CA1232824A - Running apparatus for an agricultural vehicle - Google Patents
Running apparatus for an agricultural vehicleInfo
- Publication number
- CA1232824A CA1232824A CA000464906A CA464906A CA1232824A CA 1232824 A CA1232824 A CA 1232824A CA 000464906 A CA000464906 A CA 000464906A CA 464906 A CA464906 A CA 464906A CA 1232824 A CA1232824 A CA 1232824A
- Authority
- CA
- Canada
- Prior art keywords
- piston
- oil
- fluid chamber
- aye
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/4078—Fluid exchange between hydrostatic circuits and external sources or consumers
- F16H61/4096—Fluid exchange between hydrostatic circuits and external sources or consumers with pressure accumulators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/4183—Preventing or reducing vibrations or noise, e.g. avoiding cavitations
Abstract
Abstract of the Disclosure A running apparatus for an agricultural vehicle comprising an oil stepless change speed device, an oil circuit for an oil pump and an oil motor to actuate the oil stepless change speed device and an accumulator.
The accumulator accumulates a surplus of an output pressure of the oil pump when the pressure is higher than a predetermined value and discharges the accumulated pressure when the output pressure of the oil pump is lower than the predetermined value.
The accumulator accumulates a surplus of an output pressure of the oil pump when the pressure is higher than a predetermined value and discharges the accumulated pressure when the output pressure of the oil pump is lower than the predetermined value.
Description
lZ328~24 A RUNNING APPARATUS FOR AN
AGRICULTURAL VEHICLE
Background of the Invention This invention relates to a running apparatus for an agricultural vehicle in which an oil stemless change speed device is provided.
The above-mentioned agricultural vehicle normally has the following drawbacks or troubles. Namely, when pulses occur in the output of an oil pump consisting of the step-less change speed device due to an oil leakage or other causes under such a state that a driving load of the running apparatus is relatively small and driving speeds thereof are relatively fast and that the vehicle runs on a flat road at high speeds, variation of rotation speeds of an oil motor becomes extremely great due to the pulsing output thereof and then brings about great driving noises and gives the vehicle body a compulsive vibration which is discomfort able to a driver.
Summary of the Invention The first object of this invention is to improve a run-nine apparatus for an agricultural vehicle such that speeds of an oil motor are not easily varied even if an oil pump I
~.~,328~'4 produces a pulsing output.
The characteristic construction of this invention for achieving the first object is that a running apparatus for an agricultural vehicle comprises an oil stemless change speed device consisting of an oil pump and an oil motor, oil paths for connecting the oil pump and the oil motor, and an accumulator disposed in parallel with the oil motor between the paths, characterized in that the accumulator is so constructed as to accumulate therein a surplus of an output pressure of the oil pump when the output pressure is greater than a predetermined value and as to discharge an accumulated pressure when the output pressure of the oil pump is smaller than the predetermined value.
Namely, by providing the accumulator in the above-men-toned state, when the output pressure of the pump becomes greater than a predetermined value, the accumulator absorbs and accumulates a surplus pressure of the output pressure and controls the output pressure for the motor to be reduced into a value lower than that of the output pressure of the pump, and when the output pressure is smaller than the predetermined value, the accumulator discharges the accumu-fated pressure so as to control the pressure for the motor to be increased to a value greater than that of the output pressure of the pump.
Therefore, even if pulses occur in the output of the 1~3Z8~
pump, the oil pressure to the motor may be kept substantial-lye at a predetermined value so as to make rotation speeds of the motor constant to the utmost, so that it becomes possible to drive the vehicle comfortably by preventing issues of noises and compulsive vibrations to the vehicle body due to such a pulsing output of the pump.
The second object of this invention is to obtain the above-mentioned advantages by only providing the accumulator with a single piston.
To achieve the second object, the running apparatus for the agricultural vehicle according to this invention cam-proses the accumulator which comprises a piston disposed reciprocally slid ably, a pair of oil pressure chambers for the piston, each being connected to a pair of the oil paths and arranged separately at each end of the piston, and an accumulating spring or springs arranged to urge the piston to return to a neutral position.
Namely, since a pair of the oil pressure chambers for the piston are connected respectively to a pair of the oil paths and arranged separately at each end of the piston and then the accumulating spring or springs are arranged to urge the piston to return to a neutral position, the spring or springs are deformed flexibly by the oil pressure acting on an end of the piston when forward running and the spring or springs are deformed flexibly by the oil pressure acting on . I, ,;.
