JP4003393B2 - Driving force transmission device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle driving force transmission device that is disposed between a drive-side rotation shaft and a driven-side rotation shaft of a vehicle and constitutes the vehicle as a four-wheel drive vehicle.
[0002]
[Prior art]
  This type of vehicle driving force transmission device includes a rotation shaft on the drive side and a rotation shaft on the driven side of the vehicle.ofInner and outer rotating members that are connected to each other and are coaxially and relatively rotatable with each other, and friction engagement between these rotating members.ByA friction clutch that transmits torque between the rotating members, and a pressing force generating mechanism that generates a pressing force to frictionally engage the friction clutch according to the differential rotation of the rotating members. Examples are disclosed in, for example, Japanese Patent Application Laid-Open No. 10-141395 and Japanese Patent No. 2884473. Among these publications, the driving force transmission device disclosed in the former publication is of the rotor type, and the driving force transmission device disclosed in the latter publication is of the shear pump type.
[0003]
[Problems to be solved by the invention]
By the way, the driving force transmission device of this type is required to respond according to the running state of the vehicle. However, each of the driving force transmission devices described above is a differential that depends only on the differential rotational speed between the front and rear wheels. Since it is configured to be rotation sensitive, even when the vehicle is traveling at high speed, if a differential rotation occurs between the front and rear wheels, a four-wheel drive state is configured accordingly. When the vehicle is traveling at a high speed, the vehicle is not necessarily required to travel four-wheels, and a high-speed four-wheel drive traveling consumes wasted energy, thereby reducing fuel consumption.
[0004]
Accordingly, an object of the present invention is to eliminate wasteful energy consumption by configuring a vehicle driving force transmission device of this type in a vehicle speed sensitive type that cannot form a four-wheel drive state when the vehicle is traveling at high speed. This is to improve fuel economy.
[0005]
[Means for Solving the Problems]
  The present invention relates to a vehicle driving force transmission device that is disposed between a drive-side rotation shaft and a driven-side rotation shaft of a vehicle and constitutes a four-wheel drive vehicle.ofAn inner and outer rotating members that are connected to each other and are coaxially and relatively rotatable, a friction clutch that is disposed between the rotating members and transmits torque between the rotating members by friction engagement; A pressing force generating mechanism for generating a pressing force for frictionally engaging the clutch in accordance with the differential rotation of the rotating members;And the pressing force generation mechanism includes a pressing force generation control means for reducing or regulating the generation of the pressing force when the vehicle speed is higher than a predetermined speed.The vehicle driving force transmission device of the type provided is applied.
[0006]
  Thus, in the first vehicle driving force transmission according to the present invention, the pressing force generating mechanism is positioned in the viscous fluid accommodating space and is relatively rotated by the differential rotation of the inner and outer rotating members and pushed. A rotor-type pressing force generation mechanism including a rotor for generating pressure, and the pressing force generation control means includes a valve mechanism provided in the housing space.It is to be prepared.
[0007]
  First vehicle driving force transmission device according to the present inventionThe valve mechanism closes a part or all of a communication hole provided at a base end part of the vane part of the rotor and communicating adjacent pressure generating chambers with each other, and an opening part of the communication hole. The valve body is configured to generate a pressing force, and the valve body is configured to flow a viscous fluid that flows toward the vane portion that is generated in the pressure generation chamber by relatively rotating in the housing space when the rotor is differentially rotated. The opening part of the communication hole of the vane part is pressed by the action to close the opening part of the communication hole, and along the one side of the vane part by the action of centrifugal force generated when the vehicle speed is higher than a predetermined speed. It is configured to move to the distal end side and open the opening of the communication hole.
[0008]
  Further, in the second vehicle driving force transmission device according to the present invention, the pressing force generating mechanism has a circumferential groove for allowing the viscous fluid to flow, and is relatively rotated by the differential rotation of the inner and outer rotating members. A pressing force generating mechanism of a shear pump type having a pump disk for generating a pressing force, and the pressing force generation control means includes a valve mechanism provided in the circumferential groove.It is to be prepared.
[0009]
  Second vehicle driving force transmission device according to the present inventionInThe aboveThe valve mechanism is provided at the base end portion of the both-end blocking portion of the circumferential groove and closes a part or all of the communication passage that communicates the both ends of the circumferential groove with each other. The valve body generates the pressing force, and the valve body is the same by the fluid action of the viscous fluid that flows to the both-end closed portion side that is generated in the circular groove when the pump disk is differentially rotated. By pressing the opening side of the communicating hole of the closed end of both ends to close the opening of the communicating hole, the tip along one side of the closed end of the both ends by the action of centrifugal force generated when the vehicle speed is higher than a predetermined speed It is configured to move to the side and open the opening of the communication hole.
