Patent Description:
A lawn mower is a common garden tool, and a traditional self-propelled lawn mower realizes self-propelled function by driving a front wheel or a rear wheel thereof through a speed reducer. When the self-propelled lawn mower needs to climb a slope during mowing grasses, a speed thereof will decrease or even the self-propelled lawn mower will stop. The reason for this is that a load of the self-propelled lawn mower becomes larger during climbing the slope, and a power of a self-propelled motor of the self-propelled lawn mower cannot meet the requirements for the load. However, if the power of the self-propelled motor of the self-propelled lawn mower is merely increased, when the self-propelled lawn mower travels on a flat ground, a required power for the self-propelled motor will be lower, and thus a maximum efficiency ratio of the self-propelled motor will not be achieved, thereby resulting in excessive loss and waste of energy.

<CIT> discloses a power tool, a grass mower and a method for controlling the grass mower. The grass mower comprises blades for mowing grass, a chassis for receiving the blades, front wheels rotatably connected on the front side of the chassis, rear wheels rotatably connected on the rear side of the chassis, a motor at least for driving the rear wheels to rotate, a detection device for detecting the rotational speed of the front wheels, and a controller for decreasing the speed of the motor when the rotational speed of the front wheels is decreased, wherein the motor is connected to the rear wheels and the detection device is electrically connected to the controller. The grass mower controls the travelling speed of the grass mower by detecting the speed of the front wheels.

<CIT> discloses a lawn mower comprising: a casing, a locomotion mechanism, which comprises drive wheels, a motor to drive rotation of the drive wheels and a control device preconfigured with a first torque threshold and a second torque threshold. During a process of starting the motor from a stopped state to an operational state, the control device limits the difference between a maximum actual output torque and the first torque threshold to within a preconfigured range. When the motor is in an operational state, the control device limits the maximum increase of the actual output torque of at least one motor to within a second torque threshold. The invention thereby prevents the drive wheels from overcoming resistance and rotating, prevents the drive wheels from rotating during a collision, and prevents lawn abrasion.

In view of this, it is required to provide an improved lawn mower to solve the above problems.

An objective of the disclosure is to provide a lawn mower with good energy saving effect and convenient operation.

In order to achieve the above objective, a lawn mower is provided according to claim <NUM>.

The disclosure has following beneficial effects. For the lawn mower of the disclosure, the first control element is set to control the turning-on or turning-off of the first self-propelled motor, and the second control element is set to control the turning-on or turning-off of the second self-propelled motor, such that when the operation requirements can be met by driving a single self-propelled motor, only the first self-propelled motor is controlled to operate; while when the operation requirements cannot be met by driving a single self-propelled motor, the second self-propelled motor is further controlled to operate to realize four-wheel drive. Moreover, the first self-propelled motor and the second self-propelled motor may be separately controlled, therefore, the effect of saving energy is not only achieved, but it is also convenient for operation and maintenance.

In order to make objects, technical solutions and advantages of the disclosure clearer, the disclosure will be described in detail with reference to accompanying drawings and specific embodiments.

Referring to <FIG>, the disclosure provides a self-propelled lawn mower <NUM>. The lawn mower <NUM> includes a housing <NUM>, a push rod <NUM> connected to the housing <NUM>, a traveling wheel supported the lawn mower <NUM>, a self-propelled motor which is configured to drive the traveling wheel to self-propel, a control circuit board <NUM> which is configured to control turning-on and turning-off of the self-propelled motor and an enclosure which is assembled with the housing <NUM> (not shown).

A blade and a motor for driving the blade to rotate are arranged in the housing <NUM>, a power assembly <NUM> is formed by the blade and the motor. The blade arranged at the bottom of the housing <NUM> is rotatable along a rotating shaft perpendicular to a ground to mow grasses on the ground. A power supply assembly (not shown) is also arranged in the housing <NUM>, and the power supply assembly is configured to supply power to the lawn mower <NUM> to ensure that the grasses are mowed effectively.

