Abstract:
There is provided a tractor with an improved clutch housing structure, which includes a hydro-static transmission (HST) positioned between a clutch and a secondary transmission, to transmit power. The tractor comprises: a clutch housing with the clutch and the HST positioned inside; a partition to separate the clutch from the HST formed inside the clutch housing; and a heat-radiating opening formed in the partition.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2016-0046154, filed on Apr. 15, 2016, the disclosure of which is hereby incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to a tractor and more particularly, to a tractor with an improved clutch housing in which the clutch housing provided to the tractor includes a hydro-static transmission (HST). 
       2. Description of the Related Art 
       [0003]    In general, although a tractor as a vehicle for agricultural working is structurally similar to a general vehicle, since it has a stronger engine than that of a general vehicle, it has a high traction power and is strong to be usually used for farming. To be used for farming, various farm working machineries are selectively attached to the front, back or front and back of the body of the vehicle. 
         [0004]    On the work features, a tractor mainly used for farming is frequently required to change speed from low speed to high speed or from high speed to low speed and to shift gears in a forward or reverse movement direction. 
         [0005]    Therefore, a hydro-static transmission (HST) is widely adopted as the means to secure the easiness in operating the power transmission during work or driving, further in operating a tractor. 
         [0006]    The HST includes a variable capacity hydraulic oil pump directly which is connected to an output shaft of an engine, and a fixed displacement hydraulic motor which rotates by hydraulic fluid provided from the hydraulic oil pump and outputs substantial running power. The rotation speed and rotation direction of the fixed displacement hydraulic motor are changed by being operatively connected to the operation of changing the angle of a swash plate of the variable capacity hydraulic oil pump. 
         [0007]    A power transmission process of a tractor will be described in reference to the power transmission system diagram in  FIG. 1 . 
         [0008]    In the power transmission process of a tractor as shown in  FIG. 1 , the power which is output from an engine  10  is transmitted to a hydro-static transmission (hereinafter, referred to as “HST”)  31  of a primary transmission. 
         [0009]    The hydraulic power after the transmission by the EIST  31  is transmitted to right and left front wheels  70  as front-wheel driving power or to right and left rear wheels  80  as rear-wheel driving power, through a secondary transmission  41  for driving which is structured by using a gear-type transmission. 
         [0010]    Of the power which is output from the engine  10 , mechanical power is transmitted and available when needed at a PTO (power take-off) shaft  50  as working power, through a PTO clutch  51  and a PTO transmission  52 , and the hydraulic power continuously transmitted through a HST  31  is transmitted at a proper speed for driving or working in the secondary transmission  41 , to be transmitted to the rear wheels or the rear and front wheels through a power transmission shaft. 
         [0011]    Multi-plate type side brakes  60  to brake the rear wheels  80  are positioned at a rear transmission shaft which transmits the power of the HST  31  to the right and left rear wheels  80 . 
         [0012]    In the power transmission system diagram of the tractor, a clutch to control the power transmission of the engine  10  is positioned between the engine  10  and the HST  31 . 
         [0013]    Korean Published Patent Publication. No. 10-2013-0103456 (entitled: “Transmission apparatus for tractor”, hereinafter, referred to as “Prior Art 1”) discloses a structure of a transmission apparatus for a tractor as shown in  FIG. 2 . 
         [0014]    In  FIG. 2 , a clutch housing  20  to include a clutch inside is positioned at the back of an engine, a HST housing  30  to include a HST  31  as a primary transmission inside is positioned at the back of the clutch housing  20 , and a mission housing  40  to include a secondary transmission  41  for driving is positioned at the back of the HST housing  30 . 
         [0015]    Accordingly, the power of the engine is input to an input shaft (pump shaft) of the HST  31  through the clutch inside the clutch housing  20 , the transmission power which is taken off from an output shaft (motor shaft) of the HST  31 , is transmitted to three gears in the secondary transmission  41  for driving in the mission housing  40 . The finally transmitted power is transmitted to the right and left rear wheels  80  through a rear differential, some of the finally transmitted power is taken off to be transmitted to the right and left front wheels  70  which are steered through a front differential, constituting a four-wheel drive transmission system. 
         [0016]    However, in the conventional transmission apparatus disclosed in Prior Art 1, since the HST  31  positioned between the clutch housing  20  and the mission housing  40  is included in the separate HST housing  30  and a HST filter (not shown) is mounted through a filter bracket separately positioned outside the HST housing  30 , the number of components increases and therefore the structure becomes very complicated, the cost of production rises and the productivity is lowered. 
         [0017]    Further, it is very difficult to connect the input shaft of the HST  31  included in the HST housing  30  to the clutch inside the clutch housing  20 . 
