JP3192095B2 - Riding lawn mower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle equipped with an engine mounted on a front portion of a traveling body, and having a dust-proof external air intake at a lower portion of a control panel surrounding a steering handle shaft provided upright behind the engine. And a cooling air passage for flowing cooling air from the outside air intake toward the engine.

[0002]

2. Description of the Related Art There are two types of riding lawn mowers having a hydraulic system for elevating and lowering a mower, and models having no hydraulic system for elevating and lowering a mower. When the former model is equipped with a power steering device that supplies steering assist force, a hydraulic type that can effectively use the hydraulic system for elevating and lowering the mower is used in order to simplify the configuration and reduce manufacturing costs. It is possible to adopt. On the other hand, when the latter model is equipped with a power steering device, if a hydraulic type is adopted as in the former model, a complete set of hydraulic systems (hydraulic pumps, hydraulic piping, etc.) must be newly installed. This causes inconveniences such as a complicated configuration and an increase in manufacturing cost. Therefore, conventionally, when the latter type is equipped with a power steering device, it is conceivable to adopt an electric type that can simplify the configuration and reduce the manufacturing cost as compared with a hydraulic type. I was By the way,
The electric power steering device includes an assist electric motor, a torque sensor that detects an operation torque at the time of steering operation, and a control device that controls the operation of the electric motor based on the detection from the torque sensor. .

[0003]

However, in the electric power steering apparatus, a large electric current flows during operation to generate heat in the electric motor and the control apparatus during operation. Due to its function, the frequency of turning is high and the turning is often performed at low speed or with a small radius, and when a power steering device is equipped, the burden on it becomes large. For this reason, when an electric power steering device is mounted on a riding lawn mower as in the prior art described above, the temperature of the heat generated by the electric motor and the control device rises remarkably, causing inconvenience and control of the electric motor. There is a possibility that the device may be damaged.

[0004] It is an object of the present invention to increase the heat generation temperature of an electric motor and a control device during its operation while employing an electric power steering device capable of simplifying the structure and reducing the manufacturing cost. An object of the present invention is to prevent the burn-in of the electric motor and the damage of the control element caused by the electric motor.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, an engine is mounted on a front portion of a traveling body and is provided upright behind the engine. A riding lawn mower having a dustproof structure outside air intake provided below a control panel surrounding a steering handle shaft and forming a cooling air passage from the outside air intake toward the engine. ,
An electric power steering device that supplies a steering assist force controls an operation of the electric motor based on detection from an electric motor for assist in the power steering device and a torque sensor that detects an operation torque at the time of steering operation. And a control device to be located in the cooling air passage.

According to the first aspect of the present invention, during operation, the electric motor and the control device of the power steering device are constantly cooled by being exposed to the cooling air flowing from the outside air intake of the control panel toward the engine. Accordingly, it is possible to suppress an increase in the heat generation temperature of the electric motor and the control device during the operation of the power steering device. Further, since the outside air intake has a dustproof structure, it is possible to prevent dust such as mowing turf generated at the time of lawn mowing work from being taken in with the outside air and adversely affecting the electric motor, the control device or the engine. Become like

Accordingly, while employing an electric power steering device capable of simplifying the configuration and reducing the manufacturing cost, the electric motor caused by the rise in the heat generated by the electric motor and the control device during its operation is increased. Of the control element and breakage of the control element can be avoided.

According to the second aspect of the present invention,
The invention according to claim 1, wherein the steering support base for supporting the steering handle shaft is provided with an auxiliary cooling air passage having a dustproof structure for taking in auxiliary cooling air from an opening formed at the bottom thereof and flowing into the cooling air passage. Was.