The push rod <NUM> is U-shaped and include a first handle <NUM>, a second handle <NUM>, and a third handle <NUM>. Specifically, the first handle <NUM> extends backward and upward along a rear portion of the housing <NUM>, the third handle <NUM> is connected with the first handle <NUM> and the second handle <NUM>, and the third handle <NUM> is located at the top of the push rod <NUM>, such that an operator may stand behind the push rod <NUM> and grasp the third handle <NUM> of the push rod <NUM> to thereby operate the lawn mower <NUM>. The first handle <NUM>, the second handle <NUM> and the third handle <NUM> may be integrally formed, and may also be assembled and connected, which is not limited herein, as long as it is convenient to operate the lawn mower <NUM>.

The first handle <NUM> and the second handle <NUM> are each provided with a folding structure <NUM>, and the folding structure <NUM> is configured to adjust an angle of the push rod <NUM>, thereby facilitating folding of the lawn mower <NUM>. The housing <NUM> is also provided with a height adjustment assembly <NUM> for adjusting a height between the housing <NUM> and the ground to thereby adjust a mowing height.

A main knife switch box <NUM> is arranged a position on the second handle <NUM> close to the third handle <NUM>. A turning-on switch (not shown), a turning-on button <NUM> and a return spring (not shown) are arranged in the main knife switch box <NUM>. The turning-on switch is connected with the motor for turning-on the motor. The lawn mower <NUM> further includes a main knife switch pull rod <NUM> arranged close to the third handle <NUM>, and the main knife switch pull rod <NUM> is arranged above the main knife switch box <NUM> and connected with the turning-on switch.

In a case that the blade of the lawn mower <NUM> is required to be turned-on, the turning-on button <NUM> is first pressed, the main knife switch pull rod <NUM> is then pulled to thereby enable the main knife switch pull rod <NUM> to fit with the third handle <NUM>, enable the main knife switch pull rod <NUM> to pull the turning-on switch to turn-on the motor and drive the blade to rotate for performing a mowing process. In a case that the mowing process is finished, the main knife switch pull rod <NUM> is released, and the main knife switch pull rod <NUM> is restored to an initial position under the action of the return spring, and then the turning-on switch is turned-off and the blade stops rotating.

In order to turn-on the lawn mower <NUM> of the disclosure, it is required to press the turning-on button <NUM> first, and then pull the main knife switch pull rod <NUM>. Through performing the above two actions, it is possible to prevent an accidental turning-on due to an inadvertently touch of the turning-on button <NUM>, and thereby a safety factor of the lawn mower <NUM> is high.

The traveling wheel includes a pair of front traveling wheels <NUM> and a pair of rear traveling wheels <NUM>. The self-propelled motor includes a first self-propelled motor <NUM> and a second self-propelled motor <NUM>. The first self-propelled motor <NUM> is configured to drive the front traveling wheels <NUM> to self-propel. The second self-propelled motor <NUM> is configured to drive the rear traveling wheels <NUM> to self-propel. The first self-propelled motor <NUM> and the second self-propelled motor <NUM> are powered by the power supply assembly and electrically connected with the control circuit board <NUM> respectively. In the disclosure, the control circuit board <NUM> is a printed circuit board (PCB), and the first self-propelled motor <NUM> and the second self-propelled motor <NUM> are electrically connected to the PCB respectively, so that the turning-on and turning-off of the first self-propelled motor <NUM> and the second self-propelled motor <NUM> are controlled by the PCB.

It should be noted that the first self-propelled motor <NUM> is configured to drive the front traveling wheels <NUM> to self-propel, and the second self-propelled motor <NUM> is configured to drive the rear traveling wheels <NUM> to self-propel in the embodiment. Of course, the first self-propelled motor <NUM> can also be configured to drive the rear traveling wheels <NUM> to self-propel, and the second self-propelled motor <NUM> can be configured to drive the front traveling wheels <NUM> to self-propel, which is not limited herein.