~2328~L
the other end of the piston when rearward running, and therefore accumulation and discharge of the oil pressure may be carried out in both the forward and rearward running by providing only such a single piston.
Therefore, it is not necessary to provide a changing means or to save trouble of provision thereof in comparison with such a case that it is necessary to connect an accumu-later having a piston only on the side of the supplying path to the motor with respect to a pair of the paths.
Thus, it may be driven comfortably in any of forward and rearward running. This running apparatus has been obtain-Ed simple in construction and operation.
Other advantages of this invention will be apparent from the following description.
grief Description of the Drawings The drawings show an embodiment of a running apparatus for an agricultural vehicle in which:-Fig. 1 is a side elevation of an agricultural tractor, Fig. 2 is a side view of a mount section of an oil stemless change speed device, Fig. 3 is an oil circuit, Fig. 4 and Fig. 5 are sectional views of an accumulator, Fig. 6 is a sectional view of another embodiment of an accumulator, 12~};28~:~
Fig. 7 is a sectional view of a further embodiment of an accumulator, and Fig. 8 is a circuit for another embodiment of a change speed device.
Detailed Description of the Preferred Embodiments As shown in Fig. 1, an agricultural tractor is construct-Ed such that a lift arm 1 which is singable up and down and liftable connected to any type of working implements such as a rotary cultivating device (not shown), and a power take-off shaft 2 for transmitting a power to the connected working implement, are disposed at a rear portion of a self-propelled vehicle body having a running device of wheel type.
In a drive line from an engine 3 to front wheels 4 and rear wheels 5, there is provided an oil stemless change speed device 6 which is changeable from neutral to forward and to rearward. As shown in Fig. 2, a change speed operating pedal 14 which is operatively connected to an operating arm 7 singable about an axis Pi of the change speed device 6, via a singable connecting member Andy a rotary shaft 13, is singable attached to a transmission case 16 which come proses a tractor body frame. A roller 9 is singable attached to the change speed device 6 via a swing support arm 8 to be singable about an axis Pi. The roller 9 is urged to contact with a V-shaped cam surface pa of the lower 123~8~24 end of the operating arm 7 by means of a spring 10 so that the operating arm 7 and the change speed pedal 14 may be urged to return to a neutral position _. By stepping the pedal 14 on the side of forward or rearward of the tractor, the operating arm 7 is swung to forward F or the rearward R and as the pedal 14 is stepped more deeply, the operating arm 7 is close to the side of high speed. Namely, it is so constructed that the change speed device 6 is operated by the pedal 14 so as to carry out operations of changing forward and rearward running, speeds and stopping of the tractor.
As shown in Fig. 2, an accumulator 15 is attached to the lower portion of the change speed device 6. As shown in Fig. 3, the accumulator 15 is connected to a pair of oil paths aye, 20b for an oil pump 18 as an element of the change speed device 6 and an oil motor 19 via a pair of suction and discharge oil paths aye, 17b formed with the accumulator 15, so as to control variations of rotation speeds of the motor 19 due to pulsing outputs of the pump 18 even if pulsing occurs in the outputs of the pump 18.
Namely, the accumulator 15 is constructed such that when the output pressure of the pump 18 is greater than a pro-determined value a surplus pressure over the predetermined value of the output pressure is absorbed and accumulated in the accumulator and controls the oil pressure acting on the ~232~
motor to be reduced to a value lower than the output pressure of the pump. Further, the accumulator 15 is also constructed such that when the output pressure of the pump is smaller than a predetermined value the accumulator discharges an accumulated pressure and controls the oil pressure acting on the motor to be increased to a value higher than the output of the pump. A
charge pump 18' supplies oil to the connecting paths aye 20b in such a state that the pressure of the pump 18 is 10 Compensated.
The accumulator 15 is constructed as shown in Fig. 4 or Fig. 5.
