Patent Application
20130195697
This application claims priority from Korean Patent
Application No. 10-2012-0009019, filed on Jan. 30, 2012 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field
Apparatuses and methods consistent with the exemplary embodiments relate to a hydraulic power steering pump having a wet type motor with an open type magnet, and more particularly to a hydraulic power steering pump having a wet type motor with an open type magnet, in which the wet type motor is improved in a structure of a rotor.
2. Description of the Related Art
A vehicle is a modern representative transport unit into which a lot of parts are assembled. In such a vehicle, a steering wheel is typically turned so that a driver can control a vehicle's going direction. Thus, a wheel connected to the steering wheel is turned and therefore a driver steers the vehicle. Among many parts of the vehicle, a steering device allows a driver to steer the vehicle in a direction as s/he desires.
The steering device includes a hydraulic power steering device with a pump for supplying hydraulic pressure to assist force given by a driver to turn the steering wheel given by a driver so that the driver can easily turn the steering wheel.
The hydraulic power steering device (hereinafter, referred to as a ‘steering device’) uses a power steering gear to distribute the hydraulic pressure supplied from the hydraulic power steering pump installed in the middle of a steering linkage connected to the steering wheel, and uses an output shaft to apply the distributed hydraulic pressure to a steerage wheel (a front wheel or a rear wheel), so that a driver can slightly and quickly steer the vehicle with small force. That is, the steering device serves to reduce force needed for a driver to control the steering wheel, and prevent a shock from being transferred from a road surface to the steering wheel via the front wheel.
The steering device is typically configured with an input transfer device that generates steering torque and transferring the steering torque or changing the direction of the steering torque, a distribution device that generates steering assistant force or decreases the steering assistant force, and an output device that properly converts input torque and displacement or changes the direction of the steering torque. Here, the input transfer device includes steering linkage such as a steering wheel, a drag link, a middle shaft, etc., the distribution device includes a hydraulic power steering pump, a control valve, etc., and the output device includes a steering gear having a power cylinder or the like, a tie rod, an end, etc.
Meanwhile, the hydraulic power steering pump is generally classified into two according to driving methods. One is to receive motive power from an engine, and the other is to drive the hydraulic power steering pump by a separate electric motor without receiving the motive power from the engine. Recently, an electric-driving hydraulic power steering pump for operating the hydraulic power steering pump has been preferred only when it is needed to pursue more efficient and environmentally-friendly vehicle.
A hydraulic power steering pump system including the electric-driving hydraulic power steering pump has a little different structure from a conventional engine-driving hydraulic power steering pump. The hydraulic power steering pump includes an electric motor for providing power, a pump assembly for pressurizing a fluid by rotation of an electric motor, a housing for supporting the electric motor and the pump assembly and storing and guiding the fluid, and a controller for controlling the electric motor based on an angle of the steering wheel or the like, pressure of the hydraulic power steering pump, etc.
The hydraulic power steering pump sucks oil through a sucking hose as the engine or electric motor is driven to rotate the pumping gear, and discharges the pressurized oil. Also, a steering pump is generally coupled with a flux control valve for controlling the amount of oil discharged. That is, a discharging amount per unit time is increased or decreased in proportion to a rotation number of the engine since the steering pump has a constant discharging amount per its rotation. Further, the hydraulic power steering pump is provided with a relief valve capable of adjusting the maximum level of fluid pressure not to be higher than necessary.
Recently, more and more hydraulic power steering pumps driven by the electric motor have been developed in light of fuel efficiency improvement and environmentally-friendly trend. Further, a wet type motor through which operating fluid passes is more preferable in consideration of cooling or the like.
As a related art, there is an example of Korean Patent Publication No. 2006-5340 (2006 Jan. 17).
A driving motor 12 of the related art shown in
One or more exemplary embodiments may provide an aspect of the present invention is to provide a hydraulic power steering pump having a wet type motor with an open type magnet, in which a coupling structure of a permanent magnet arranged in the rotor is improved to enhance magnetic properties of the permanent magnet and thus enhance the efficiency of the motor.
Another exemplary embodiment provides a hydraulic power steering pump having a wet type motor with an open type magnet, in which a coupling structure of a permanent magnet is simplified to reduce costs of molding or the like and thus improve economical efficiency.
Still another exemplary embodiment provides a hydraulic power steering pump having a wet type motor with an open type magnet, which has a simple structure to simplify processes for manufacture, assembly, etc.
According to an aspect of another exemplary embodiment, a hydraulic power steering pump including a wet type motor with an open type magnet is provided including: a housing; a gear pump module supported at one side of the housing and pressurizing a fluid; and a motor module supported at the other side of the housing and providing driving force to the gear pump module, the motor module including a stator that is supported by the housing and receives electric current based on supplied power, and a rotor that includes a motor rotation shaft rotated by the stator and a permanent magnet generating magnetic force, and an outer side of the permanent magnet being supported by the motor rotation shaft to have an exposed portion exposed toward the stator.