The lawn mower <NUM> further includes a first speed reducing mechanism <NUM> connected with the first self-propelled motor <NUM> and a second speed reducing mechanism <NUM> connected with the second self-propelled motor <NUM>. Clutches (not shown) are arranged in each of the first speed reducing mechanism <NUM> and the second speed reducing mechanism <NUM>. The clutch of the first speed reducing mechanism <NUM> is configured to enable an output shaft of the first speed reducing mechanism <NUM> not to contact with a wheel shaft of each front traveling wheel <NUM> if the first self-propelled motor <NUM> is out of service, and the clutch of the second speed reducing mechanism <NUM> is configured to enable an output shaft of the second speed reducing mechanism <NUM> not to contact with a wheel shaft of each rear traveling wheel <NUM> if the second self-propelled motor <NUM> is out of service. Therefore, in a case that the first self-propelled motor <NUM> and/or the second self-propelled motor <NUM> are/is in a turned-off state, even if the lawn mower <NUM> is in moving state, the first self-propelled motor <NUM> and/or the second self-propelled motor <NUM> will not be reversely driven by the front traveling wheels <NUM> and/or the rear traveling wheels <NUM>. The clutch is common in a prior art, and a specific structure and a power principle thereof may be referred to a patent application No. <CIT>, it will not be described in detail herein.

In the disclosure, the first speed reducing mechanism <NUM> is arranged close to the first self-propelled motor <NUM>, each of the first speed reducing mechanism <NUM> and the first self-propelled motor <NUM> is arranged close to the front traveling wheels <NUM>. The second speed reducing mechanism <NUM> is arranged close to the second self-propelled motor <NUM>, each of the second speed reducing mechanism <NUM> and the second self-propelled motor <NUM> is arranged close to the rear traveling wheels <NUM>. With this arrangement, it is facilitated that the control circuit board <NUM> controls the turning-on or turning-off of the corresponding first self-propelled motor <NUM> and second self-propelled motor <NUM>, and then drives the front traveling wheels <NUM> to self-propelled using the first reducing mechanism <NUM> and the rear traveling wheels <NUM> to self-propelled using the second reducing mechanism <NUM>.

The lawn mower <NUM> further includes a first control element and a second control element. Specifically, the first control element is connected with the control circuit board <NUM> and configured to control the control circuit board <NUM> to turn-on or turn-off the first self-propelled motor <NUM>, and the second control element is configured to control the control circuit board <NUM> to turn-on or turn-off the second self-propelled motor <NUM>.

Specifically, the first control element is a self-propelled pull rod <NUM>, which is arranged close to the top of the push rod <NUM> and the third handle <NUM>. The first self-propelled motor <NUM> is turned-on, if the self-propelled pull rod <NUM> is pulled so as to fit the third handle <NUM>. The self-propelled pull rod <NUM> returns to an initial position thereof and the first self-propelled motor <NUM> is turned-off, if the self-propelled pull rod <NUM> is released. Of course, in order to increase a safety of the lawn mower, it is also expected that additional actions can be performed besides pulling the self-propelled pull rod <NUM> to realize the turning-on and turning-off of the first self-propelled motor <NUM>.

The main knife switch pull rod <NUM> is arranged on a side of the third handle <NUM>, and the self-propelled pull rod <NUM> is arranged on the other side of the third handle <NUM>. With this arrangement, when the lawn mower <NUM> is turned-on, the main knife switch pull rod <NUM> and the self-propelled pull rod <NUM> is simultaneously pulled to fit with the third handle <NUM>, thereby facilitating grasping of the main knife switch pull rod <NUM> and the self-propelled pull rod <NUM> by the operator.

There are several manners for the second control element to control the turning-on or turning-off of the second self-propelled motor <NUM>, and three of which will be described through three embodiments in detail in the following description, but it will not be limited herein.

Referring to <FIG>, a lawn mower <NUM> is shown according to the first embodiment of the disclosure. In the embodiment, the second control element is a push button <NUM> arranged close to the top of the push rod <NUM>, which is connected with the control circuit board <NUM>. When the push button <NUM> is pushed backward or forward, the control circuit board <NUM> is controlled to correspondingly turn-on or turn-off the second self-propelled motor <NUM>.

