Patent Description:
A working device such as a bucket of an excavator or a traveling device is driven by an working fluid delivered from a hydraulic pump. Such a hydraulic pump is driven by an internal combustion engine. However, an excavator driven by an engine emits not only exhausts but also loud noise, so it is not suitable for work at construction sites such as hospitals or schools that are sensitive to smoke or noise. For this reason, an electric excavator which drives a hydraulic pump using an electric motor connected to a battery has recently been developed.

Engine-driven excavators use engine cooling water to heat the driver's seat. More specifically, in the case of an engine-driven excavator, cooling water for cooling the engine cools the engine while flowing along a flow path formed in the engine by a water pump, and the cooling water heated by the engine is circulated to a radiator to be cooled. Part of the cooling water heated by the engine is diverted to a heat exchanger and used as a heat source for heating the driver's seat.

However, in the case of an electric excavator, since there is no engine, a method of heating a driver's seat using engine cooling water may not be used.

<CIT> provides a process for exploiting the waste heat from hydraulic drive machines mounted on vehicles in a working fluid circuit composed at least of a pump group, a collector group and a cooling group.

The present invention is directed to a heater system for an electric construction machine capable of heating a cabin.

According to the present invention, a heater system of an electric construction machine including a hydraulic pump driven by an electric motor and a main control valve configured to supply a working fluid discharged from the hydraulic pump to at least one actuator is provided, as defined by independent claim <NUM>. The heater system includes: a heater core which is disposed downstream of the actuator and through which the working fluid passes, wherein a heated air is supplied to a cabin through the heater core using a heat of the working fluid.

According to the present invention, the heater system of an electric construction machine further includes: a switching valve configured to selectively supply the working fluid to the heater core.

According to the present invention, the heater system of an electric construction machine further includes: an oil cooler configured to control a temperature of the working fluid.

Preferably, the heater system of an electric construction machine may further include: an oil cooler disposed upstream of the heater core and configured to control a temperature of the working fluid.

Preferably, the oil cooler may be disposed between the switching valve and a working fluid tank or between the switching valve and the main control valve.

According to the present invention, a flow path of the working fluid supplied through the switching valve is branched into each of the heater core, the oil cooler and a working fluid tank.

Preferably, when the temperature of the working fluid supplied from the main control valve is equal to or less than a preset first temperature, the switching valve may be switched so that the working fluid is supplied to the working fluid tank.

Preferably, when the temperature of the working fluid supplied from the main control valve is higher than a preset first temperature, the switching valve may be switched so that the working fluid is supplied to the heater core or the working fluid tank.

Preferably, when the temperature of the working fluid supplied from the main control valve is equal to or higher than a preset second temperature, the switching valve may be switched so that the working fluid is supplied to the heater core, the oil cooler or the working fluid tank.

Preferably, the heater system of an electric construction machine may further include: a fan member configured to control the temperature of the working fluid passing through the oil cooler through control of a rotational speed.

Preferably, the heater system of an electric construction machine may further include: an auxiliary heating device configured to supply the heated air to the cabin.

Preferably, the switching valve may be configured to supply the working fluid to the heater core according to a worker's ON signal.

Preferably, operation of the fan member may be stopped when the temperature of the working fluid is equal to or less than a preset temperature.

Preferably, the fan member may be operated only when the temperature of the working fluid is equal to or higher than a preset temperature.

As such, a heater system for an electric construction machine according to various embodiments of the present invention may be applied without a significant change to the conventional hydraulic system or air conditioning system, thereby reducing cost or time in the manufacturing process.

In addition, by using a working fluid of the conventional hydraulic system in the electric construction machine as a heat source, it is not necessary to install a separate heating device, thereby providing the effect of reducing manufacturing costs.

In addition, even when an auxiliary heating device is operated, since it is limitedly operated according to the temperature of the working fluid, the use time thereof may be reduced, thereby reducing the electric energy of the battery.

Hereinafter, for convenience of description, some embodiments of the present invention will be described through exemplary drawings. In describing the reference numerals for the components of each drawing, the same numerals indicate the same components as much as possible, even if they are illustrated in different drawings.