The rotor may be arranged within flow of a fluid.
The rotor may include a yoke holder coupled to the motor rotation shaft, a yoke supported by the yoke holder, and the permanent magnets plurally arranged outside the yoke, and the yoke holder includes a permanent magnet holder to support one end of each permanent magnet along a lengthwise direction of the motor rotation shaft.
The yoke holder may include ribs that divide the yoke holder in a circumferential direction to separate the permanent magnets from each other if the permanent magnets are arranged in the circumferential direction of the yoke holder.
The hydraulic power steering pump may further include a separation preventing cab member including a skirt surrounding the other end of the permanent magnet along the lengthwise direction of the motor rotation shaft so that each permanent magnet coupled to the yoke can be prevented from separation in the circumferential direction.
The above and/or other aspects will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings, in which:
Hereinafter, exemplary embodiments of a hydraulic power steering pump having a wet type motor with an open type magnet will be described with reference to
According to an exemplary embodiment, a hydraulic power steering pump 100, which generates hydraulic pressure for assisting torque of a steer wheel for a vehicle, is a gear type pump among various types of pump. As shown in
For reference, upward and downward directions in
The housing 110 forms most of an outer appearance of the hydraulic power steering pump 100, and is hard enough to support and accommodate various elements. The housing 110 may be made of steel materials, or may be cast with aluminum alloy to be lightweight.
The housing 110 includes the partition wall member 117 for partitioning an inner space thereof into upper and lower spaces. A gear pump module accommodating unit 113 is formed above the partition wall member 117 and accommodates the gear pump module 130, and a motor module accommodating unit 115 is formed below the partition wall member 117 and accommodates the motor module 150.
Also, the partition wall member 117 is formed with a discharging hole 119 at one side thereof, through which the pressurized working fluid for giving assisting force to the steering wheel is discharged from the hydraulic power steering pump 100. Alternatively, the discharging hole 119 may be formed at a necessary position of the housing 110.
Further, the partition wall member 117 is formed with a shaft hole 117a penetrating the center thereof so that torque of the motor module 150 can be transmitted to the gear pump module 130, a central sucking channel 117c formed so that the working fluid can flow from the second sucking fluid shock absorber 195b to the gear pump module 130, and a vertical sucking channel 117b formed to guide the fluid introduced from the sucking hole 193 to flow from the first sucking fluid shock absorber 195a to the second sucking fluid shock absorber 195b.
The motor module 150 includes a wet type motor accommodated in a second sucking fluid shock absorber 195b and being in contact with the working fluid.
Further, the hydraulic power steering pump 100 may include a driving circuit module 170 that applies electric power to the motor module 150, controls the motor module 150 to be driven, transmits and receives various signals to and from an engine control means (not shown), and transmits and receives signals from and to a sensor. The driving circuit module 170 includes a driving circuit member 175 having a printed circuit board (PCB) or the like for communication and control of various signals, and a driving circuit module supporting member 173 supporting the driving circuit member 175 and coupled to the housing 110 so that the driving circuit member 175 can be isolated from the working fluid.
Further, the reference numeral of ‘177’ indicates a wiring entrance via which an electric wire, a cable, etc. connected to the driving circuit module 170 or the motor module 150 can enter or exit.
The gear pump module 130 includes the gear pump housing 110, a gear pump cover 133 sealing up the gear pump housing 110, and a pumping unit 135 provided in the gear pump housing 110 and pressurizing the sucked working fluid toward the engaged pumping gear 135a. The gear pump module 130 includes a pump module holding member 139a having a bolt for coupling the gear pump module 130 with the partition wall member 117, and a relief valve 138 discharging a high pressurized working fluid pressurized by the pumping unit 135 toward a low pressure portion if discharging pressurized working fluid pressure reaches some degree. Here, the high pressure working fluid of the pressurized shock absorber 132, discharged from the relief valve 138, may be discharged to a first sucking fluid shock absorber 195a where a low pressure working fluid is stored.
The gear pump housing 110 includes the pumping unit 135 accommodated in a pumping-unit accommodating portion 136 to pressure a low-pressure working fluid up to a high-pressure working fluid.
The pumping unit 135 includes the pumping gears 135a engaged to each other to pressurize the low-pressure working fluid into the high-pressure working fluid, the gear housing 110 supporting the pair of pumping gears 135a at opposite ends, and a relatively long gear pump rotation shaft 137 and a relatively short gear pump rotation short shaft 137b which are coupled to a motor rotation shaft 151 and allow the pumping gears 135a to turn.