[0010]
[Operation and effect of the invention]
In the vehicle driving force transmission device according to the present invention, the pressing force generation mechanism is provided with pressing force generation control means for reducing or restricting the generation of pressing force when the vehicle speed is higher than a predetermined speed. When the vehicle is in a high-speed running state or when the vehicle is moving from low-speed driving to high-speed driving, the pressing force generated by the pressing force generation mechanism responds to the vehicle speed. Gradually decreases or disappears. For this reason, when the vehicle does not require four-wheel drive traveling, the transmission torque that constitutes the four-wheel drive traveling state of the vehicle decreases or disappears, preventing unnecessary energy consumption and improving fuel efficiency. Can be planned.
[0011]
In the vehicle driving force transmission device according to the present invention, a rotor-type pressing force generation mechanism and a shear pump-type pressing force generation mechanism can be employed as the pressing force generation mechanism.
[0012]
When the pressing force generation mechanism is a rotor-type pressing force generation mechanism, the pressing force generation control means operates adjacent to each other when the vehicle speed is higher than a predetermined level and is partitioned by the vane portion of the rotor. The pressure generating chamber is configured as a valve mechanism that functions to communicate with each other, and the valve mechanism is provided in the vane portion of the rotor and communicates with the adjacent pressure generating chambers, and the opening of the communication hole. It can be configured by a valve body that closes part or all of the part and opens the opening part by centrifugal force generated when the vehicle speed is higher than a predetermined speed. Accordingly, there is a great advantage that the pressing force generation control means can be configured with a simple structure and the pressing force generated by the pressing force generation mechanism can be accurately controlled.
[0013]
  Further, the pressing force generating mechanism isShear pump typeWhen the vehicle speed is higher than a predetermined speed, the pressing force generation control means isInThe valve mechanism is configured to operate and function to communicate the both ends of the circumferential groove with each other. The valve body can be configured by closing a part or all of the opening and opening the opening by a centrifugal force generated when the vehicle speed is higher than a predetermined speed. Thus, the pressing force generation control means can be configured with a simple structure, and there is a great advantage that the pressing force generated by the pressing force generation mechanism can be accurately controlled.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 shows a vehicle driving force transmission device according to an example of the present invention. As shown in FIG. 6, the driving force transmission device 10 is mounted on a driving force transmission path to the rear wheel side of the vehicle based on the front wheel drive to constitute a four-wheel drive vehicle.
[0015]
In the four-wheel drive vehicle, the torsion axle 21 is integrally provided with a transmission, a transfer, and a front differential, and the driving force of the engine 22 is output to both axle shafts 24 a and 24 a via the front differential 23 of the transaxle 21. Then, the left and right front wheels 24b, 24b are driven and output to the first propeller shaft 25 side. The first propeller shaft 25 is connected to the second propeller shaft 26 via the driving force transmission device 10. When the first propeller shaft 25 and the second propeller shaft 26 are connected so as to transmit torque, the first propeller shaft 25 is driven. The force is transmitted to the rear differential 27 and is output from the rear differential 27 to both axle shafts 28a and 28a to drive the left and right rear wheels 28b and 28b.
[0016]
The driving force transmission device 10 includes a rotor-type pressing force generation mechanism, and is disposed between a first propeller shaft 25 (drive-side rotating shaft) and a second propeller shaft 26 (driven-side rotating shaft). As shown in FIG. 1, an outer case 10a, an inner shaft 10b, a friction clutch 10c, and a pressing force generation mechanism 10d are provided, and a valve mechanism 10e shown in FIGS. 2 and 3 is provided.
[0017]
The outer case 10a corresponds to the outer rotating member in the present invention, and includes a bottomed cylindrical front housing 11a and a rear cover 11b that is screwed into the rear end opening of the front housing 11a and covers the opening. Is formed. The rear cover 11b also functions as a component member that constitutes a housing space portion of a pressing force generation mechanism 10d described later. The inner shaft 10b penetrates the central portion of the rear cover 11b in a liquid-tight manner and is concentrically inserted into the front housing 11a, and the front wall portion of the front housing 11a and the rear cover 11b are axially restricted. Is rotatably supported. The tip of the second propeller shaft 26 is inserted into the inner shaft 10b so as to be able to transmit torque. The first propeller shaft 25 is connected to the front end of the front housing 11a of the outer case 10a. Are connected so that torque can be transmitted.
[0018]
The friction clutch 10c is a wet multi-plate clutch, and includes a large number of clutch plates (an inner clutch plate 12a and an outer clutch plate 12b), and is disposed in the front housing 11a. Each inner clutch plate 12a constituting the friction latch 10c is assembled to the outer periphery of the inner shaft 10b by spline fitting so as to be movable in the axial direction, and each outer clutch plate 12b is splined to the inner periphery of the front housing 11a. It is assembled so that it can be fitted and moved in the axial direction. The inner clutch plates 12a and the outer clutch plates 12b are alternately positioned, abut against each other and frictionally engage with each other, and are separated from each other to be in a free state. The friction clutch 10c transmits torque according to the frictional engagement force between the outer case 10a and the inner shaft 10b by frictional engagement between the inner clutch plates 12a and the outer clutch plates 12b.