         [0018]    Furthermore, since the inside of the clutch housing  20  including the clutch is closed, a lot of heat is generated by the operation of the clutch and moisture is generated inside the clutch housing  20  due to a difference from the outside temperature. 
         [0019]    Since the technology of the tractor and the transmission apparatus of the tractor is fully described in the prior art, no further detailed description thereof will be presented. 
       PRIOR ART DOCUMENT 
     Patent Document 
       [0000]    
       
         Prior Art 1: Korean Published Patent Publication No. 10-2013-0103456 
         Prior Art 2: Korean Registered Patent Publication No. 10-0602527 
       
     
       SUMMARY OF THE INVENTION 
       [0022]    Therefore, it is an object of the present invention to solve the above problems and to provide a tractor with an improved clutch housing structure in which a hydro-static transmission (HST) provided between a clutch housing and a mission housing is included in the clutch housing, enabling a simple and compact structure of a power transmission apparatus. 
         [0023]    It is another object of the present invention to provide a tractor with an improved clutch housing structure in which a clutch included inside a clutch housing is isolated from the HST and a heat-radiating opening is positioned in the clutch housing, emitting the heat generated in the clutch housing to the outside. 
         [0024]    In accordance with an embodiment of the present invention, there is provided a tractor with an improved clutch housing structure, which includes a hydro-static transmission (HST) positioned between a clutch and a secondary transmission, to transmit power. The tractor comprises: a clutch housing with the clutch and the HST positioned inside; a partition to separate the clutch from the HST formed inside the clutch housing; and a heat-radiating opening formed in the partition. 
         [0025]    The tractor with an improved clutch housing structure further comprises: a filter positioned at the heat-radiating opening of the partition, to prevent the clutch from being contaminated. 
         [0026]    The tractor with an improved clutch housing structure further comprises: a guide shaft pipe formed in the partition, to guide a clutch release hub provided to the clutch. 
         [0027]    The tractor with an improved clutch housing structure further comprises: a mounting block with an oil passage through which oil enters/exits inside, which is integrally formed with the clutch housing and mounted with a HST filter. 
         [0028]    The tractor with an improved clutch housing structure further comprises: an assembly hole formed in the clutch housing; and a finish cap to be connected attachably/detachably to the assembly hole. 
       Advantageous Effects of the Invention 
       [0029]    According to the tractor with the improved clutch housing structure of the present invention, the length of the clutch housing is extended to include the clutch in the front section of the clutch housing and to include the HST in the rear section of the clutch housing, thereby enabling a simple and compact structure of a transmission apparatus of the tractor and therefore reducing the cost of production. 
         [0030]    Further, the mounting block with the oil passage through which the oil enters and exits is integrally formed at the outer side of the clutch housing and the HST filter is directly mounted on the mounting block, thereby making the compact structure of the dutch housing. 
         [0031]    Further, the partition to separate the clutch and the HST is installed in the clutch housing and the heat-radiating opening is formed at the partition, thereby minimizing the contamination of the clutch and discharging the heat generated in the clutch housing to the outside. 
         [0032]    Further, the filter is provided to the heat-radiating opening of the partition, thereby preventing pollutants from penetrating to the front section of the clutch housing where the clutch is included, to safely protect the clutch. 
     
    
     
       BRIEF DESCRIPTION OF ME DRAWINGS 
         [0033]    The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail the preferred embodiments thereof with reference to the attached drawings in which: 
           [0034]      FIG. 1  is a power transmission system diagram of a tractor which a driving system of a general hydro-static transmission (HST) is applied to; 
           [0035]      FIG. 2  is a sectional view of a power transmission apparatus provided to the conventional tractor; 
           [0036]      FIG. 3  is a perspective view of a combined power transmission system far a tractor according to the present invention; 
           [0037]      FIG. 4  is a front view of the constitution of the power transmission system according to the present invention; 
           [0038]      FIG. 5  is a sectional view of the combined power transmission system according to the present invention; 
           [0039]      FIG. 6  is a right side view of the constitution of the power transmission system of  FIG. 3 ; and 
           [0040]      FIG. 7  is a left side view of the constitution of the power transmission system of  FIG. 3 . 
       
    
    
     DESCRIPTION OF NUMBERS FOR CONSTITUENTS IN DRAWINGS 
       [0041]      10 : engine  20 : clutch housing 
         [0042]      30 : HST housing  31 : hydro-static transmission (HST) 
         [0043]      40 : mission housing  41 : secondary transmission 
         [0044]      50 : PTO shaft  51 : PTO clutch 
         [0045]      52 : PTO transmission  60 : side brake 
         [0046]      70 : front wheels  80 : rear wheels 
         [0047]      100 : clutch housing  100   a : front 
         [0048]      100   b : back  101 : clutch 
         [0049]      102 : clutch release hub  103 : main shaft 
         [0050]      110 : partition  111 : heat-radiating opening 
         [0051]      112 : filter  120 : guide shaft pipe 
         [0052]      121 : through-hole  130 : molding hole 
         [0053]      131 : rubber cap  140 : mounting block 
         [0054]      150 : assembly hole  151 : finish-cap 
         [0055]      160 : connection hole  200 : HST filter 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0056]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which the preferred embodiment(s) of the invention is shown so that those of ordinary skill in the art can easily carry out the present invention. 