According to the second aspect of the present invention, the auxiliary cooling air is introduced from the opening formed in the bottom of the steering support base through the auxiliary cooling air passage, and the cooling air flows through the electric motor and the control device of the power steering device. When the electric motor and the control device are provided so as to flow into the road, the electric motor and the control device can be exposed to the auxiliary cooling wind, and the electric motor and the control device can be more appropriately cooled. It is possible to suppress an increase in the heat generation temperature of the electric motor and the control device during the operation of. Further, when the auxiliary cooling air path is provided so that the auxiliary cooling air introduced from the opening formed at the bottom of the steering support base flows into the cooling air path without passing through the electric motor or the control device of the power steering device. Can more suitably cool the engine, so that it is possible to prevent the heat generation temperature of the electric motor or the control device from indirectly increasing due to the influence of radiant heat from the engine. In addition, since the auxiliary cooling air passage has a dust-proof structure, it prevents dust such as mowing turf generated during lawn mowing work from being taken in with the outside air and adversely affecting the electric motor, the control device or the engine. become able to.

Therefore, it is possible to more reliably avoid burn-in of the electric motor and breakage of the control element due to an increase in the heat generation temperature of the electric motor and the control device during the operation of the power steering device, and to generate heat of the electric motor and the control device. It has become possible to suppress a decrease in conductivity with an increase in temperature.

[0011] In the invention according to claim 3 of the present invention,
In the second aspect of the present invention, a battery for supplying power to the power steering device is provided so as to be located in the auxiliary cooling air passage.

According to the third aspect of the present invention, during operation, the battery is exposed to the auxiliary cooling air taken in from the opening formed in the bottom of the steering support and is cooled. In addition to suppressing the rise in temperature, it is possible to prevent the heat generation temperature of the electric motor and the control device from increasing indirectly due to the influence of radiant heat from the battery.

Therefore, it is possible to more reliably avoid burn-in of the electric motor and breakage of the control element due to an increase in the heating temperature of the electric motor and the control device during operation of the power steering device. This has made it possible to suppress a decrease in the electrical conductivity due to an increase in the heat generation temperature.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall side view of a riding lawn mower. This riding lawn mower includes a riding traveling body 1 and
A mid-mount type is formed by a mower 4 suspended and supported in a parallel quadruple link manner by a front link 2 and a rear link 3 at the front and rear intermediate position. The traveling body 1
A body frame 5 including a pair of left and right main frames 5A and the like, a horizontal axis type engine 6 mounted on a front part of the body frame 5, a cooling fan 7 mounted on the back of the engine 6, and a rear part of the cooling fan 7 are provided. A radiator 8, a hydrostatic continuously variable transmission 9 connected to a rear part of the body frame 5, an axle frame 10 connected to a lower front part of the body frame 5,
An axle case 11 connected to the lower rear of the body frame 5;
A front wheel 12 as a steering wheel mounted on each of the left and right ends of the axle frame 10, a rear wheel 13 as a drive wheel mounted on each of the left and right ends of the axle case 11, a steering handle 14 linked to the front wheel 12, and It is composed of a driver seat 15 arranged above the rear part of the body frame 5 and the like.

As shown in FIGS. 1 and 2, a transmission case 16 incorporating a bevel gear type transmission mechanism (not shown) is provided in front of the axle case 11 in the body frame 5. The transmission case 16 is operatively connected to the engine 6 via a transmission shaft 17 extending forward from a front portion thereof. A first output pulley 1, which is operatively connected to an input pulley 9 a of the hydrostatic continuously variable transmission 9 via a first transmission belt 18, is provided above the transmission case 16.
6a, and a power supply for supplying power to a blower device (not shown) for flowing cut grass from the mower 4 toward the grass collection container when the grass collection container (not shown) is attached to the rear portion of the traveling body 1. The second output pulley 16b is vertically arranged side by side. On the other hand, a third output pulley 16 c, which is operatively connected to the input pulley 4 a of the mower 4 via a second transmission belt 19, is mounted below the transmission case 16 via an electromagnetic clutch 20.