[0019]
The pressing force generation mechanism 10d is disposed between the outer case 10a and the inner shaft 10b so as to be opposed to the friction clutch 10c. The rear cover 11b, the rotor 13, the working piston 14, the rear cover 11b, and the working piston 14 are arranged. The storage space R configured as described above and the viscous fluid stored in the storage space R are provided with a valve mechanism 10e in the storage space R of the viscous fluid.
[0020]
The operating piston 14 has a circular recess on the back, and is positioned between the front housing 11a and the inner shaft 10b. The front housing 11a is spline-fitted to the inner periphery thereof and axially moved. The inner shaft 10b is assembled so as to be movable, and is rotatably assembled to the outer periphery of the inner shaft 10b so as to be movable in the axial direction. In this state, the working piston 14 together with the rear cover 11b
The circular recess is formed in the accommodation space R in which the viscous fluid is accommodated. The rotor 13 is spline-fitted to the outer periphery of the inner shaft 10b, and is positioned in the accommodating space R in a state where it is assembled so as to be integrally rotatable with the inner shaft 10b.
[0021]
As shown in FIGS. 1 to 3, the rotor 13 has four vane portions 13 b on the outer periphery of a cylindrical support shaft portion 13 a having an inner spline portion, and is assembled in the accommodation space portion R. In the state, the accommodation space R is divided into four pressure generation chambers r. Each vane portion 13b has a communication hole 13c in the base end side portion thereof that allows adjacent pressure generation chambers r to communicate with each other. The front end portion of the communication hole 13c has a substantially inverted T-shaped thick portion 13b1, and the front portion of the thick portion 13b1 is replaced by a wide thin portion 13b2, and the rear portion of the thick portion 13b1. The portion is a narrow thin portion 13b3. The communication hole 13c of the rotor 13 constitutes a valve mechanism 10e described later. Further, the thick portion 13b1 of the rotor 13 includes an inner surface of the recess of the working piston 14 forming the housing space portion R, and an inner surface of the rear cover 11b, that is, two inner surfaces of the housing space portion R facing each other ( The two opposing surfaces) and can slide relative to the two opposing surfaces.
[0022]
The valve mechanism 10e is configured by a communication hole 13c of each of the two vane portions 13b at a symmetrical position of the rotor 13 and a valve body 15 disposed in the two pressure generating chambers r at a symmetrical position. ing. The valve body 15 has a disk shape having substantially the same thickness as the thick portion 13b1 of the vane portion 13b, and the communication hole 13c is formed in the opening portion in contact with the proximal end portion of the vane portion 13b. And function to close.
[0023]
That is, when relative rotation occurs between the outer case 10a and the inner shaft 10b and a flow is generated in the viscous fluid stored in the storage space R, the valve body 15 closes the communication hole 13c. The valve body 15 in the closed state is in contact with two opposing surfaces of the accommodation space R and is slidable with respect to these opposing surfaces. When centrifugal force acts, the vane portion It functions to slide to the tip side of 13b to open the communication hole 13c.
[0024]
The driving force transmission device 10 is mounted on a vehicle and constitutes a four-wheel drive vehicle based on the front wheel drive shown in FIG. 6, and the four-wheel drive vehicle is driven with priority on the front wheels 24b during traveling, When the first propeller shaft 25 is connected to the second propeller shaft 26 so that torque can be transmitted by the driving force transmission device 10, the driving force of the engine 22 is transmitted via the first propeller shaft 25 and the second propeller shaft 26. It is transmitted to the rear wheel 28b side to constitute a four-wheel drive running state.
[0025]
In the driving force transmission device 10, while the vehicle is traveling, the outer case 10 a connected to the first propeller shaft 25 is always rotating and rotates between the inner shaft 10 b connected to the second propeller shaft 26. In other words, in other words, when differential rotation occurs between the front and rear wheels 24a and 24b, the inner shaft 10b and the rotor 13, and the outer case 10a and the working piston 13 rotate relative to each other.
[0026]
As a result, the viscous fluid filled in the pressure generating chamber r is forcibly moved between the two opposing surfaces opposed to each other by the vane portion 13b of the rotor 13 at a flow rate corresponding to the differential rotation speed, and pressure is applied by the viscous friction of the viscous fluid. An internal pressure proportional to the differential rotation speed is generated in the generation chamber r. That is, an internal pressure having a pressure distribution in which the upstream side of the viscous fluid flowing between the two opposed surfaces is high pressure and the downstream side is low pressure is generated, and this internal pressure acts to press the working piston 14.