         [0057]    In the description of the present invention, the same numbers as those used in the Prior Art refer to the same elements and the overlapping description will not be presented. 
         [0058]      FIGS. 3 through 7  show the structure of a power transmission system of a tractor according to the present invention. 
         [0059]    As shown in the drawings, the power transmission system to transmit power from an engine  10  to front wheels  70  and rear wheels  80  is positioned at the back of the engine  10 . 
         [0060]    Specifically, as shown in  FIG. 5 , in the power transmission system of the tractor, a clutch  101  is connected to the back of the engine  10 , a HST  31  is connected to the clutch  101 , and a secondary transmission  41  is connected to the HST  31 . 
         [0061]    Therefore, the power of the engine  10  is transmitted to the front wheels  70  and the rear wheels  80  of the tractor through the clutch  101 , the HST  31  and the secondary transmission  41 . 
         [0062]    The clutch  101 , the HST  31  and the secondary transmission  41  are each included in a clutch housing  100  and a mission housing  40 . 
         [0063]    That is, the clutch housing  100  in which the clutch  101  and the HST  31  is positioned at the back of the engine  10 , and the mission housing  40  in which the secondary transmission  41  is included is positioned at, the back of the dutch housing  100 . 
         [0064]    Specifically, the clutch housing  100  includes a partition  110  inside, to isolate a space in the clutch housing  100 . Based on the partition  110 , one side of the clutch housing  100  which is close to the engine  10  is named as a front section  100   a  and the other side is named as a rear section  100   b.    
         [0065]    The clutch  101  to control the transmission of the power which is output from the engine  10  is positioned in the front section  100   a  of the clutch housing  100 , and the HST  31  is positioned in the rear section  100   b.    
         [0066]    A rear end of the clutch housing  100  including the clutch  101  and the HST  31  together is bolted to a front end of the mission housing  40 . 
         [0067]    In the present invention, since the conventional HST housing  30  is not needed, the overall structure of the power transmission system is simple and compact. Further, since the clutch housing  100  is directly bolted to the mission housing  40 , the assembly work is reduced to improve the workability and productivity 
         [0068]    As shown in  FIG. 4 , a heat-radiating opening  111  is formed at an upper part of the partition  110  of the clutch housing  100 , a guide shaft pipe  120  to guide a clutch release hub  102  is formed to protrude at the middle part thereof. 
         [0069]    Specifically, the heat-radiating opening  111  formed at the upper part of the partition  110  is to discharge the heat generated by the operation of the clutch  101  in the front section  100   a  of the clutch housing  100 , where the clutch  101  is positioned, toward the rear section  100   b  of the clutch housing  100  where the HST  31  is positioned. The heat discharged to the rear section  100   b  of the clutch housing  100  is discharged to the outside of the clutch housing  100 , through an assembly hole  150  and a connection hole  160  formed on the outer side of the clutch housing  100 , to be described later. 
         [0070]    The heat-radiating opening  111  is provided with a filter  112  to cover the heat-radiating opening  111 . 
         [0071]    When the pollutants, such as soil, dust, etc., which enter into the rear section  100   b  of the clutch housing  100  through the assembly hole  150  and the connection hole  160 , enter into the front section  100   a  of the clutch housing  100  through the heat-radiating opening  111 , since the filter  112  positioned at the heat-radiating opening  111  collectively filters the pollutants contained in the air, the clutch  101  is prevented from being contaminated and therefore it is possible to prevent the malfunction of the clutch  101 . 
         [0072]    The filter  112  positioned at the heat-radiating opening  111  may be a HEPA filter with a high-efficiency collecting function capable of filtering pollutants such as particulate dust contained in the air. 
         [0073]    As shown in  FIG. 5 , the guide shaft pipe  120  under the heat-radiating opening  111  is a hollow pipe with a through-hole  121  which is formed in an axial direction parallel to the center line of the clutch housing  100 . The guide shaft pipe  120  is integrally formed to protrude from the partition  110 . 
         [0074]    A main shaft  103  which is connected to the engine  10  and outputs the power of the engine  10  is provided through the through-hole  121  of the guide shaft pipe  120 . The clutch release hub  102  to connect or separate a disk of the clutch  101  is fitted around the outer side of the guide shaft pipe  120 . The clutch release hub  102  moves back and forth in a straight line on the outer side of the guide shaft pipe  120 , by a transmission rod as a driver works a transmission pedal. 
         [0075]    Specifically, since the main shaft  103  where the power of the engine is output is provided to pass through the through-hole  121  of the guide shaft pipe  120 , it transmits the power of the engine  10  to the front wheels  70  and the rear wheels  80  stably without any interference with the clutch release hub  102 . Since the clutch release hub  102  is fitted about the outer side of the guide shaft pipe  120 , it smoothly operates the clutch  101  without any interference with the main shaft  103 . 
         [0076]    A molding hole  130  is formed under the guide shaft pipe  120  in the partition  110 . The molding hole  130  is unavoidably formed by a core made in a cast in which molten metal is poured upon cast-molding the clutch housing  100 . The molding hole  130  is closed in a state of firmly maintaining airtight and watertight by connecting a rubber cap  131  to the molding hole  130 . 
         [0077]    Therefore, it is possible to prevent the oil supplied to the HST  31  from leaking through the molding hole  130  and to minimize a damage caused by flooding of the clutch housing  100 . 
         [0078]    As shown in  FIGS. 3 and 6 , a mounting block  140  with an oil passage through which the oil enters and exits is integrally formed on the outer side of the clutch housing  100 . An HST filter  200  is mounted on the mounting block  140 , to filter the oil provided to the HST  31  to supply the filtered oil to the HST  31 . 
         [0079]    Specifically, since the mounting block  140  with the HST filter  200  is integrally formed to be included at the outer side of the rear section  100   b  of the clutch housing  100 , the structure of the clutch housing  100  is compact. 
         [0080]    The assembly hole  150  for access to connect the main shaft  103  and the input shaft of the HST  31  is formed at the outer side of the rear section  100   b  of the clutch housing  100  in the front of the HST filter  200 . It is preferable to form the assembly hole  150  with a size permitting the hand of an operator to enter/exit. 
         [0081]    Accordingly, since the operator can insert his/her hand into the clutch housing  100  through the assembly hole  150 , the main shaft  103  and the input shaft of the HST  31  are easily connected, to improve the assembly and maintenance. 
         [0082]    In addition, since the pollutants may enter through the assembly hole  150 , it is preferable to close the assembly hole  150  with a finish cap  151  after connecting the main shaft  103  and the HST  31 . The finish cap  151  may be formed of a rubber material which is excellent in airtight and watertight attributes. 
         [0083]    When the assembly hole  150  is used (including when the heat is radiated), the finish cap  151  is separated from the assembly hole  150 . After the assembly hole  150  is used, the finish cap  151  is connected to the assembly hole  150  for closure of the opening. 
         [0084]    As shown in  FIG. 7 , the connection hole  160  to connect an operation lever of the HST  31  is formed at the outer side of the clutch housing  100  opposite to that where the assembly hole  150  is positioned. 
         [0085]    The connection hole  160  is provided with a cap of a rubber material, which does not interrupt the operation lever of the HST  31 , thereby minimizing exposure by sealing the connection hole  160 . 
         [0086]    In the power transmission system of the tractor according to the present invention, since the clutch  101  is included in the front section  100   a  of the clutch housing  100  and the HST  31  is included in the rear section  100   b  of the clutch housing  100 , the clutch  101  and the HST  31  are all included in one clutch housing  100 , enabling a simple and compact structure of the power transmission system and reducing the number of parts to lower the cost of production. 
         [0087]    Since the partition  110  is formed to separate the clutch  101  from the HST  31  inside the clutch housing  100  and the heat-radiating opening  111  is formed in the partition  110 , the clutch  101  is prevented from being contaminated and the heat generated by the clutch  101  is discharged to the outside of the clutch housing  100  through the heat-radiating opening  111 , the assembly hole  150  and the connection hole  160 . 
         [0088]    Further, since the filter  112  which is a HEPA filter is provided to the heat-radiating opening  111  of the partition  110 , the pollutants are prevented from penetrating into the front section  100   a  of the clutch housing  100  where the clutch  101  is included, to prevent the contamination of the clutch  101 . 
         [0089]    Further, since the mounting block  140  to mount the HST filter  200  is integrally formed to be included at the outer side of the clutch housing  100 , the outside structure of the clutch housing  100  is compact. 
         [0090]    The invention has been described using preferred exemplary embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, the scope of the invention is intended to include various modifications and alternative arrangements within the capabilities of persons skilled in the art using presently known or future technologies and equivalents. 
         [0091]    Simple modifications or similar arrangements of the present invention belong to the category of the invention and therefore, the protection range of the invention will be apparent by the claims attached herewith.