As shown in FIGS. 1, 3 and 4, a pair of left and right front wheels 12 and a steering handle 14 are provided with knuckle arms 21 mounted on the left and right front wheels 12, respectively.
A tie rod 22 interlockingly connecting the left and right knuckle arms 21, a front-rear drag link 23 interlockingly connected to the left knuckle arm 21, and a drag link 2.
3 and a steering wheel shaft 24 extending downward from the steering handle 14 and are linked by a rack and pinion type transmission mechanism 25 for interlocking connection. The transmission mechanism 25 is provided outside the main frame 5A on the left side of the body frame 5 in a front-back posture along the main frame 5A. Therefore, the steering handle shaft 24
Is equipped with a universal joint 24a for displacing the lower side toward the transmission mechanism 25. According to the above configuration, when the turning operation of the steering handle 14 is performed, the steering handle shaft 24 is accordingly operated to rotate, and the pinion (not shown) of the transmission mechanism 25 linked to the lower end thereof is A rack (not shown) of the transmission mechanism 25 linked to the drag link 23 is moved in the front-rear direction. As a result, the left side including the left knuckle arm 21 linked to the drag link 23 is provided. Right knuckle arm 2 operatively connected to a front knuckle arm 21 via a tie rod 22 and a left knuckle arm 21.
The right front wheel 12 provided with the steering wheel 1 is steered so that a steering angle (turning angle) corresponding to the amount of turning operation of the steering handle 14 is obtained.

The relationship between the steering operation amount of the steering wheel 14 and the steering angle of the front wheels 12 will be described in detail. The pitch of the meshing teeth in the rack and the pinion is set to be unequal so that the relationship draws the characteristic curve shown in FIG. In other words, the transmission mechanism 25 reduces the amount of change in the steering angle of the front wheels 12 as the amount of turning operation of the steering handle 14 from the straight traveling position (neutral position) decreases (the steering handle 1).
4 is set such that the larger the amount of turning operation from the straight traveling position, the larger the amount of change in the steering angle of the front wheel 12). Even if the steering handle 14 slightly shakes due to, for example, the steering angle of the front wheels 12 can be suppressed from changing due to the shake, the traveling body 1 can be easily maintained in a straight-ahead state, and thus the straight-ahead running can be achieved. Beautiful mowing marks can be easily obtained.

As shown in FIGS. 1, 3 and 4, the engine 6 and the radiator 8 arranged at the front of the traveling body 1 are covered with an engine bonnet 26, and are disposed substantially at the center of the traveling body 1. The upright steering handle shaft 24 is surrounded from the back by a control panel 27 formed to be continuous with the engine bonnet 26. An outside air intake 27A into which outside air is taken in with the rotation of the cooling fan 7 is formed at a lower portion of the control panel 27. This outside air intake 27
A has a dustproof structure in which a dustproof net 28 is stretched, and prevents dust such as cut grass from being taken in from the outside air intake 27A together with the outside air during a lawn mowing operation. A mounting table 29 is provided at a portion of the body frame 5 from the radiator 8 to the control panel 27 so as to close the portion.
A box-shaped steering support 30 that supports the steering handle shaft 24 is connected to the rear side of 9. That is, the engine hood 26, the control panel 27, and the mounting table 29 allow the cooling air path R to flow cooling air (outside air) from the outside air intake 27 </ b> A toward the radiator 8 and the engine 6 as the cooling fan 7 rotates. Are formed.

As shown in FIGS. 1, 3, 4 and 6, a pair of left and right front wheels 12
Is equipped with an electric power steering device PS. The power steering device PS is based on a torque sensor 31 mounted on a steering handle shaft 24, an electric motor 33 for supplying a steering assist force to the steering handle shaft 24 via a bevel gear mechanism 32, and detection from the torque sensor 31. And a control device 34 for controlling the operation of the electric motor 33. The torque sensor 31 detects an operation torque acting on the steering handle shaft 24 in accordance with the turning operation of the steering handle 14, and based on the detection, Control device 34 is an electric motor 33
And the power (steering assist force) obtained by the operation is transmitted to the steering handle shaft 24 via the bevel gear mechanism 32.
The steering handle shaft 24 is assistedly rotated by the steering assist force from the electric motor 33. That is, the turning operation force of the steering handle 14 during the steering operation can be reduced.