[0027]
As a result, the operating piston 14 is pushed by the above-described internal pressure, and presses the friction clutch 10c with a force corresponding to the differential rotational speed to frictionally engage the friction clutch 10c. Thereby, the friction clutch 10c connects the inner shaft 10b to the outer case 10a, and transmits torque according to the differential rotational speed to the inner shaft 10b. For this reason, the driving force of the engine 22 is transmitted to the second propeller shaft 26 via the inner shaft 10b, and the vehicle is configured in a four-wheel drive state.
[0028]
Therefore, in the driving force transmission device 10, the valve mechanism 10e disposed in the accommodating space R of the pressing force generating mechanism 10d is shown in FIG. 3 (a) when the traveling speed of the vehicle is less than a predetermined speed. ), And when the traveling speed of the vehicle becomes higher than a predetermined speed, the state shown in FIG.
[0029]
That is, in the driving force transmission device 10, the rotor 13 relatively rotates in the accommodation space R due to the occurrence of differential rotation, and the viscous fluid in the pressure generation chamber r flows toward the valve body 15, so that the valve body 15 Is pressed against the proximal end portion of the vane portion 13b to close the communication hole 13c, but the centrifugal force caused by the traveling of the vehicle acts on the valve body 15. The centrifugal force acts to slide the valve body 15 from the proximal end side portion of the vane portion 13b to the distal end side portion.
[0030]
Therefore, in the driving force transmission device 10, when the traveling speed of the vehicle is less than a predetermined speed, the centrifugal force acting on the valve body 15 is small, and the valve body 15 moves from the proximal end side portion to the distal end side portion. As shown in FIG. 3A, the valve mechanism 10e is seated on the opening end of the communication hole 13c and substantially closes the communication hole 13c. The communication is almost cut off. For this reason, an internal pressure corresponding to the differential rotational speed is generated in the pressure generating chamber r, and the internal pressure frictionally engages the friction clutch 10c via the operating piston 14 to bring the vehicle into a four-wheel drive running state. To do.
[0031]
Further, in the driving force transmission device 10, when the traveling speed of the vehicle becomes equal to or higher than a predetermined speed, the centrifugal force acting on the valve body 15 increases, and the valve body 15 slides from the proximal end side portion to the distal end side portion. As shown in FIG. 3B, the valve mechanism 10e moves away from the opening end portion of the communication hole 13c to open the communication hole 13c, and connects the adjacent pressure generation chambers r to each other. For this reason, the internal pressure generated in the pressure generating chamber r decreases or becomes almost none, the friction engagement of the friction clutch 10c by the operating piston 14 is restricted, and the vehicle is changed from the four-wheel drive running state to the two-wheel drive running state. Change it. Further, even when differential rotation occurs while the vehicle is traveling at high speed, the driving force transmission device 10 does not configure the vehicle to be in a four-wheel drive traveling state.
[0032]
Therefore, in the driving force transmission device 10, when the vehicle is traveling at a high speed where four-wheel drive traveling is not required, the transmission torque constituting the four-wheel drive traveling state of the vehicle is reduced or eliminated, and wasteful energy is consumed. Consumption can be prevented and fuel consumption can be improved.
[0033]
In the driving force transmission device 10, the rotational speed of the front wheel 24b and the rotational speed of the front wheel 24b are different from each other in the differential rotational state where the rotational speed of the front wheel 24b is large and the rotational speed of the rear wheel 28b is small. In the differential rotation state where the rotation speed of the rear wheel 28b is small and the rotation speed of the rear wheel 28b is large (the reverse rotation state of the differential rotation), consideration is given so that the transmission torque differs between the outer case 10a and the inner shaft 10b.
[0034]
That is, in the driving force transmission device 10, when a forward differential rotation occurs between the front wheel 24 b and the rear wheel 28 b, the rotor 13 rotates relative to the clockwise direction shown in FIG. 3. For this reason, the viscous fluid in each pressure generating chamber r is subjected to a large shearing action in the wide thin portion 13b2 of the vane portion 13b, and the internal pressure is increased in each pressure generating chamber r. On the other hand, when a differential rotation in the reverse state occurs between the front wheel 24b and the rear wheel 28b, the rotor 13 rotates relative to the counterclockwise direction shown in FIG. For this reason, the viscous fluid in each pressure generating chamber r is subjected to a small shearing action in the narrow thin portion 13b3 of the vane portion 13b, and the internal pressure generated in each pressure generating chamber r is normal. It becomes smaller compared to the differential rotation of the state.
[0035]
4 and 5 show modifications of the valve mechanism provided in the pressing force generation mechanism 10d of the driving force transmission device 10. The valve mechanisms 10f and 10g according to these modified examples are different from the valve mechanism 10e in the shape of the valve body.