Namely, as shown in Fig. 4, a single piston 21 is housed in an accumulator case 16 to slide reciprocatingly, and first and second oil chambers aye, 22b for the piston 21 are provided therein. The first oil chamber aye is connected to the connecting path aye via the oil path aye in the accumulator case 16 and the other second oil chamber 22b is connected to the other connecting path 20b via the path 17b in the accumulator case 16, these thus being arranged separately adjacent each end of the piston 21 in such a state that these urge the piston 21 to return to a neutral position in cooperation with each other. Namely, when forward running, an oil flows into the first oil chamber aye and the piston 21 is pushed to slide towards 12328;~4 the second oil chamber 22b so that the spring 23b may be compressed. When rearward running, an oil flows into the second oil chamber 22b and pushes the piston towards the first oil chamber aye so that the other spring aye may be compressed.
As shown in Fig. 5, a single piston 24 is housed in an accumulator case; 16 to slide reciprocatingly, and first and second oil chambers aye, 25b for the piston 24 are provided therein. The oil chamber aye is connected to the connecting path aye via the path aye in the accumulator case 16 and the other chamber 25b is connected to the other connecting path 20b via the oil path 17b in the accumulator case 16, these chambers being separately arranged adjacent each end of the piston 24.
A single compression spring 26 is housed in the first oil chamber aye. An end portion of the spring 26 is supported by a side surface aye of an intermediate portion of the piston 24 and an oil chamber interior wall aye of the accumulator case 16 via a first spring receiver 27 which is slid ably fitted to the piston 24. The other end portion of the spring 26 is supported by an end surface 24b of the piston 24 and an oil chamber interior wall 16b of the case 16 via a second spring receiver 28 which is slid ably fitted to the piston 24 so that the spring 26 may urge the piston 24 to return to a neutral position where the side surface 12321~24 aye of the intermediate portion and the oil chamber interior wall aye maze substantially a flat plane.
Namely, in the case of forward running, a pressure oil flows into the first oil chamber aye and the piston 24 is slimed towards the second oil chamber 25b, and compresses the spring 26 via the end surface 24b and the second spring receiver 28 so as to accumulate a power therewith. Further, when rearward running, an oil flows into the second oil chamber 25b and the piston 24 is slimed towards the first oil chamber aye and then compresses the spring 26 via the intermediate surface aye and the first spring receiver 27 so as to accumulate a power therewith.
Another aspect of the accumulator 15 is as shown in Fig. 6. Two pistons aye and 121b are housed slid ably in an accumulator case 122. An oil chamber aye for forward running is formed with the accumulator case 122 adjacent one end of the piston aye in such a state that the oil chamber is in communication with an inlet or outlet port ' aye. An oil chamber 123b for rearward running is formed with the accumulator case 122 adjacent one end of the other piston 121b in such a state that the oil chamber is in I! communication with an inlet or outlet port 124b. A compress soon spring 125 is interposed between the two pistons aye and 121b. Each of the two pistons aye and 121b has a spring housing space 126 and a connection path 127 to the .
~328~4 oil chamber aye or 123b, and a valve 128 for the connect lion path 127 is housed slid ably in each of the pistons aye and 121b. The valve 128 of the piston aye or 121b in an accumulating position is maintained in a closed position in contact with a valve seat 129 by means of an oil pressure in the oil chamber aye or 123b. On the contrary, to enable a spring compression action for the piston aye or 121b, the valve 128 of the piston 121b or aye in a discharging position is operated into an open state remote from a valve seat 129 by means of a pressing action of the piston 121b or aye caused by the oil stayed in the spring housing space 126 into which an oil leaks and flows from the oil chamber aye or 123b through between the piston aye or 121b and the accumulator case 122.
The leaked oil in the spring housing space 126 flows into the oil chamber 123b or aye through the connection path 127 in order to return same to either of the connecting oil paths aye or 20b (in Fig. 3) which has a lower oil pressure than the other. In other words, the leaked oil from the oil chamber aye or 123b is returned to the change speed device 6 by means of the path aye and 17b for connecting the j accumulator 15 and the change speed device 6, and by utilize in an accumulating function of the accumulator 15.
A further aspect of the accumulator 15 is shown in Fig. 7. A single piston 30 is slid ably housed in an , ~2328~
accumulator case 31, and two of four compression springs aye, aye, 32b and 32b are separately arranged on each side of the piston 30 so as to urge the piston 30 to return to a neutral position. An oil chamber aye for forward run-nine is formed with the accumulator case 31 adjacent one end of the piston 30 to be in communication with an inlet or an outlet port aye. An oil chamber 33b for rearward running is formed adjacent the other end of the piston 30 to be in communication with an inlet or an outlet port 34b.
