuit diagram of Embodiment 6 of the power transmission mechanism according to the present invention;
13 is a longitudinal sectional view of a high-pressure relief valve with a release mechanism in the power transmission mechanism shown in FIG.
FIG. 14 is a main part hydraulic circuit diagram of Embodiment 7 of the power transmission mechanism according to the present invention;
FIG. 15 is a main part hydraulic circuit diagram of Embodiment 8 of the power transmission mechanism according to the present invention;
FIG. 16 is a main part hydraulic circuit diagram of Embodiment 9 of the power transmission mechanism according to the present invention;
FIG. 17 is a main part hydraulic circuit diagram of a modification of the power transmission mechanism shown in FIG. 16;
FIG. 18 is a schematic diagram showing theoretical operation characteristics of HMT.
[Explanation of symbols]
10 Drive source
20 Drive wheels
21      Differential
30 HST
30a HST input shaft (pump shaft)
30b HST output shaft (motor shaft)
31 Hydraulic pump
32 Hydraulic motor
40 planetary gear set
41 Sun Gear
43 Planetary Carrier
44 Internal gear
50a    FirstBrake device
50b    Second brake device
53a    Swing arm of the first brake device
53b    Swing arm of the second brake device
100 Power transmission mechanism
110    Release mechanism
122    Switching valve
130    Mechanical link device
131a  1st connecting rod
131b  Second connecting rod
132    Common bar
140    Link mechanism

Claims (2)

A power transmission mechanism for a vehicle that transmits driving force from a driving source to a pair of left and right driving wheels,
A hydrostatic continuously variable transmission that has a hydraulic pump, a hydraulic motor, and a pair of hydraulic lines that fluidly connect both of them, and that outputs the rotational driving force from the drive source by continuously shifting;
A sun gear, a planetary carrier, and an internal gear, and an output from the hydrostatic continuously variable transmission is input to a first element of the three elements; A planetary gear set configured to be able to extract a variable speed driving force from two elements;
A differential device that differentially branches the driving force from the planetary gear device to the pair of drive wheels;
A pair of first and second brake devices for individually applying braking force to the pair of drive wheels ,
Before SL and a release mechanism that obtained by the free state the first element of the planetary gear unit,
The release mechanism is a switching valve for communicating or blocking between the pair of hydraulic lines, the switching valve being biased toward a blocking position by a biasing member, and a mechanical link device for operating the switching valve And
The mechanical link device has a first connecting rod rotatably connected to a swing arm for operating the first brake device at one end, and a swing arm for operating the second brake device at one end. A second connecting rod that is freely connected; a common rod in which the other ends of the first and second connecting rods are rotatably connected; and the biasing in response to movement of the common rod in the longitudinal axis direction. A link mechanism for positioning the switching valve at a communication position against the biasing force of the member,
The first and second connecting rods are arranged such that their respective longitudinal axes are inclined at substantially equal angles to each other in opposite directions with respect to the longitudinal axis of the common rod, and both the first and second brake devices are arranged. The power transmission mechanism is characterized in that the common bar moves in the longitudinal axis direction only when the is operated . The switching valve is a high-pressure relief valve that causes one hydraulic fluid line to communicate with the other hydraulic fluid line when the hydraulic pressure of one hydraulic fluid line of the pair of hydraulic fluid lines exceeds a predetermined pressure. The power transmission mechanism according to claim 1, wherein:

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