[0036]
The valve body 16 of the valve mechanism 10f shown in FIG. 4 is a block having a shape similar to the vane portion 13b of the rotor 13, and is a meat that comes into contact with the two opposing surfaces of the accommodation space R on both the front and back surfaces of the valve body 16. A thick contact surface 16a and a thin portion 16b having a thickness larger than that of the communication hole 13c are provided. The valve body 16 slides from the proximal end side portion of the vane portion 13b to the distal end side portion due to the action of centrifugal force, and as shown in the figure, the valve body 16 is located at the proximal end side portion of the vane portion 13b. When the opening part of the communication hole 13c of the vane part 13b is partially closed by the two contact surfaces 16a and the thin part 16b and is slid to the tip side part of the vane part 13b, the vane part 13b The opening of the communication hole 13c is completely opened.
[0037]
In the valve body 16, the thin portion 16b has a pressure generating function similar to that of the thin portions 13b2 and 13b3 of the vane portion 13b of the rotor 13, and even if the flow of the viscous fluid to the communication hole 13c is subtracted, the total A high pressure is generated.
[0038]
Accordingly, in the valve mechanism 10f, the maximum set value of the generated pressing force is set larger than that of the valve mechanism 10e, and when the traveling speed of the vehicle exceeds a predetermined speed, the valve mechanism 10e operates in the same manner as the valve mechanism 10e. The same effect is obtained.
[0039]
The valve body 17 constituting the valve mechanism 10g shown in FIG. 5 is a substantially square block, and both front and back surfaces of the valve body 17 are formed on contact surfaces that contact two opposing surfaces of the accommodation space R. ing. The valve body 17 slides from the proximal end side portion of the vane portion 13b to the distal end side portion by the action of centrifugal force, and is located at the proximal end portion of the vane portion 13b as shown in FIG. In other words, when the opening of the communication hole 13c of the vane portion 13b is substantially completely closed and slid to the tip side portion of the vane portion 13b, the opening of the communication hole 13c of the vane portion 13b is completely opened.
[0040]
Accordingly, in the valve mechanism 10g, the maximum set value of the generated pressing force is set larger than that of the valve mechanism 10e, and when the traveling speed of the vehicle exceeds a predetermined speed, the valve mechanism 10e operates in the same manner as the valve mechanism 10e. The same effect is obtained.
[0041]
FIG. 7 shows a vehicle driving force transmission device according to another example of the present invention. The drive force transmission device 30 constitutes a four-wheel drive vehicle based on rear wheel drive, and is a drive force transmission device of a type including a multi-plate friction clutch mechanism and a shear pump type pump mechanism.
[0042]
The driving force transmission device 30 includes a shear pump type pressing force generation mechanism, and a friction clutch mechanism 30a and a pump mechanism 30b are disposed between an outer case 31 and an inner shaft 32 concentrically located in the outer case 31. The pump mechanism 30b corresponds to a pressing force generation mechanism in the present invention, and a valve mechanism 30c shown in FIG. 8 as pressing force generation control means is provided in the pump mechanism 30b.
[0043]
The inner shaft 32 has a cylindrical shape, and includes an inner spline 32b on the peripheral surface of the inner hole of the shaft body 32a, and a rear wheel side propeller shaft that transmits engine driving force to the rear wheel side passes through the inner hole. The spline is fitted in the connected state. Thereby, the inner shaft 32 rotates integrally with the rear wheel side propeller shaft. The outer case 31 has a cylindrical shape larger in diameter than the inner shaft 32 and is concentrically positioned on the outer periphery of the inner shaft 32 with a predetermined circumferential interval. A receiving plate 34b constituting a friction clutch mechanism 30a, which will be described later, is fitted and connected to the outer case 31 at the other end opening side of the inner spline 31a so as to be integrally rotatable. It is connected to the propeller shaft on the front wheel side through a support plate 34b and connecting means (not shown) so that power can be transmitted.
[0044]
The friction clutch mechanism 30a includes a large number of inner clutch plates 33a and outer clutch plates 33b, a pressing plate 34a and a receiving plate 34b, and a connecting member 35. The connecting member 35 has a stepped cylindrical shape, and includes an inner spline 35b on the peripheral surface of the inner hole of the cylindrical main body 35a and an outer spline 35c on the outer peripheral surface of the cylindrical main body 35a. The connecting member 35 is positioned coaxially with the inner shaft 32, and its inner spline 35b is in phase with the inner spline 32b of the inner shaft 32 and is spline-fitted to a rear wheel side propeller shaft (not shown). Thereby, the connecting member 35 is connected to the rear wheel side propeller shaft together with the inner shaft 32 so as to be integrally rotatable.