Fig. 8 shows another aspect of the stemless change speed device 6. A relief valve 218 and a neutral valve 219 are housed in a change speed device casing 220 to be a unit. The relief valve 218 prevents breakage of the oil path aye or 20b by escaping an oil pressure from the path aye or 20b to the path aye or 20b which is a return path from the oil motor 19 to the oil pump 18, when pressures in the oil pump 18, the oil motor 19, the connecting oil paths aye and 20b for the oil pump 18 and the oil motor 19, becomes higher than a predetermined value. The neutral valve 219 functions to stop the oil motor 19 by escaping the oil from the oil pump 18 out of the connecting oil paths aye and 20b when an output pressure of the oil pump 18 becomes lower than a predetermined value. A charge oil path 222 is connected to a relief oil path 22 in which the relief valve 218 is provided, so that an oil from a charge 1232~3~4 pump 18~ may be charged to the connecting oil paths aye and 20b via the relief oil path 22. A drain port aye for the oil pump 18, a drain port lea for the oil motor 19, a discharge oil port aye of the relief valve 224 to the charge oil path 222, and a discharge oil port aye of the neutral valve 219 are opened respectively in the change speed device casing 220~ so that a leaked oil from the oil pump 18 and the oil motor 19, a surplus oil from the charge pump 18' and an escaping oil from the connecting oil paths aye and 20b due to the neutral valve 219, may be discharged respectively into the change speed device casing 220.
Further, it is constructed such that the discharged oil gathered in the casing 220 returns to a tank 227 via a relief valve 225 for controlling an oil leakage of the oil pump 18 or the oil motor 19, and a drain oil path 226.
AGRICULTURAL VEHICLE
Background of the Invention This invention relates to a running apparatus for an agricultural vehicle in which an oil stemless change speed device is provided.
The above-mentioned agricultural vehicle normally has the following drawbacks or troubles. Namely, when pulses occur in the output of an oil pump consisting of the step-less change speed device due to an oil leakage or other causes under such a state that a driving load of the running apparatus is relatively small and driving speeds thereof are relatively fast and that the vehicle runs on a flat road at high speeds, variation of rotation speeds of an oil motor becomes extremely great due to the pulsing output thereof and then brings about great driving noises and gives the vehicle body a compulsive vibration which is discomfort able to a driver.
Summary of the Invention The first object of this invention is to improve a run-nine apparatus for an agricultural vehicle such that speeds of an oil motor are not easily varied even if an oil pump I
~.~,328~'4 produces a pulsing output.
The characteristic construction of this invention for achieving the first object is that a running apparatus for an agricultural vehicle comprises an oil stemless change speed device consisting of an oil pump and an oil motor, oil paths for connecting the oil pump and the oil motor, and an accumulator disposed in parallel with the oil motor between the paths, characterized in that the accumulator is so constructed as to accumulate therein a surplus of an output pressure of the oil pump when the output pressure is greater than a predetermined value and as to discharge an accumulated pressure when the output pressure of the oil pump is smaller than the predetermined value.
Namely, by providing the accumulator in the above-men-toned state, when the output pressure of the pump becomes greater than a predetermined value, the accumulator absorbs and accumulates a surplus pressure of the output pressure and controls the output pressure for the motor to be reduced into a value lower than that of the output pressure of the pump, and when the output pressure is smaller than the predetermined value, the accumulator discharges the accumu-fated pressure so as to control the pressure for the motor to be increased to a value greater than that of the output pressure of the pump.
Therefore, even if pulses occur in the output of the 1~3Z8~
pump, the oil pressure to the motor may be kept substantial-lye at a predetermined value so as to make rotation speeds of the motor constant to the utmost, so that it becomes possible to drive the vehicle comfortably by preventing issues of noises and compulsive vibrations to the vehicle body due to such a pulsing output of the pump.
The second object of this invention is to obtain the above-mentioned advantages by only providing the accumulator with a single piston.
To achieve the second object, the running apparatus for the agricultural vehicle according to this invention cam-proses the accumulator which comprises a piston disposed reciprocally slid ably, a pair of oil pressure chambers for the piston, each being connected to a pair of the oil paths and arranged separately at each end of the piston, and an accumulating spring or springs arranged to urge the piston to return to a neutral position.