The pressurized shock absorber 132 is a space formed in a vertically lengthwise direction along a partial circumferential direction of the gear pump internal housing 131d. The cross-section of the pressurized shock absorber 132 is narrowing along a flowing direction of the working fluid from a discharging area of the pumping unit 135 to the discharging direction of the gear pump module 130.
Although it is not shown, the pressurized shock absorber 132 may for example have a ‘U’-shaped cross-section in the discharging area of the pumping unit 135, and be approximate to a circle as the ‘U’-shaped cross-section is tapering along the flowing direction of the working fluid discharged from the gear pump module 130.
Thus, the cross-section becomes wider in such a narrow channel, i.e., a shock absorber sucking hole (not shown), and becomes narrower again in direction toward a narrow channel, i.e., a shock absorber discharging hole (not shown), thereby forming the pressurized shock absorber 132 so that the pulsation of the pressurized and discharged working fluid can be effectively reduced via the pressurized shock absorber 132.
The sucking fluid shock absorber 195a, 195b includes a first sucking fluid shock absorber 195a provided as a space among the partition wall member 117, the cap 190 and the gear pump module 130, and a second sucking fluid shock absorber 195b provided as a space among the partition wall member 117, the housing cover 180 and the motor module 150. That is, the maximum space as possible may be formed so that the pulsation generated in the working fluid as the working fluid sucked and pressurized by the pumping gear 135a flows can be absorbed in the working fluid itself.
The cap 190 is coupled to a top of the housing 110 so as to prevent the working fluid filled in the first sucking fluid shock absorber 195a from leaking. The cap 190 is formed with the sucking hole 193 at one side thereof to guide the working fluid introduced from a tank (not shown) storing the working fluid to the hydraulic power steering pump 100. Alternatively, the sucking hole 193 may be formed in the housing 110 as necessary. The cap 190 may be molded with a material such as a plastic compound to reduce weight.
With this configuration, an effect on reducing the pulsation due to the channel of the hydraulic power steering pump 100 according to an exemplary embodiment will be schematically described.
First, the hydraulic power steering pump 100 of a gear type repetitively increases and decreases the discharging amount due to characteristics of the pumping gear 135a, and the increase/decrease of the discharging amount causes the pulsation of the hydraulic power steering pump 100. Meanwhile, the pulsation of the discharging side causes the pulsation of the sucking side. To prevent the pulsation of the sucking or discharging side, a large space is provided in the channel for sucking or discharging the working fluid so that the working fluid stored in the large space can reduce the pulsation. Further, the channels narrower than such a large space are formed in front and back of the storage space and thus prevent the pulsation from being transferred to another channel.
That is, the working fluid in the narrow sucking hole 193 is guided toward a large storage space, i.e., toward the first sucking fluid shock absorber 195a while being sucked in the pumping unit 135, and guided by a plurality of narrow vertical sucking channels 117b formed in the partition wall member 117 toward a large space, i.e., toward the second sucking fluid shock absorber 195b.
Further, the fluid stored in the second sucking fluid shock absorber 195b is pressurized in the pumping unit 135 via the central sucking channel 117c penetrating the center region of the partition wall member 117, guided to the relatively large space, i.e., to the pressurized shock absorber 132 via a relatively narrow shock absorber sucking hole (not shown), and guided to the discharging hole 119 of the hydraulic power steering pump 100 via the narrow discharging hole 119, the cross-section of which gets narrower, thereby acting as the pressurized working fluid. That is, the volume of the channel for the working fluid is enlarged so that the expanded working fluid can prevent the pulsation at the discharging to sucking sides.
Thus, the pulsation of the working fluid sucked into or discharged from the pumping unit 135 can be effectively reduced through the sucking fluid shock absorber 195a, 195b and the pressurized shock absorber 132. Also, the sucking fluid shock absorber 195a, 195b may fully use a space formed by the pump housing, the cap 190 and the housing cover 180, and the pressurized shock absorber 132 is formed in the pump housing 110 so that the hydraulic power steering pump 100 can be formed more compactly.
The motor module 150 is coupled to and supported by the motor module accommodating unit 115 of the housing 110. The motor module 150 includes a stator 153 provided to receive electric current based on external electric power and supported by the housing 110, and a rotor 155 provided rotatably corresponding to the stator 153, coupled to the partition wall member 117 in the middle region of the housing 110, and having the permanent magnet 161 and the motor rotation shaft 151. The permanent magnet 161 includes an exposed portion 161a at the outside thereof exposed toward the stator 153.
The stator 153 is the same as a general motor module 150, and thus detailed descriptions thereof will be avoided as necessary.
The rotor 155 includes a yoke holder 157 coupled to the motor rotation shaft 151, a yoke 159 having a first side coupled to the yoke holder 157 and a second side coupled to a separation preventing cab member 163, and the permanent magnet 161.