[0045]
In the friction clutch mechanism 30a, each inner clutch plate 33a is fitted to the outer spline 35c of the connecting member 35, and each outer clutch plate 33b is fitted to the inner spline 31a of the outer case 31, so that the inner clutch plate 33a and the outer clutch plate 33b are alternately positioned. The pressing plate 34a is positioned to face the innermost outer clutch plate 33b. The receiving plate 34b is positioned facing the outermost inner clutch plate 33a in a state where the receiving plate 34b is fitted to the inner spline 31a of the outer case 31 and is secured by the snap ring.
[0046]
The pump mechanism 30 b uses a high-viscosity viscous fluid as a working fluid, and includes a pump disk 36, a feed disk 37, a cover body 38, and a working piston 39. The operating piston 39 has an annular recess 39a on one end face, and is assembled to the outer periphery of the inner shaft 32 so as to be rotatable and slidable in the axial direction, and is opposed in a state of being fitted in the inner hole of the pressing plate 34a. is doing. The pump disk 36 and the feed disk 37 are fitted in the annular recess 39a of the working piston 39, and the feed disk 37 is connected to the outer periphery of the inner shaft 32 so as to be integrally rotatable, and the back of the annular recess 39a. It slidably contacts the wall surface. The pump disk 36 is slidably in contact with one end surface of the feed disk 37 in a state where the pump disk 36 is rotatably assembled to the outer periphery of the inner shaft 32.
[0047]
The cover body 38 is fitted to the outer periphery of the operating piston 39 in a state of being fitted to the circumferential gap between the outer case 31 and the inner shaft 32, and is rotatably assembled to the outer periphery of the inner shaft 32. Further, the cover body 38 is secured by a snap ring at one end side opening of the outer case 31, and the outer case 31 and the pump disk 36 are coupled so as to be integrally rotatable.
[0048]
As shown in FIGS. 7 and 8, the pump disk 36 constituting the pump mechanism 30 b includes a circumferential groove (annular groove 36 a) having a predetermined width opened on one end surface side of the feed disk 37 on the other end surface, and an annular shape. A communication path 36b that communicates both ends of the groove 36a, a hole 36c that is located near each end of the annular groove 36a and functions as a discharge port or an intake port that opens into the annular groove 36a, and a suction port or A hole 36d that functions as a discharge port is provided.
[0049]
A disc-shaped valve element 36e is accommodated in the annular groove 36a. The valve body 36e functions so as to be attached to and detached from each opening end portion of the communication passage 36b to interrupt communication between both ends of the annular groove 36a. The valve body 36e and the communication passage 36b are configured to generate a pressing force in the present invention. The valve mechanism 30c which is a control means is comprised. The valve element 36e in the valve mechanism 30c is a small-diameter disk that is approximately half the groove width of the annular groove 36a, and moves to the outer peripheral wall side of the annular groove 36a when a centrifugal force larger than a predetermined value is applied. To do.
[0050]
The cover body 38 includes an annular recess 38a on one end surface side, and a piston 38b is fitted in the annular recess 38a so as to be slidable in a liquid-tight manner. The piston 38b forms a viscous fluid containing chamber R1 in the annular recess 38a. The cover body 38 includes a suction hole 38c and a discharge hole 38d that allow the annular groove 36a and the storage chamber R1 to communicate with each other via the suction port 36c and the discharge port 36d of the pump disk 36. The suction hole 38c and the discharge hole 38d allow the viscous fluid to flow in the annular groove 36a.
[0051]
In the pump mechanism 30b, the piston 38b is urged to the other end side by the spring member 38e so that the pressure fluctuation in the accommodation chamber R1 is absorbed by the sliding of the piston 38b. Is urged by the spring member 39b, and the returning operation after the operating piston 39 is pushed is smoothly performed.
[0052]
The driving force transmission device 30 is mounted on a vehicle and constitutes a four-wheel drive vehicle based on rear wheel drive, and the four-wheel drive vehicle penetrates the inner shaft 32 of the driving force transmission device 30 when traveling. The rear wheel side propeller shaft rotates to drive the rear wheel with priority. In the driving force transmission device 30, when the vehicle is running, the inner shaft 32 is always rotating, and differential rotation is generated between the outer case 31 and the outer case 31 that is connected to the front wheel side propeller shaft. In this case, relative rotation occurs between the pump disk 36 and the feed disk 37.
[0053]
Accordingly, the viscous fluid in the annular groove 36a of the pump disk 36 flows in the clockwise direction in FIG. 8 from the hole 36d functioning as the suction port toward the hole 36c functioning as the discharge port due to the viscosity. The pressure is increased according to the flow distance on the 36c side. The high pressure of the viscous fluid on the hole 36c side of the discharge port acts on the friction clutch mechanism 30a via the operating piston 39 to be frictionally engaged. As a result, the friction clutch mechanism 30 a connects the outer case 31 to the inner shaft 32, and transmits torque corresponding to the differential rotational speed to the outer case 31. For this reason, the driving force of the engine is transmitted to the front wheel side propeller shaft via the outer case 31, and the driving force transmission device 30 configures the vehicle in a four-wheel drive state.