Namely, since a pair of the oil pressure chambers for the piston are connected respectively to a pair of the oil paths and arranged separately at each end of the piston and then the accumulating spring or springs are arranged to urge the piston to return to a neutral position, the spring or springs are deformed flexibly by the oil pressure acting on an end of the piston when forward running and the spring or springs are deformed flexibly by the oil pressure acting on . I, ,;.
~2328~L
the other end of the piston when rearward running, and therefore accumulation and discharge of the oil pressure may be carried out in both the forward and rearward running by providing only such a single piston.
Therefore, it is not necessary to provide a changing means or to save trouble of provision thereof in comparison with such a case that it is necessary to connect an accumu-later having a piston only on the side of the supplying path to the motor with respect to a pair of the paths.
Thus, it may be driven comfortably in any of forward and rearward running. This running apparatus has been obtain-Ed simple in construction and operation.
Other advantages of this invention will be apparent from the following description.
grief Description of the Drawings The drawings show an embodiment of a running apparatus for an agricultural vehicle in which:-Fig. 1 is a side elevation of an agricultural tractor, Fig. 2 is a side view of a mount section of an oil stemless change speed device, Fig. 3 is an oil circuit, Fig. 4 and Fig. 5 are sectional views of an accumulator, Fig. 6 is a sectional view of another embodiment of an accumulator, 12~};28~:~
Fig. 7 is a sectional view of a further embodiment of an accumulator, and Fig. 8 is a circuit for another embodiment of a change speed device.
Detailed Description of the Preferred Embodiments As shown in Fig. 1, an agricultural tractor is construct-Ed such that a lift arm 1 which is singable up and down and liftable connected to any type of working implements such as a rotary cultivating device (not shown), and a power take-off shaft 2 for transmitting a power to the connected working implement, are disposed at a rear portion of a self-propelled vehicle body having a running device of wheel type.
In a drive line from an engine 3 to front wheels 4 and rear wheels 5, there is provided an oil stemless change speed device 6 which is changeable from neutral to forward and to rearward. As shown in Fig. 2, a change speed operating pedal 14 which is operatively connected to an operating arm 7 singable about an axis Pi of the change speed device 6, via a singable connecting member Andy a rotary shaft 13, is singable attached to a transmission case 16 which come proses a tractor body frame. A roller 9 is singable attached to the change speed device 6 via a swing support arm 8 to be singable about an axis Pi. The roller 9 is urged to contact with a V-shaped cam surface pa of the lower 123~8~24 end of the operating arm 7 by means of a spring 10 so that the operating arm 7 and the change speed pedal 14 may be urged to return to a neutral position _. By stepping the pedal 14 on the side of forward or rearward of the tractor, the operating arm 7 is swung to forward F or the rearward R and as the pedal 14 is stepped more deeply, the operating arm 7 is close to the side of high speed. Namely, it is so constructed that the change speed device 6 is operated by the pedal 14 so as to carry out operations of changing forward and rearward running, speeds and stopping of the tractor.
As shown in Fig. 2, an accumulator 15 is attached to the lower portion of the change speed device 6. As shown in Fig. 3, the accumulator 15 is connected to a pair of oil paths aye, 20b for an oil pump 18 as an element of the change speed device 6 and an oil motor 19 via a pair of suction and discharge oil paths aye, 17b formed with the accumulator 15, so as to control variations of rotation speeds of the motor 19 due to pulsing outputs of the pump 18 even if pulsing occurs in the outputs of the pump 18.
Namely, the accumulator 15 is constructed such that when the output pressure of the pump 18 is greater than a pro-determined value a surplus pressure over the predetermined value of the output pressure is absorbed and accumulated in the accumulator and controls the oil pressure acting on the ~232~
motor to be reduced to a value lower than the output pressure of the pump. Further, the accumulator 15 is also constructed such that when the output pressure of the pump is smaller than a predetermined value the accumulator discharges an accumulated pressure and controls the oil pressure acting on the motor to be increased to a value higher than the output of the pump. A
charge pump 18' supplies oil to the connecting paths aye 20b in such a state that the pressure of the pump 18 is 10 Compensated.
The accumulator 15 is constructed as shown in Fig. 4 or Fig. 5.