Specifically, the first handle <NUM> is provided with a self-propelled switch box <NUM>, and the push button <NUM> is disposed on the self-propelled switch box <NUM>. When the push button <NUM> is dialed by the operator forward (or backward), the control circuit board <NUM> controls the second self-propelled motor <NUM> to power on and thereby controls the turning-on of the second self-propelled motor <NUM>. When the push button <NUM> is pushed backward (or forward), the control circuit board <NUM> controls the second self-propelled motor <NUM> to turn-off and thereby controls the turning-off of the second self-propelled motor <NUM>.

In the embodiment, when the lawn mower <NUM> is traveling, the self-propelled pull rod <NUM> is pulled to enable the self-propelled pull rod <NUM> to fit with the third handle <NUM>, in this case, the first self-propelled motor <NUM> is turned-on to drive the front traveling wheels <NUM> to self-propel through the first speed reducing mechanism <NUM>, and the second self-propelled motor <NUM> is in a standby state. It should be noted that, in the embodiment, the premise that the second self-propelled motor <NUM> can be turned-on is that the first self-propelled motor <NUM> is in a turned-on state. That is to say, when the first self-propelled motor <NUM> is turned-off, the second self-propelled motor <NUM> will not be turned-on even if the push button <NUM> is in a turning-on state. Of course, in other embodiments, the operations of the first self-propelled motor <NUM> and the second self-propelled motor <NUM> may be independent of each other.

When the lawn mower <NUM> is traveling on a flat ground, the operation requirements can be met if the two front traveling wheels <NUM> are driven merely by the first self-propelled motor <NUM> to self-propel. In case of thick grasses and a large climbing resistance, the push button <NUM> is required to be pushed, so as to turn-on the second self-propelled motor <NUM> to thereby drive the rear traveling wheels <NUM> to self-propel through the second reducing mechanism <NUM>, thereby realizing four-wheel drive. Conversely, when a resistance on the flat ground is low or the lawn mower <NUM> is traveling downhill, the second self-propelled motor <NUM> may be turned-off by using the push button <NUM>, thereby effectively saving electric energy and prolonging the endurance of the lawn mower <NUM>. Further, if a self-propelled speed of the lawn mower <NUM> is still too high in this case, the operator may turn-off (i.e., release) the self-propelled pull rod <NUM> to turn off the first self-propelled motor <NUM> to further save electric energy.

Referring to <FIG>, a lawn mower <NUM>' is shown according to the second embodiment of the disclosure. In the embodiment, the second control element is a detection module (not shown), which is arranged on the control circuit board <NUM> and configured to detect a power of the first self-propelled motor <NUM>, comparing the power with a set value to determine whether the second self-propelled motor <NUM> needs to be turned-on or turned-off.

Specifically, since there is a small change in a power supply voltage of the first self-propelled motor <NUM>, the power of the first self-propelled motor <NUM> can be calculated by the detection module according to a current of the first self-propelled motor <NUM> detected by the detection module. Further, the detection module transmits the calculated power of the first self-propelled motor <NUM> to the control circuit board <NUM>, and then the control circuit board <NUM> controls the second self-propelled motor <NUM> to turn-on or turn-off according to the received power of the first self-propelled motor <NUM>. In the preferred embodiment, the control circuit board <NUM> controls the second self-propelled motor <NUM> to turn-on when the power of the first self-propelled motor <NUM> is higher than an upper limit of the set value, while the control circuit board <NUM> may control the second self-propelled motor <NUM> to turn-off when the power of the first self-propelled motor <NUM> is smaller than a lower limit of the set value. The upper limit of the set value may be in a range from <NUM> Watts (W) to <NUM> W, and preferably <NUM> W. The lower limit of the set value may be in a range from <NUM> W to <NUM> W, and preferably <NUM> W.

In the embodiment, when the lawn mower <NUM>' is traveling, the self-propelled pull rod <NUM> is pulled to enable the self-propelled pull rod <NUM> to fit with the third handle <NUM>, in this case, the first self-propelled motor <NUM> is turned-on to drive the front traveling wheels <NUM> to self-propel through the first speed reducing mechanism <NUM>, and the second self-propelled motor <NUM> is in a standby state.

When the lawn mower <NUM>' is traveling on a flat ground, the power of the first self-propelled motor <NUM> is small due to a small resistance, therefore, the operation requirements can be met if the two front traveling wheels <NUM> are driven merely by the first self-propelled motor <NUM> to self-propel.

In case of thick grasses and a large climbing resistance, a self-propelled load of the lawn mower <NUM>' is large. In this case, if the detection module detects that the power of the first self-propelled motor <NUM> is large and exceeds the upper limit of the set value, the second self-propelled motor <NUM> is turned-on to drive the rear traveling wheels <NUM> to self-propel through the second speed reducing mechanism <NUM>, thereby realizing four-wheel drive, in turn, reducing a running power of the first self-propelled motor <NUM> and avoiding overload of the first self-propelled motor <NUM>.

When the lawn mower <NUM>' is traveling downhill, the self-propelled load of the lawn mower <NUM>' is small due to a small resistance. In this case, if the detection module detects that the power of the first self-propelled motor <NUM> is small and smaller than the lower limit of the set value, the second self-propelled motor <NUM> is turned-off to enable the efficiency of the first self-propelled motor <NUM> in a better state. Further, if the self-propelled speed of the lawn mower <NUM>' is still too high in this case, the operator may turn-off (i.e., release) the self-propelled pull rod <NUM> to turn-off the first self-propelled motor <NUM>, thereby saving electric energy and prolonging the endurance of the lawn mower <NUM>'.

Referring to <FIG>, a lawn mower <NUM>" is shown according to the third embodiment of the disclosure. In the embodiment, the second control element is an angular velocity sensor <NUM>', which is arranged on the wheel shaft of each of the front traveling wheels <NUM> or the rear traveling wheels <NUM> and configured to transmit current angular velocity information of the corresponding traveling wheel to the control circuit board <NUM> in real time, and the control circuit board <NUM> determines whether the second self-propelled motor <NUM> needs to be turned-on or turned-off according to the received angular velocity information.

Specifically, since a size of the traveling wheels is fixed, the control circuit board <NUM> can calculate a current traveling speed of the lawn mower <NUM>" according to the angular velocity information of the traveling wheels, compare the current traveling speed with a set value. Specifically, if the current traveling speed of the lawn mower <NUM>" is smaller than a lower limit of a set value, the control circuit board <NUM> controls the second self-propelled motor <NUM> to turn-on; while if the current traveling speed of the lawn mower <NUM>" is higher than an upper limit of the set value, the control circuit board <NUM> controls the second self-propelled motor <NUM> to turn-off. The upper limit of the set value is in a range from <NUM> meters per second (m/s) to <NUM>/s, and preferably <NUM>/s; The lower limit of the set value is in a range from <NUM> to <NUM>/s, preferably <NUM>/s.

In the embodiment, when the lawn mower <NUM>" is traveling, the self-propelled pull rod <NUM> is pulled to enable the self-propelled pull rod <NUM> to fit with the third handle <NUM>, in this case, the first self-propelled motor <NUM> is turned-on to drive the front traveling wheels <NUM> to self-propel through the first speed reducing mechanism <NUM>, and the second self-propelled motor <NUM> is in a standby state.

When the lawn mower <NUM>" is traveling on a flat ground, a traveling speed of the lawn mower <NUM>" is between the upper limit and the lower limit of the set value, therefore, the operation requirements can be met if the two front traveling wheels <NUM> are driven merely by the first self-propelled motor <NUM> to self-propel.

In case of thick grasses and a large climbing resistance, the traveling speed of the lawn mower <NUM>" is reduced. In this case, if the control circuit board <NUM> calculates that the traveling speed of the lawn mower <NUM>" is reduced and smaller than the lower limit of the set value, the second self-propelled motor <NUM> is turned-on to drive the rear traveling wheels <NUM> to self-propel through the second deceleration mechanism <NUM>, thereby realizing four-wheel drive, and enabling the traveling speed of the lawn mower <NUM>" at a normal level.

When the lawn mower <NUM>" is traveling downhill, a self-propelled speed of the lawn mower <NUM>" is accelerated due to a small resistance. In this case, if the control circuit board <NUM> calculates that the traveling speed of the lawn mower <NUM>" is faster and higher than the upper limit of the set value, the second self-propelled motor <NUM> is turned-off to enable the traveling speed of the lawn mower <NUM>" at the normal level. Further, if the self-propelled speed of the lawn mower <NUM> "is still too high in this case, the operator may turn-off (i.e., release) the self-propelled pull rod <NUM> to turn-off the first self-propelled motor <NUM>, thereby saving electric energy and prolonging the endurance of the lawn mower <NUM>".

Combined with the above three embodiments, the following conclusions can be drawn. When the operation requirements can be met by driving a single self-propelled motor, only the first self-propelled motor <NUM> operates to realize the self-propelled of the two front traveling wheels <NUM>; while when the operation requirements cannot be met by driving a single self-propelled motor, the second self-propelled motor <NUM> further operates to realize four-wheel drive. The first self-propelled motor <NUM> and the second self-propelled motor <NUM> may be separately controlled, therefore, the effect of saving energy is not only achieved, but it is also convenient for operation and maintenance.

The enclosure may snap-fit with the housing <NUM>, and is configured to cover the housing <NUM>, the power assembly <NUM>, the first self-propelled motor <NUM>, the second self-propelled motor <NUM>, the control circuit board <NUM> and the like, so as to prevent the power assembly, the power assembly <NUM>, the first self-propelled motor <NUM>, the second self-propelled motor <NUM> and the control circuit board <NUM> from being damaged by dust, water stains, etc., and to ensure that the lawn mowers <NUM>, <NUM>' and <NUM>" can operate safely and stably, thereby prolonging the service life of the lawn mowers <NUM>, <NUM>' and <NUM>".

In summary, for the lawn mowers <NUM>, <NUM>', and <NUM>" of the disclosure, the first control element is set to control the turning-on or turning-off of the first self-propelled motor <NUM>, and the second control element is set to control the turning-on or turning-off of the second self-propelled motor <NUM>, such that when the operation requirements can be met by driving a single self-propelled motor, only the first self-propelled motor <NUM> is controlled to operate so as to realize two-wheel drive; while when the operation requirements cannot be met by driving a single self-propelled motor, the second self-propelled motor <NUM> may be further controlled to operate to realize four-wheel drive. Moreover, the first self-propelled motor <NUM> and the second self-propelled motor <NUM> may be separately controlled, therefore, the effect of saving energy is not only achieved, but it is also convenient for operation and maintenance.

Claim 1:
A lawn mower (<NUM>), comprising:
a housing (<NUM>);
a push rod (<NUM>) connected with the housing (<NUM>);
a traveling wheel for supporting the lawn mower (<NUM>);
a self-propelled motor for driving the traveling wheel to self-propel; and
a control circuit board (<NUM>) for controlling turning-on and turning-off of the self-propelled motor;
wherein the traveling wheel comprises a pair of front traveling wheels (<NUM>) and a pair of rear traveling wheels (<NUM>),
characterized in that,
the self-propelled motor comprises a first self-propelled motor (<NUM>) configured to drive the front traveling wheels (<NUM>) to self-propel and a second self-propelled motor (<NUM>) configured to drive the rear traveling wheels (<NUM>) to self-propel, the lawn mower (<NUM>) further comprises a first control element and a second control element, the first control element is configured to control the control circuit board (<NUM>) to turn-on or turn-off the first self-propelled motor (<NUM>), and the second control element is configured to control the control circuit board (<NUM>) to turn-on or turn-off the second self-propelled motor (<NUM>).