[0054]
Therefore, in the driving force transmission device 30, when the traveling speed of the vehicle is less than a predetermined speed, the valve body 36e that constitutes the valve mechanism 30c provided in the pump mechanism 30b is an annular shape of the pump disk 36. When the viscous fluid in the groove 36a flows, as shown in FIG. 8, it sits at one end side opening of the communication passage 36b and blocks communication between both ends of the annular groove 36a, thereby functioning as a viscous fluid discharge port. The flow from the hole 36c side to the hole 36d functioning as the suction port is blocked, and pressure acting on the working piston 39 is generated in the viscous fluid. As a result, the vehicle travels on four wheels.
[0055]
In this state, when the traveling speed of the vehicle becomes higher than a predetermined speed, the centrifugal force acting on the valve body 36e becomes larger than a predetermined value, and the centrifugal force causes the valve body 36e to move toward the outer peripheral wall side of the annular groove 36a. It is made to slide and detach | leave from the one end side opening part of the communicating path 36b, and the both ends of the annular groove 36a are connected mutually. For this reason, since the viscous fluid flows from the discharge side hole 36c side to the suction side hole 36d side, the generation of high pressure of the viscous fluid is reduced or restricted.
[0056]
In the driving force transmission device 30, when the differential rotation between the outer case 31 and the inner shaft is reversed, the viscous fluid flows counterclockwise as shown in FIG. In this case, the hole 36c functions as a suction port, the hole 36d functions as a discharge port, and the valve element 36e is seated in the opening on the other end side of the communication passage 36b by making a complete rotation in the annular groove 36a. The communication between both ends of the annular groove 36a is blocked.
[0057]
Therefore, the driving force transmission device 30 changes the vehicle from the four-wheel drive running state to the two-wheel drive running state when the running speed of the vehicle becomes a predetermined speed or higher. As a result, when the vehicle does not require four-wheel drive traveling, the transmission torque that constitutes the four-wheel drive traveling state of the vehicle decreases or disappears, preventing unnecessary energy consumption and improving fuel efficiency. Can be achieved.
[0058]
FIG. 9 shows a modification of the valve mechanism in the driving force transmission device 30. The valve mechanism 30d has two disk-like valve bodies, and the annular groove 36a of the pump disk 36 has Valve bodies 36e1 and 36e2 are arranged on the suction port 36c side and the discharge port 36d side with the communication passage 36b interposed therebetween. The annular groove 36a is provided with stopper portions 36a1 and 36a2 at a portion close to the suction port 36c and a portion close to the discharge port 36d, respectively, and the valve bodies 36e1 and 36e2 are respectively connected to the annular groove 36a by the stopper portions 36a1 and 36a2. The movement within is restricted to a predetermined amount. Each of the stopper portions 36a1 and 36a2 has a cross-sectional shape shown in FIG. 9B, and the viscous fluid flows even when the valve bodies 36e1 and 36e2 are caught by the stopper portions 36a1 and 36a2.
[0059]
In the valve mechanism 30d, for example, the valve body 36e1 closes the communication path 36b when the differential rotation is normal, and the valve body 36e2 closes the communication path 36b when the differential rotation is reversed. Responsiveness at the time of switching from normal rotation to reverse rotation and reverse rotation to normal rotation of the differential rotation is improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a driving force transmission device according to an example of the present invention.
FIG. 2 is a partial perspective view showing a valve mechanism in a housing space portion of a pressing force generating mechanism constituting the driving force transmission device.
FIGS. 3A and 3B are front views showing different operating states of a valve mechanism provided in the pressing force generating mechanism. FIGS.
FIG. 4 is a front view corresponding to FIG. 3A, showing a modification of the valve mechanism.
FIG. 5 is a front view corresponding to FIG. 3A, showing another modification of the valve mechanism.
FIG. 6 is a schematic skeleton diagram of a four-wheel drive vehicle configured by mounting the driving force transmission device.
FIG. 7 is a cross-sectional view showing a driving force transmission device according to another example of the present invention.
FIG. 8 is a cut-away front view of a part of the pump disk corresponding to the arrangement site of the valve mechanism of the driving force transmission device.