Namely, as shown in Fig. 4, a single piston 21 is housed in an accumulator case 16 to slide reciprocatingly, and first and second oil chambers aye, 22b for the piston 21 are provided therein. The first oil chamber aye is connected to the connecting path aye via the oil path aye in the accumulator case 16 and the other second oil chamber 22b is connected to the other connecting path 20b via the path 17b in the accumulator case 16, these thus being arranged separately adjacent each end of the piston 21 in such a state that these urge the piston 21 to return to a neutral position in cooperation with each other. Namely, when forward running, an oil flows into the first oil chamber aye and the piston 21 is pushed to slide towards 12328;~4 the second oil chamber 22b so that the spring 23b may be compressed. When rearward running, an oil flows into the second oil chamber 22b and pushes the piston towards the first oil chamber aye so that the other spring aye may be compressed.
As shown in Fig. 5, a single piston 24 is housed in an accumulator case; 16 to slide reciprocatingly, and first and second oil chambers aye, 25b for the piston 24 are provided therein. The oil chamber aye is connected to the connecting path aye via the path aye in the accumulator case 16 and the other chamber 25b is connected to the other connecting path 20b via the oil path 17b in the accumulator case 16, these chambers being separately arranged adjacent each end of the piston 24.
A single compression spring 26 is housed in the first oil chamber aye. An end portion of the spring 26 is supported by a side surface aye of an intermediate portion of the piston 24 and an oil chamber interior wall aye of the accumulator case 16 via a first spring receiver 27 which is slid ably fitted to the piston 24. The other end portion of the spring 26 is supported by an end surface 24b of the piston 24 and an oil chamber interior wall 16b of the case 16 via a second spring receiver 28 which is slid ably fitted to the piston 24 so that the spring 26 may urge the piston 24 to return to a neutral position where the side surface 12321~24 aye of the intermediate portion and the oil chamber interior wall aye maze substantially a flat plane.
Namely, in the case of forward running, a pressure oil flows into the first oil chamber aye and the piston 24 is slimed towards the second oil chamber 25b, and compresses the spring 26 via the end surface 24b and the second spring receiver 28 so as to accumulate a power therewith. Further, when rearward running, an oil flows into the second oil chamber 25b and the piston 24 is slimed towards the first oil chamber aye and then compresses the spring 26 via the intermediate surface aye and the first spring receiver 27 so as to accumulate a power therewith.
Another aspect of the accumulator 15 is as shown in Fig. 6. Two pistons aye and 121b are housed slid ably in an accumulator case 122. An oil chamber aye for forward running is formed with the accumulator case 122 adjacent one end of the piston aye in such a state that the oil chamber is in communication with an inlet or outlet port ' aye. An oil chamber 123b for rearward running is formed with the accumulator case 122 adjacent one end of the other piston 121b in such a state that the oil chamber is in I! communication with an inlet or outlet port 124b. A compress soon spring 125 is interposed between the two pistons aye and 121b. Each of the two pistons aye and 121b has a spring housing space 126 and a connection path 127 to the .
~328~4 oil chamber aye or 123b, and a valve 128 for the connect lion path 127 is housed slid ably in each of the pistons aye and 121b. The valve 128 of the piston aye or 121b in an accumulating position is maintained in a closed position in contact with a valve seat 129 by means of an oil pressure in the oil chamber aye or 123b. On the contrary, to enable a spring compression action for the piston aye or 121b, the valve 128 of the piston 121b or aye in a discharging position is operated into an open state remote from a valve seat 129 by means of a pressing action of the piston 121b or aye caused by the oil stayed in the spring housing space 126 into which an oil leaks and flows from the oil chamber aye or 123b through between the piston aye or 121b and the accumulator case 122.
The leaked oil in the spring housing space 126 flows into the oil chamber 123b or aye through the connection path 127 in order to return same to either of the connecting oil paths aye or 20b (in Fig. 3) which has a lower oil pressure than the other. In other words, the leaked oil from the oil chamber aye or 123b is returned to the change speed device 6 by means of the path aye and 17b for connecting the j accumulator 15 and the change speed device 6, and by utilize in an accumulating function of the accumulator 15.