As shown in FIGS. 1, 3 and 4, the electric motor 33 of the power steering device PS is connected to the steering handle shaft 24 at an upper and lower intermediate portion. Further, the control device 34 is connected and provided on the left side of the steering support base 30. In other words, the electric motor 33 and the control device 34 of the power steering device PS are arranged so as to be located in the cooling air passage R, so that the electric motor 33 of the power steering device PS is always in operation while the cooling fan 7 is operating. And the control device 34 can be cooled by being exposed to the cooling air flowing toward the engine 6 from the outside air intake 27A of the control panel 27, so that the electric motor 33 and the control device 34 during the operation of the power steering device PS. Of the electric motor 33 during operation of the power steering device PS, and to prevent burn-in of the electric motor 33 and breakage of the control element due to the increase in the heat generation temperature of the electric motor 33 and the control device 34. Has become. Also, by disposing the electric motor 33 and the control device 34 of the power steering device PS in the cooling air passage R formed by the engine hood 26, the control panel 27, and the mounting table 29, Water can be prevented from directly splashing, and even if water adheres to these electric systems, they can be blown off by cooling air, so that the waterproofing of the power steering device PS can be advantageously performed. I have. Moreover, the outside air intake 27
A has a dustproof structure, so that dust such as mowing turf generated during mowing work is taken in together with the outside air, and the electric motor 33 and the control device 34 of the power steering device PS.
Alternatively, it is possible to prevent adverse effects on the engine 6 and the like.

As shown in FIG. 3 and FIG.
An opening 30A is formed at the bottom of the steering support base 30 continuously provided on the rear side, and the front wall is formed of a dustproof net 30B. That is, the steering support 30 has an opening 30A formed at the bottom thereof.
An auxiliary cooling air passage r of a dustproof structure is provided to take in the auxiliary cooling air from the inlet and flow into the cooling air passage R. A battery 35 for supplying power to the power steering device PS and the like is provided at a position immediately before the dustproof net 30B of the steering support base 30 on the mounting table 29 in the auxiliary cooling air path r.
Has been deployed. That is, since the battery 35 is located in the auxiliary cooling air path r, the battery 35 can be exposed to the auxiliary cooling air taken in from the opening 30A formed at the bottom of the steering support base 30 during the operation of the cooling fan 7. As a result, the temperature of the battery 35 can be suppressed from rising, and the power steering device P can be indirectly affected by the radiant heat from the battery 35.
The heat generation temperature of the electric motor 33 of S and the control device 34 can be prevented from rising. As a result, the electric motor 3 during the operation of the power steering device PS
3 and the control device 34 can more reliably avoid burn-in of the electric motor 33 and breakage of the control element due to an increase in the heat generation temperature of the control device 34.
In addition, it is possible to suppress a decrease in conductivity due to an increase in the heat generation temperature of the battery 35.

Further, since the power steering device PS and the battery 35 can be arranged close to each other while improving the cooling efficiency, the wiring of the harness can be simplified and shortened over them, so that the power steering device PS is provided. The configuration described above can be simplified, and a voltage drop between the battery 35 and the power steering device PS can be suppressed. Moreover, since the auxiliary cooling air passage r has a dustproof structure, dust such as mowing turf generated during lawn mowing work is taken in together with the outside air and adversely affects the electric motor 33, the control device 34, the engine 6, and the like of the power steering device PS. Can be prevented. Furthermore, since the dustproof net 30B is provided on the front wall portion of the steering support base 30 that is deeper than the bottom opening 30A,
As compared with the case where the dustproof net 30B is provided in the bottom opening 30A, dust such as cut grass is less likely to adhere to the dustproof net 30B, and since the dustproof net 30B is in a vertical posture, the cut grass is attached to the dustproof net 30B. Even if the dust adheres, most of the dust naturally falls as the cooling fan 7 stops, so that the clogging of the dustproof net 30B due to dust such as cut grass can be suppressed.

As shown in FIGS. 1, 3 and 4, the electric motor 33 of the power steering device PS is inclined rightward and forward from the steering handle shaft 24 or inclined leftward and forward (in this embodiment, The attitude toward the front diagonally right is illustrated, and the attitude toward the front diagonally left is omitted. By arranging the electric motor 33 in this manner, the electric motor 33
The electric motor 33 is viewed in a plan view without the inconvenience that the boarding space of the traveling body 1 is narrowed, as in the case where the In this case, the battery 35 can be disposed so as not to overlap with the battery 35, so that replacement and maintenance of the battery 35 can be easily performed without being hindered by the electric motor 33.

As shown in FIG. 6, the traveling body 1 has a clutch sensor 36 for detecting the operating state of the mower 4 from a state of energization of the electromagnetic clutch 20 and a steering angle detection sensor for detecting the steering angle of the front wheels 12. 37, and a steering sensor 38 for detecting the operation direction of the steering handle 14 are provided. The control device 34 of the power steering device PS receives detection information from each of the sensors 36 to 38, and The control device 34 controls the operation of the electric motor 33 based on the detected information to adjust the steering assist force output from the electric motor 33. More specifically, as shown in FIG. 7, the control device 34 controls the steering speed to be higher during non-operation traveling when the electromagnetic clutch 20 is detected to be in the non-transmission state by the clutch sensor 36 than during operation traveling. Since the operation can be performed relatively lightly, the operation of the electric motor 33 is controlled so that the steering assist force output from the electric motor 33 becomes “medium”. Further, during work traveling in which the clutch sensor 36 detects that the electromagnetic clutch 20 is in the transmission state, first, the steering angle of the front wheel 12 detected by the steering angle detection sensor 37 is ± Fifteen
°, it is determined that the vehicle is traveling straight, and the steering assist force output from the electric motor 33 is set to “minimum”. The operation of is controlled.
That is, during the mowing work by traveling straight ahead, the steering assist force from the electric motor 33 is set to “minimum”.
In addition, by increasing the steering and increasing the straightness, it is possible to prevent the handle from being taken off by the influence of the unevenness and inclination of the work place and to prevent the machine from fluttering. Preventing. on the other hand,
When the steering angle of the front wheel 12 detected by the steering angle detection sensor 37 is not within the range of ± 15 ° with the straight traveling position set to 0 °, it is determined that the vehicle is turning, and the steering sensor 38 detects this. Steering handle 14
Check the turning direction from the operation direction of. Turning direction is "left"
When the turning direction is the right direction, the operation of the electric motor 33 is controlled so that the steering assist force output from the electric motor 33 becomes “maximum”, and when the turning direction is the “right” direction, , The electric motor 3 so that the steering assist force output from the electric motor 33 becomes “medium”.
3 is controlled. That is, in the riding lawn mower, generally, the mower 4 is offset to the left with respect to the traveling body 1 and an opening (not shown) for mowing turf discharge is provided at the right end of the mower 4, so that the work mower 4 Since it is configured to change the direction by turning left, the electric motor 33 is turned at the time of turning left during work traveling.
The steering assist force from the motor 33 is set to “maximum”, the steering is lightened so that the steering operation to the left can be easily performed, and the steering assist force from the electric motor 33 during the right turn during the work traveling. Is set to "medium", and the steering is made relatively heavy, so that it is difficult to perform the steering operation to the right.

In place of the clutch sensor 36, a lever sensor (not shown) for detecting the operating position of the operating lever 39 for manually lifting and lowering the mower 4 is provided, and the operating lever detected by this lever sensor is provided. The control device 34 may be configured to detect the operating state of the mower 4 from the operating position 39 (elevation height of the mower 4), and either the steering angle detection sensor 37 or the steering sensor 38 Alternatively, the steering angle of the front wheel 12 (the steering angle of the steering wheel 14) and the operating direction of the steering handle 14 (the steering direction of the front wheel 12) may be detected.

Further, as the traveling speed increases, the steering becomes lighter, and as described above, the transmission mechanism 25
Is set such that the larger the amount of turning operation (operation angle) of the steering wheel 14 from the straight traveling position becomes, the larger the amount of change in the steering angle of the front wheel 12 becomes. As shown in the figure, a vehicle speed sensor 40 for detecting the traveling speed and a steering operation angle detection sensor 41 for detecting the operation angle of the steering wheel 14 are provided. During work traveling, the control device 34 controls the vehicle speed as shown in FIG. The operation of the electric motor 33 may be controlled based on detection information from the sensor 40 and the steering operation angle detection sensor 41 to adjust the steering assist force output from the electric motor 33. More specifically, the traveling speed detected by the vehicle speed sensor 40 is 4 km.
/ H or less, since the steering is sufficiently heavy, regardless of the operation angle of the steering wheel 14 detected by the steering operation angle detection sensor 41,
The operation of the electric motor 33 is controlled so that the steering assist force output from the electric motor 33 becomes “maximum”. The traveling speed detected by the vehicle speed sensor 40 is 4 km
/ H to 5 km / h, since the steering is relatively heavy, the steering operation angle detection sensor 41
Until the operation angle of the steering handle 14 detected by the control reaches the predetermined operation angle θa set in advance, the operation of the electric motor 33 is controlled so that the steering assist force output from the electric motor 33 becomes “maximum”. Control the
The operation angle of the steering handle 14 is a predetermined operation angle θa
As described above, the operation of the electric motor 33 is controlled such that the steering assist force output from the electric motor 33 with a large change amount becomes smaller (the steering becomes heavier) as the operation angle of the steering handle 14 becomes larger.
The traveling speed detected by the vehicle speed sensor 40 is 5 km / h
In this case, the electric motor 3
3. The starting point of the above-described control operation in which the steering assist force output from 3 becomes smaller (the steering becomes heavier) and the steering assist force becomes smaller (the steering becomes heavier) with a larger change amount as the operation angle of the steering handle 14 becomes larger. Steering handle 14
The control device 34 is configured to control the operation of the electric motor 33 so that the predetermined operation angle θa becomes smaller (the start of the above-described control operation becomes faster). That is, the operation of the electric motor 33 is controlled so that the steering becomes heavier as the traveling speed becomes faster and the operation angle of the steering handle 14 becomes larger. This prevents the grass from being damaged by turning.

In this case, instead of the steering operation angle detection sensor 41, a steering angle detection sensor 37 for detecting the steering angle of the front wheel 12 and a steering sensor for detecting the operation angle of the steering wheel 14 are used. 38 may be adopted.

[Other Embodiments] Hereinafter, other embodiments of the present invention will be listed. In the above embodiment, the horizontal axis type engine 6 is mounted on the front part of the body frame 5, and the cooling fan 7 and the radiator 8 are provided behind the engine 6,
Further, a control panel 27 erected behind the radiator 8 is provided.
Is formed at the lower part of the airframe, the traveling body 1 having the cooling air path R formed so that the cooling air flowing from the outside air intake 27A toward the radiator 8 flows linearly along the longitudinal direction of the body. As illustrated in FIG. 9, as the traveling body 1, as shown in FIG. 9, a longitudinal axis type engine 6 is mounted on a front part of a body frame 5, and a cooling fan 7 and a radiator 8 are provided above the engine 6. And a control panel 2 erected behind the engine 6.
7, a cooling air passage R is formed so that cooling air flowing from the outside air intake 27A toward the radiator 8 flows upward from the lower part of the body toward the upper front thereof. It may be something. In the above embodiment, the front-wheel steering traveling body 1 is used.
However, as the traveling body 1, a rear-wheel steering type in which a steering wheel 14 is linked to a rear wheel 13,
The steering wheel 14 may be of a four-wheel steering type in which the front wheel 12 and the rear wheel 13 are linked. As shown in FIG. 10, the power steering device PS
May be disposed so as to be located in the cooling air passage R while being integrally formed with the rack and pinion type transmission mechanism 25. According to this configuration, the relatively heavy electric motor 33 can be arranged at the lower part of the traveling body 1 and the body weight can be lowered, so that the stability of the traveling body 1 can be improved, and the electric motor 33 can be improved. And transmission mechanism 2
5, the structure can be simplified and the manufacturing cost can be reduced. The ceiling of the steering support 30 is formed of a dustproof net 30B so that the electric motor 33 of the power steering device PS is also positioned in the auxiliary cooling air path r, and the electric power of the power steering device PS can be more effectively driven. Motor 3
3 may be allowed to cool. Further, the left wall of the steering support 30 is formed of a dust-proof net 30B so that the control device 34 of the power steering device PS is also located in the auxiliary cooling air path r, so that the power steering device can be more effectively used. The control device 34 of the PS may be allowed to cool. By employing a punching metal or the like instead of the dustproof net 30B, the auxiliary cooling air passage r may be configured to have a dustproof structure.

[Brief description of the drawings]

FIG. 1 is an overall side view of a riding lawn mower.

FIG. 2 is a plan view of a riding lawn mower showing a transmission structure.

FIG. 3 is a longitudinal sectional side view of a main part of a riding lawn mower showing an arrangement of a power steering device and a battery.

FIG. 4 is a cross-sectional plan view of a front half of a riding lawn mower showing an arrangement of a power steering device and a battery.

FIG. 5 is a diagram illustrating a relationship between a steering operation amount of a steering wheel set by a transmission mechanism and a steering angle of a front wheel.

FIG. 6 is a block diagram showing a control configuration of the power steering device.

FIG. 7 is a flowchart showing control for adjusting a steering assist force based on a running state by the control device;

FIG. 8 is a diagram showing how a control device adjusts a steering assist force based on a traveling speed and a steering operation angle.

FIG. 9 is a longitudinal sectional side view showing the configuration of the first half of a riding lawn mower according to another embodiment.

FIG. 10 is a diagram showing a location of an electric motor according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traveling body 6 Engine 24 Steering handle shaft 27 Control panel 27A Outside air intake 30 Steering support 30A Opening 31 Torque sensor 33 Electric motor 34 Control device 35 Battery PS Power steering device R Cooling air path r Auxiliary cooling air path

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masatoshi Yamaguchi 64 Ishizukita-cho, Sakai City, Osaka Prefecture Inside Kubota Sakai Works Co., Ltd. (72) Inventor Masaki 64 Ishizukita-machi Sakai City, Osaka Prefecture Kubota Sakai Manufacturing Co., Ltd. In-house (72) Inventor Kazuaki Kurohara 64 Ishizukita-cho, Sakai City, Osaka Prefecture Inside Kubota Sakai Factory Co., Ltd. (72) Inventor Shogo Murakawa 64-Ishizukita-machi Sakai City, Osaka Prefecture Kubota Sakai Factory Co., Ltd. (72) Invention Person Hiroki Nagai 64 Ishizukita-cho, Sakai City, Osaka Prefecture (72) Inside the Kubota Sakai Works, Ltd. (72) Inventor Yoshio Toyama 64 Ishizukitamachi, Sakai City, Osaka Prefecture, Ltd. 64 Ishizu-Kitacho, Ishizu-shi Kubota Corporation Sakai Factory (72) Inventor Katsuhiko Uemura 64 Ishizu-Kitacho, Sakai-shi, Osaka Kubota Corporation In-house (56) References JP-A-4-71928 (JP, A) JP-A-5-284803 (JP, A) JP-A 55-95969 (JP, U) JP-A 56-172425 (JP, U (58) Fields surveyed (Int.Cl. ⁷ , DB name) B62D 5/04-5/06 B62D 6/00-6/02 F01P 5/00-5/06

Claims (3)

(57) [Claims] An engine is mounted on a front part of a traveling body, and an outside air intake having a dustproof structure is provided at a lower portion of a control panel surrounding a steering handle shaft provided upright behind the engine. In a riding lawn mower having a cooling air passage for flowing cooling air from an intake port to the engine, an electric power steering device for supplying a steering assist force is provided by an electric motor for assist in the power steering device. A riding lawn mower in which a motor and a control device that controls the operation of the electric motor based on a detection from a torque sensor that detects an operating torque at the time of steering operation are disposed so as to be located in the cooling air path. . 2. An auxiliary cooling air passage having a dust-proof structure for taking in auxiliary cooling air from an opening formed in a bottom portion thereof and flowing into the cooling air passage on a steering support base supporting the steering handle shaft. 1. The riding lawn mower according to 1. 3. The riding lawn mower according to claim 2, wherein a battery for supplying electric power to said power steering device is disposed in said auxiliary cooling air passage.