The yoke holder 157 is coupled to the motor rotation shaft 151, and on an upper side thereof includes a yoke coupling portion 157c recessed to couple with the yoke 159 and a permanent magnet holder 157a to be engaged with the permanent magnet 161, respectively. The yoke coupling portion 157c and the permanent magnet holder 157a may have various shapes corresponding to the shapes of the yoke 159 and the permanent magnet 161. Further, as necessary, adhesive or the like may be used to be coupled to the yoke coupling portion 157c and the permanent magnet holder 157a.
Meanwhile, the yoke holder 157 may be provided with ribs 157b formed between the permanent magnets 161 so that the plurality of permanent magnets 161 coupled in a circumferential direction can be separated and divided in the circumferential direction. As necessary, the ribs 157b may form an inclination portion inclined to the motor rotation shaft 151 so that the fluid can flow through a gap between the rotor 155 and the stator 153 as the rotor 155 rotates. Thus, the flow of the fluid is caused between the stator 153 and the rotor 155 to thereby effectively dissipating heat generated in the motor module 150.
Further, the separation preventing cab member 163 is provided to hold the upper sides of the yoke 159 and the permanent magnet 161 after the yoke 159 and the permanent magnet 161 are coupled to the yoke holder 157. In this case, the separation preventing cab member 163 includes a skirt 163a bent down from a top plate thereof so as to surround the upper end of the permanent magnet 161 or as necessary the upper end of the yoke 159. Thus, an inside of the permanent magnet 161 may be coupled to the yoke 159 by adhesive or the like, an outer lower end of the permanent magnet 161 may be supported by the permanent magnet holder 157a (refer to ‘K3’ in
A process of manufacturing the motor module 150 with this configuration according to an exemplary embodiment will be described with reference to
First, the yoke holder 157 is coupled to the motor rotation shaft 151. As described above, the yoke holder 157 is formed with the permanent magnet holder 157a, the rib 157b and the yoke coupling portion 157c.
Next, the yoke 159 is coupled onto the upper side of the yoke coupling portion 157c recessed in the yoke holder 157.
After coupling the yoke 159, adhesive or the like is applied to the region for coupling with the yoke 159 and then the plurality of permanent magnets 161 is coupled to the permanent magnet holder 157a. The plurality of permanent magnets 161 may be arranged to be spaced apart from each other by the ribs 157b in the circumferential direction.
Next, the separation preventing cab member 163 is coupled to the upper sides of the permanent magnet 161 and the yoke 159 so that the permanent magnet 161 can be firmly supported in the yoke holder 157 by the end of the permanent magnet 161 surrounded with the skirt 163a without being separated in the circumferential direction or in an upward direction.
Thus, both ends of the permanent magnet 161 are not separated in a radial direction or in a lengthwise direction by the permanent magnet holder 157a and the skirt 163a, respectively, and at the same time the middle region of the permanent magnet may form the exposed portion 161a exposed in the circumferential direction.
Here, data comparison between the related art and the present embodiment is as follows.
The following [Table 1] shows experimental data under the condition that the permanent magnet of the rotor is fully surrounded according to the related art and experimental data under the condition that the permanent magnet of the rotor is exposed according to an exemplary embodiment.
As shown in [Table 1], under the same condition that a constant torque of 0.600 N-m is generated, the related art shows the efficiency of 63.7% but the present embodiment shows 74.2%, which shows that the efficiency of the present embodiment is increased by about 16%. Likewise, under the same condition that a torque is 1.2 N-m, the related art shows the efficiency of 35.9% but the present embodiment shows 74.7%, which shows that the efficiency of the present embodiment is significantly increased as compared with that of the related art.
Thus, on the contrary to the related art, the permanent magnet 161 provides the maximum exposed portion 161a as possible, and thus magnetic force generated by the permanent magnet 161 or the like is not interfered to thereby enhance magnetic properties and improve the efficiency of the motor. Also, the permanent magnet is not fully surrounded, so that the structure for supporting the permanent magnet can become simpler and more convenient, thereby lowering molding costs or the like. In addition, the simple structure may cause the number of parts to be reduced, thereby simplifying manufacture, assembly, etc. and raising economical efficiency.
According to an exemplary embodiment, there is provided a hydraulic power steering pump having a wet type motor with an open type magnet, in which a coupling structure of a permanent magnet arranged in a rotor is improved to enhance magnetic properties of the permanent magnet to thereby increase efficiency of a motor, a structure of coupling the permanent magnet is simplified to lower costs of manufacturing molding or the like and thus raise economical efficiency, and the simple structure causes processes of to be simplified.
Although a few exemplary embodiments have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2012-0009019 | Jan 2012 | KR | national |