A further aspect of the accumulator 15 is shown in Fig. 7. A single piston 30 is slid ably housed in an , ~2328~
accumulator case 31, and two of four compression springs aye, aye, 32b and 32b are separately arranged on each side of the piston 30 so as to urge the piston 30 to return to a neutral position. An oil chamber aye for forward run-nine is formed with the accumulator case 31 adjacent one end of the piston 30 to be in communication with an inlet or an outlet port aye. An oil chamber 33b for rearward running is formed adjacent the other end of the piston 30 to be in communication with an inlet or an outlet port 34b.
Fig. 8 shows another aspect of the stemless change speed device 6. A relief valve 218 and a neutral valve 219 are housed in a change speed device casing 220 to be a unit. The relief valve 218 prevents breakage of the oil path aye or 20b by escaping an oil pressure from the path aye or 20b to the path aye or 20b which is a return path from the oil motor 19 to the oil pump 18, when pressures in the oil pump 18, the oil motor 19, the connecting oil paths aye and 20b for the oil pump 18 and the oil motor 19, becomes higher than a predetermined value. The neutral valve 219 functions to stop the oil motor 19 by escaping the oil from the oil pump 18 out of the connecting oil paths aye and 20b when an output pressure of the oil pump 18 becomes lower than a predetermined value. A charge oil path 222 is connected to a relief oil path 22 in which the relief valve 218 is provided, so that an oil from a charge 1232~3~4 pump 18~ may be charged to the connecting oil paths aye and 20b via the relief oil path 22. A drain port aye for the oil pump 18, a drain port lea for the oil motor 19, a discharge oil port aye of the relief valve 224 to the charge oil path 222, and a discharge oil port aye of the neutral valve 219 are opened respectively in the change speed device casing 220~ so that a leaked oil from the oil pump 18 and the oil motor 19, a surplus oil from the charge pump 18' and an escaping oil from the connecting oil paths aye and 20b due to the neutral valve 219, may be discharged respectively into the change speed device casing 220.
Further, it is constructed such that the discharged oil gathered in the casing 220 returns to a tank 227 via a relief valve 225 for controlling an oil leakage of the oil pump 18 or the oil motor 19, and a drain oil path 226.
Claims (5)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:
1. A running apparatus for an agricultural vehicle comprising:
a hydraulic stepless change speed device including a hydraulic pump, a hydraulic motor, and a looped line con-nected to the pump and motor so that when the pump is operated, fluid passes through the line to actuate the motor;
means hydraulically connected to the looped line for feeding and discharging said fluid to the looped line to main-tain pressure in the line substantially contantly, and accumulator means hydraulically connected to the looped line parallel to said hydraulic motor, said accumulator means comprising a casing, first and second fluid chambers defined in said casing and respectively connected to said looped line, a piston chamber defined in said casing to communicate with said first and second fluid chambers, a piston slidably situated in said piston chamber, and a single spring means arranged in the casing to urge said piston to a neutral position, wherein said accumulator means absorbs pressure pulsations produced in said looped line by elasticity of said single spring means so that the motor is operable free from the pulsations.
a hydraulic stepless change speed device including a hydraulic pump, a hydraulic motor, and a looped line con-nected to the pump and motor so that when the pump is operated, fluid passes through the line to actuate the motor;
means hydraulically connected to the looped line for feeding and discharging said fluid to the looped line to main-tain pressure in the line substantially contantly, and accumulator means hydraulically connected to the looped line parallel to said hydraulic motor, said accumulator means comprising a casing, first and second fluid chambers defined in said casing and respectively connected to said looped line, a piston chamber defined in said casing to communicate with said first and second fluid chambers, a piston slidably situated in said piston chamber, and a single spring means arranged in the casing to urge said piston to a neutral position, wherein said accumulator means absorbs pressure pulsations produced in said looped line by elasticity of said single spring means so that the motor is operable free from the pulsations.
2. The apparatus of claim 1, wherein the piston comprises a middle portion projecting into the first fluid chamber and an end portion projecting into the first fluid chamber, and wherein said accumulator means further includes a first spring receiver slidably mounted on the middle portion of the piston projecting into the first fluid chamber and a second spring receiver having a tubular portion con-taining the end portion of the piston protecting into the first fluid chamber, said single spring means being arranged between the first and second spring receivers.
3. The apparatus of claim 2, wherein the first fluid chamber comprises a first inner end wall and a second inner end wall, the middle portion of the piston comprises a first radial surface and the end portion of the piston com-prises a second radial surface, and wherein said first spring receiver engages the first radial surface of the middle portion of the piston and the first inner end wall of the first fluid chamber, and said second spring receiver engages the second radial surface of the end portion of the piston and the second inner end wall of the first fluid chamber.