Terms or words used in this specification and claims should not be limited to their usual or dictionary meanings, and it should be interpreted as a meaning and concept consistent with the present invention based on the principle that the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. Also, terms such as first, second, A, B, (a), and (b) may be used to describe components of an embodiment of the present invention. These terms are only used to distinguish the component from other components, and the nature, order, or sequence of the corresponding component is not limited by the term. When an element is described as being 'connected' or 'coupled' to another element, that element may be directly connected or coupled to the other element, but it should be understood that there is another element 'connected' or 'coupled' between the element and the other element.

Hereinafter, a heater system of an electric construction machine according to various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<FIG> is a view conceptually illustrating a supply path of a working fluid (e.g., hydraulic oil) when a heater system of an electric construction machine according to an embodiment is in an OFF state, <FIG> is a view conceptually illustrating a supply path of a working fluid when a heater system of an electric construction machine according to an embodiment is in an ON state, <FIG> is a view conceptually illustrating a supply path of a working fluid when a heater system of an electric construction machine is in an OFF state in an embodiment of the present invention, <FIG> is a view conceptually illustrating a supply path of a working fluid when a heater system of an electric construction machine is in an ON state in another embodiment of the present invention, <FIG> is a view conceptually illustrating a supply path of a working fluid when a temperature of a working fluid in a heater system of an electric construction machine according to an exemplary embodiment of the present invention is equal to or less than a preset first temperature, <FIG> is a view conceptually illustrating a supply path of a working fluid when a temperature of a working fluid is higher than a preset first temperature in a heater system of an electric construction machine according to an exemplary embodiment of the present invention, <FIG> is a view conceptually illustrating a supply path of a working fluid when a temperature of a working fluid is higher than a preset second temperature in a heater system of an electric construction machine according to an exemplary embodiment of the present invention, and <FIG> is a graph illustrating a rotational speed control state of a fan member <NUM> according to a temperature of a working fluid flowing into an oil cooler <NUM> in a heater system of an electric construction machine according to various embodiments of the present invention.

Referring to <FIG>, a heater system of an electric construction machine according to various embodiments of the present invention relates to a heater system applied to an electric construction machine driven by an electric motor <NUM>.

As illustrated in <FIG>, an electric construction machine to which a heater system is applied replaces an internal combustion engine such as an engine and has a structure in which a hydraulic pump <NUM> is driven through an electric motor <NUM> using a battery <NUM>. When the hydraulic pump <NUM> is driven by the electric motor <NUM>, a working fluid for operating an actuator <NUM> such as a work apparatus is discharged from the pump. The working fluid discharged from the pump may be supplied to the actuator <NUM> for operating a cylinder <NUM> such as a boom, arm, bucket, and the like, a travel motor <NUM>, or a swing motor <NUM> through a main control valve (MCV) <NUM>.

A temperature of the working fluid increases in the process of operating the actuator <NUM>, and the present invention proposes a method of using the heat of the working fluid used when operating the construction machine as a heat source.

The heater system of the electric construction machine according to various embodiments of the present invention may include a heater core <NUM>, a switching valve <NUM>, and an oil cooler <NUM>. In addition, a fan member <NUM> of the oil cooler <NUM> and an auxiliary heating device <NUM> may be further included.

In the present invention, a control switch capable of controlling on/off of the heater system may be disposed inside a cabin <NUM>, and operation of the heater system may be determined by an worker manipulating the control switch. When an worker operates the control switch in an ON state, the working fluid whose temperature has increased may be supplied to the heater core <NUM>.

The heater core may be disposed downstream of the main control valve <NUM> and may form a flow path through which the working fluid may flow therein. The heater core <NUM> may be formed in various structures, and is not limited to its shape.

In the process of operating the actuator <NUM>, a working fluid whose temperature has increased may flow into the heater core <NUM>. When the working fluid is introduced into the heater core <NUM>, the temperature of the heater core <NUM> rises due to the temperature of the working fluid, and a waste heat of the working fluid may be recovered by using the heater core <NUM>.

That is, the heat of the working fluid may be recovered by passing the working fluid through the heater core <NUM> so that the heated air may be supplied to the inside of the cabin <NUM>. To this end, a heater fan <NUM> for generating a flow of air toward the inside of the cabin <NUM> may be disposed on one side of the heater core <NUM>.

The working fluid whose heat is recovered through the heater core <NUM> may be supplied to the pump again through the working fluid tank <NUM> in a state in which the temperature is lowered again.

A switching valve <NUM> may be disposed upstream of the heater core <NUM>. The switching valve <NUM> may be switched by an operation signal of the control switch. A supply line of the working fluid passing through the actuator <NUM> may be controlled through the switching valve <NUM>. As the switching valve <NUM> is switched according to whether the control switch of the heater system is operated by the worker, the working fluid passing through the actuator <NUM> may be selectively supplied to the working fluid tank <NUM> or the heater core <NUM>.

In one embodiment, when a worker turns on the heater system, the switching valve <NUM> may be switched to supply the working fluid to the heater core <NUM> according to a corresponding signal. Also, when the worker turns off the heater system, the switching valve <NUM> may be switched so that the working fluid does not flow into the heater core <NUM> and is returned to the working fluid tank <NUM>.

In one embodiment, the switching valve <NUM> and the heater core <NUM> may be disposed downstream of the oil cooler <NUM>. In this case, the temperature of the working fluid flowing into the heater core <NUM> through the switching valve <NUM> may be properly adjusted by the oil cooler <NUM>.

In another embodiment, the switching valve <NUM> and the heater core <NUM> may be disposed upstream of the oil cooler <NUM>. In this case, the working fluid may be recovered to the working fluid tank <NUM> in a cooled state by the oil cooler <NUM>.

The heater system of the electric construction machine of the present invention may include the oil cooler <NUM>. The oil cooler <NUM> may be disposed on the working fluid flow path to control the temperature of the working fluid whose temperature has increased while passing through the actuator <NUM>. At least one temperature sensor capable of sensing the temperature of the working fluid may be disposed in the oil cooler <NUM>. When the working fluid flows into the oil cooler <NUM>, the fan member <NUM> installed on one side of the oil cooler <NUM> is operated to cool the working fluid inside the oil cooler <NUM>. In the present invention, the temperature of the working fluid may be controlled by controlling a rotational speed of the fan member <NUM>.

In one embodiment, the oil cooler <NUM> is disposed upstream of the switching valve <NUM> and the heater core <NUM> to adjust the temperature of working fluid flowing into the heater core <NUM>.

Referring to <FIG>, the working fluid whose temperature has risen in the process of passing through the actuator <NUM> may be supplied to the heater core <NUM> or the working fluid tank <NUM> while the temperature is constantly controlled through the oil cooler <NUM>. When the control switch of the heater system is in the OFF state, the working fluid may be returned to the working fluid tank <NUM> through the switching valve <NUM> and supplied to the hydraulic pump <NUM> again, and in one embodiment, the oil cooler <NUM> may control the working fluid temperature to a preset temperature. For example, the preset maximum temperature may be <NUM> degrees as illustrated in (a) of <FIG>, and in such a case, the fan member <NUM> of the oil cooler <NUM> may operate from approximately <NUM> degrees to control the temperature of the working oil to <NUM> degrees while constantly increasing the rotational speed.

Referring to <FIG>, when the control switch of the heater system is in an ON state, the working fluid may be supplied to the heater core <NUM> through the switching valve <NUM>. In one embodiment, the oil cooler <NUM> may control the temperature of the working fluid flowing into the heater core <NUM> to reach a preset maximum temperature. In addition, the oil cooler <NUM> may operate the fan member <NUM> only when the temperature of the working fluid is equal to or higher than a preset minimum temperature and may stop the operation of the fan member <NUM> when the working fluid temperature is lower than the preset minimum temperature. This is because air sufficiently heated through the heater core <NUM> may not be provided to the cabin <NUM> when the temperature of the working fluid is less than the preset minimum temperature. However, in this case, hot air may be supplied to the cabin <NUM> through an auxiliary heating device <NUM> such as a positive temperature coefficient (PTC) heater or a heat pump. Thereafter, when the temperature of the working fluid rises to or above the preset minimum temperature, the operation of the auxiliary heating device <NUM> is stopped, and the heated air may be supplied to the cabin <NUM> by using the heat of the working fluid recovered through the heater core <NUM>.

In one embodiment, the preset maximum temperature may be <NUM> degrees as in the case where the control switch is in an OFF state, but embodiments are not limited thereto, and the appropriate temperature may be changed according to the intensity (temperature) of the heater requested by the driver.

In one embodiment, when the control switch is in an ON state, an operating start temperature of the fan member <NUM> may be set higher than the case when the control switch is in an OFF state. For example, the operating start temperature of the fan member <NUM> when the control switch is in an ON state may be set to a second temperature, for example, may be exemplarily set to <NUM> degrees as illustrated in (b) of <FIG>, which is higher than a first temperature that is the operating start temperature of the fan member <NUM> when the control switch is in an OFF state. In this case, the fan member <NUM> may operate at a temperature of about <NUM> degrees and control the temperature of the working fluid to be <NUM> degrees while constantly increasing the rotational speed.

In the present invention, as described above, the heated air may be generated through the heater core <NUM> using the heat of the working fluid, but since it is difficult to supply the heated air to the cabin <NUM> in a state where the temperature of the working fluid has not sufficiently risen after starting the construction machine, the auxiliary heating device <NUM> may be further provided. In one embodiment, the auxiliary heating device <NUM> may include a PTC heater or a heat pump, but embodiments are not limited thereto, and it is obvious that any known heating device other than a heating device using waste heat of a working fluid may be used.

In one embodiment, when the control switch of the heater system is operated to an ON state, the switching valve <NUM> is switched and the working fluid passing through the oil cooler <NUM> may flow into the heater core <NUM>. When the temperature of the working fluid introduced into the oil cooler <NUM> is lower than the preset second temperature, the operation of the fan member <NUM> of the oil cooler <NUM> may be stopped. In such a case, since the heater core <NUM> alone may not provide sufficiently heated air, the heated air may be supplied to the cabin <NUM> through the auxiliary heating device <NUM>. Then, when the temperature of the working fluid flowing into the oil cooler <NUM> becomes equal to or higher than the preset second temperature, the operation of the auxiliary heating device <NUM> is stopped and the heated air may be provided through the heater core <NUM>. In addition, when the temperature of the working fluid becomes equal to or higher than the preset second temperature, the operation of the fan member <NUM> of the oil cooler <NUM> starts, and the maximum temperature of the working fluid may be controlled to be <NUM> degrees while constantly increasing the rotational speed as illustrated in (b) of <FIG>.

However, although it has been described here that the oil cooler <NUM> is disposed upstream of the switching valve <NUM> and the heater core <NUM>, the oil cooler <NUM> may be disposed downstream of the switching valve <NUM> or the heater core <NUM> as illustrated in <FIG> and <FIG>. Referring to <FIG> and <FIG>, the oil cooler <NUM> may be disposed downstream of the switching valve <NUM>, that is, between the switching valve <NUM> and the working fluid tank <NUM>. In this case, the fan member <NUM> of the oil cooler <NUM> may be controlled as in the case where the control switch of the heater system is off. Referring to <FIG>, when the driver turns off the control switch of the heater system, the temperature of the hot working fluid may be lowered while passing through the oil cooler <NUM> via the switching valve <NUM> and the working fluid may return to the working fluid tank <NUM>. Referring to <FIG>, when the driver turns on the control switch of the heater system, the switching valve <NUM> is switched and the hot working fluid is introduced into the heater core <NUM> without passing through the oil cooler <NUM>, and heating of the cabin may be performed by the heat of hydraulic oil.

In an exemplary embodiment of the present invention, unlike the embodiments of <FIG> described above, the switching valve <NUM> may be a four-way switching valve. Referring to <FIG>, in an exemplary embodiment of the present invention, the flow path of the working fluid supplied through the switching valve <NUM> may be configured to branch to each of the heater core <NUM>, the oil cooler <NUM> and the working fluid tank <NUM>.

First, referring to <FIG>, when the temperature of the working fluid supplied from the main control valve <NUM> is equal to or less than the preset first temperature, the switching valve <NUM> may be switched so that the working fluid is supplied to the working fluid tank <NUM>. Due to switching of the switching valve <NUM>, the flow path communicating from the switching valve <NUM> to the heater core <NUM> and the oil cooler <NUM> may be closed, such that the working fluid may be directly recovered to the working fluid tank <NUM> without passing through the heater core <NUM> or the oil cooler <NUM>. In this case, the preset first temperature may be a temperature low enough to make it difficult to use the heater core <NUM>, and may be set to, for example, <NUM> degrees, but embodiments are not limited thereto. That is, in <FIG>, since the working fluid that is not sufficiently hot may circulate quickly along the hydraulic system of the construction machine through the hydraulic pump <NUM>, the temperature may rise quickly.

Referring to <FIG>, when the temperature of the working fluid supplied from the main control valve <NUM> is higher than the preset first temperature, the switching valve <NUM> maybe switched such that the working fluid may be supplied to the heater core <NUM> or the working fluid tank <NUM>. In this case, the preset first temperature may be a temperature low enough to make it difficult to use the heater core <NUM>, and may be set to, for example, <NUM> degrees, but embodiments are not limited thereto. In this case, since the temperature of the working fluid is appropriately high enough to be used in the heater core, the working fluid may be supplied to the heater core <NUM> according to the control switch operation of the heater system by the worker and may be used as a heat source of the heater. In this case, since the temperature of the working fluid is not hot enough to require cooling, the flow path communicating from the switching valve <NUM> to the oil cooler <NUM> may be closed.

Referring to <FIG>, when the temperature of the working fluid supplied from the main control valve <NUM> is equal to or higher than the preset second temperature, the switching valve <NUM> may be switched such that the working fluid may be supplied to any one of the heater core <NUM>, the oil cooler <NUM>, and the working fluid tank <NUM>. In such a case, the preset second temperature may be a temperature at which the temperature of the working fluid becomes hot enough to require cooling using the oil cooler <NUM> according to the operation of the construction machine, and may be set to, for example, <NUM> degrees, but embodiments are not limited thereto. Here, since the temperature of the working fluid is sufficiently hot, the hot working fluid that has passed through the switching valve <NUM> may be supplied to the heater core <NUM> according to the control switch operation of the heater system by the worker and may be used as a heat source for the heater or may be supplied to the oil cooler <NUM> for cooling. Here, control of the rotational speed of the fan member <NUM> of the oil cooler <NUM> is the same as in the above-described embodiment. In addition, the working fluid may be directly recovered to the working fluid tank <NUM> without being supplied to the heater core <NUM> or the oil cooler <NUM>.

The working fluid whose heat has been recovered through the heater core <NUM> or the working fluid whose temperature is controlled to maintain the proper maximum temperature by the oil cooler <NUM> may be continuously circulated by being supplied again to the hydraulic pump <NUM> via the working fluid tank <NUM>.

The heater system proposed in the present invention may be applied to an air mixed type air conditioner, and in this case, the temperature of the air supplied to the cabin <NUM> may be adjusted by mixing the heated air generated by recovering heat from the working fluid through the heater core <NUM> and the cooled air generated from an air conditioner. In addition, when the heater system of the present invention is applied to a water valve type air conditioner, the temperature of the air supplied to the cabin <NUM> may be adjusted by controlling a flow rate of the working fluid flowing into the heater core <NUM>.

As such, the heater system of the electric construction machine according to various embodiments of the present invention may be applied to the conventional hydraulic system or air conditioning system without a significant change, thereby reducing cost or time in the manufacturing process. In addition, by using the working fluid of the conventional hydraulic system in the electric construction machine as a heat source, there is no need to install a separate heating device, which has the effect of reducing manufacturing costs. In addition, even when the auxiliary heating device <NUM> is operated, since it is limitedly operated according to the temperature of the working fluid, the use time thereof may be reduced, thereby reducing the electrical energy of the battery <NUM>.

Claim 1:
A heater system of an electric construction machine comprising a hydraulic pump (<NUM>) driven by an electric motor (<NUM>) and a main control valve (<NUM>) configured to supply a working fluid discharged from the hydraulic pump (<NUM>) to at least one actuator, the heater system comprising:
a heater core (<NUM>) which is disposed downstream of the actuator and through which the working fluid passes,
a switching valve (<NUM>) configured to selectively supply the working fluid to the heater core (<NUM>); and
an oil cooler (<NUM>) configured to control a temperature of the working fluid,
wherein a heated air is supplied to a cabin through the heater core using a heat of the working fluid, characterized in that
a flow path of the working fluid supplied through the switching valve (<NUM>) is branched into each of the heater core (<NUM>), the oil cooler (<NUM>) and a working fluid tank (<NUM>).