9 is a partially omitted front view (a) corresponding to FIG. 8 showing a modification of the valve mechanism, and a cross-sectional view (b) taken along the line bb in FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Driving force transmission apparatus, 10a ... Outer case, 10b ... Inner shaft, 10c ... Friction clutch, 10d ... Pressing force generation mechanism, 10e, 10f, 10g ... Valve mechanism, 11a ... Front housing, 11b ... Rear cover, 12a ... Inner Clutch plate, 12b ... outer clutch plate, 13 ... rotor, 13a ... support shaft part, 13b ... vane part, 13b1 ... thick part, 13b2,13b3 ... thin part, 13c ... communication hole, 14 ... acting piston, 15,16 17 ... Valve body, 16a ... Contact surface, 16b ... Thin part, 21 ... Torrance axle, 22 ... Engine, 23 ... Front differential, 24a, 24a ... Axle shaft, 24b, 24b ... Front wheel, 25, 26 ... Propeller Shaft, 27 ... Rear differential, 28a, 28a ... Axle shaft 28b, 28b ... rear wheel, 30 ... driving force transmission device, 30a ... friction clutch mechanism, 30b ... pump mechanism, 30c, 30d ... valve mechanism, 31 ... outer case, 31a ... inner spline, 32 ... inner shaft, 32a ... shaft Main body, 32b ... inner spline, 33a ... inner clutch plate, 33b ... outer clutch plate, 34a ... pressing plate, 34b ... receiving plate, 35 ... connecting member, 35a ... cylindrical main body, 35b ... inner spline, 35c ... outer spline 36a ... 36a ... circumferential annular groove, 36a1,36a2 ... stopper portion, 36b ... communication passage, 36c, 36d ... hole, 36e, 36e1,36e2 ... valve, 37 ... feed disc, 38 ... cover Body, 38a ... annular recess, 38b ... piston, 38c ... suction hole, 38d ... discharge hole, 38e ... spring member 39 ... working piston, 39a ... annular recess, 39 b ... spring member, R ... housing space, r ... the pressure generating chambers, R1 ... accommodating chamber.

Claims (2)

A vehicle driving force transmission device that constitutes a four-wheel drive vehicle and is disposed between a drive-side rotation shaft and a driven-side rotation shaft of a vehicle, and is connected to each of the rotation shafts and is coaxial with each other. Inner and outer rotating members positioned so as to be relatively rotatable, a friction clutch disposed between the rotating members and transmitting torque between the rotating members by friction engagement, and a pressing force to frictionally engage the friction clutch And a pressing force generation mechanism that reduces or restricts the generation of the pressing force when the vehicle speed is higher than a predetermined speed. A driving force transmission device for a vehicle including means, wherein the pressing force generation mechanism includes a rotor that is positioned in the viscous fluid accommodating space and that rotates relative to the differential rotation of the inner and outer rotating members to generate the pressing force. Rotor type press equipped A generating mechanism, and the pressing force generation control means comprises a valve mechanism provided in front Symbol housing space, the valve mechanism, a pressure generated adjacent provided at the base end portion of the vane portion of the rotor A communication hole that allows the chambers to communicate with each other, and a valve element that closes part or all of the opening of the communication hole to generate the pressing force. The opening of the communicating hole is closed by pressing the opening side of the communicating hole of the vane part by the fluid action of the viscous fluid flowing toward the vane part that is relatively rotated in the space and generated in the pressure generating chamber. And is configured to move to the tip side along one side of the vane portion by the action of centrifugal force generated when the vehicle speed is higher than a predetermined speed, thereby opening the opening portion of the communication hole. A vehicle driving force transmission device. A vehicle driving force transmission device that constitutes a four-wheel drive vehicle and is disposed between a drive-side rotation shaft and a driven-side rotation shaft of a vehicle, and is connected to each of the rotation shafts and is coaxial with each other. Inner and outer rotating members positioned so as to be relatively rotatable, a friction clutch disposed between the rotating members and transmitting torque between the rotating members by friction engagement, and a pressing force to frictionally engage the friction clutch And a pressing force generation mechanism that reduces or restricts the generation of the pressing force when the vehicle speed is higher than a predetermined speed. And a pressing force generating mechanism having a circumferential groove for allowing viscous fluid to flow and rotating relative to each other by the differential rotation of the inner and outer rotating members to generate the pressing force. With pump disc A shear-pump type pressing force generation mechanism, and the pressing force generation control means includes a valve mechanism provided in the circumferential groove, and the valve mechanism is based on a closed portion of both ends of the circumferential groove. A communication passage that is provided at the end and communicates both ends of the circumferential groove with each other, and a valve body that generates the pressing force by closing part or all of the opening of the communication passage. The valve body presses the opening side of the communication hole by the fluid action of the viscous fluid that flows to the communication hole side of the both-end closed portion that is generated in the circular groove when the pump disk is differentially rotated. The opening of the communication hole is opened by closing the opening of the hole and moving to the tip side along one side of the both-end blocking part by the action of centrifugal force generated when the vehicle speed is higher than a predetermined speed. the vehicle driving force transmission apparatus characterized by being configured

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