4. The apparatus of claim 1, wherein the piston comprises a first tubular piston portion and a second tubular piston portion defining a space therebetween and therein, said single spring means being fitted in the space between and inside of said first and second tubular piston portions, and wherein said first tubular piston portion and said piston chamber define said first fluid chamber therebetween and said second tubular piston portion and said piston chamber define said second fluid chamber therebetween.
5. The apparatus of claim 4, wherein said first tubular piston portion includes a first connection path intercommunicating the space between and in said tubular piston portions and said first fluid chamber and a first valve means for opening and closing said first connection path, and said second tubular piston portion includes a second connection path intercommunicating the space between and in said tubular piston portions and said second fluid chamber and a second valve means for opening and closing said second connection path.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18621283U JPS6092620U (en) | 1983-11-30 | 1983-11-30 | Traveling device for mobile agricultural machinery |
| JP186212/1983 | 1983-11-30 | ||
| JP186177/1983 | 1983-12-01 | ||
| JP1983186177U JPS6093517U (en) | 1983-12-01 | 1983-12-01 | Traveling device for mobile agricultural machinery |
| JP190565/1983 | 1983-12-09 | ||
| JP19056583U JPS6096125U (en) | 1983-12-09 | 1983-12-09 | Traveling device for mobile agricultural machinery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232824A true CA1232824A (en) | 1988-02-16 |
Family
ID=27325697
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000464906A Expired CA1232824A (en) | 1983-11-30 | 1984-10-05 | Running apparatus for an agricultural vehicle |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU558465B2 (en) |
| CA (1) | CA1232824A (en) |
| DE (1) | DE3441484A1 (en) |
| FR (1) | FR2555696B1 (en) |
| GB (1) | GB2152639B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3806464A1 (en) * | 1988-03-01 | 1989-09-14 | Agrar Spezial Maschinen | Damping arrangement for damping pressure shocks in a fluid flow |
| DE3916854A1 (en) * | 1988-11-30 | 1989-09-28 | Siegfried Klett | FLUIDIC PRINT STORAGE |
| DE3843570C2 (en) * | 1988-12-23 | 1997-12-18 | Teves Gmbh Alfred | Damping device for hydraulic brake systems |
| FR2770262B1 (en) * | 1997-10-23 | 2004-10-29 | Christian Pitavy | DIGITAL DEVICE FOR TRANSFERRING ENERGY BY ELASTICITY |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1425783B2 (en) * | 1963-09-06 | 1971-12-16 | Linde Ag, 6200 Wiesbaden | HYDROSTATIC GEAR WITH CLOSED CIRCUIT |
| GB1108243A (en) * | 1964-04-22 | 1968-04-03 | Calmec Extruform Ltd | Improvements in apparatus for moulding articles from sheet plastics material |
| FR2386709A1 (en) * | 1977-04-07 | 1978-11-03 | Gratzmuller Claude | Gravity controlled hydraulic accumulator - has dead weight piston within cylinder contg. lubricating oil with inlet and outlet at opposite ends |
| US4450870A (en) * | 1982-03-15 | 1984-05-29 | The Bendix Corporation | Liquid spring accumulator with self-charging means |
-
1984
- 1984-10-05 CA CA000464906A patent/CA1232824A/en not_active Expired
- 1984-10-09 AU AU34049/84A patent/AU558465B2/en not_active Ceased
- 1984-10-09 GB GB08425521A patent/GB2152639B/en not_active Expired
- 1984-10-30 FR FR8416606A patent/FR2555696B1/en not_active Expired - Fee Related
- 1984-11-13 DE DE19843441484 patent/DE3441484A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| GB2152639B (en) | 1987-05-07 |
| AU3404984A (en) | 1985-06-06 |
| DE3441484A1 (en) | 1986-03-13 |
| FR2555696B1 (en) | 1991-03-29 |
| GB8425521D0 (en) | 1984-11-14 |
| DE3441484C2 (en) | 1989-02-16 |
| FR2555696A1 (en) | 1985-05-31 |
| GB2152639A (en) | 1985-08-07 |
| AU558465B2 (en) | 1987-01-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |